FINAL

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CHAPTER 1
1. INTRODUCTIONTO WSN:
1.1. WIRELESS SENSOR NETWORK(WSN):
A wireless sensor network (WSN) is a wireless network consisting of
Spatially distributed autonomous devices using sensors to monitor physical or
environmental conditions. A WSN system incorporates a gateway that provides
wireless connectivity back to the wired world and distributed nodes (see Figure
1.1). The wireless protocol you select depends on your application
requirements. Some of the available standards include 2.4 GHz radios based on
either IEEE 802.15.4 or IEEE 802.11 (Wi-Fi) standards or proprietary radios,
which are usually 900 MHz
Fig 1.1 WSN Architecture
1.2. COMPONENTS OF WSN:
Sensor nodes communicate with each other in order to forward their
sensed information to a central processing unit or conduct some local
coordination such as data fusion. The usual hardware components of a sensor

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node include a radio transceiver, an embedded processor, internal and external
memories, a power source and one or more sensors.
Fig 1.2. WSN COMPONENTS.
1.2.1. EmbeddedProcessor:
In a sensor node, the functionality of an embedded processor is to
schedule tasks, process data and control the functionality of other hardware
components. The types of embedded processors that can be used in a sensor
node include Microcontroller, Digital Signal Processor (DSP), Field
Programmable Gate Array (FPGA) and Application Specific Integrated Circuit
(ASIC). Among all these alternatives, the Microcontroller has been the most
used embedded processor for sensor nodes because of its flexibility to connect
to other devices and its cheap price. For example, the newest CC2531
development board provided by Clipcon (acquired by Texas Instruments) uses
8051 microcontroller, and the Mica2 Mote platform provided by Crossbow uses
ATMega128L microcontroller.

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1.2.2 .Transceiver:
A transceiver is responsible for the wireless communication of a sensor
node. The various choices of wireless transmission media include Radio
Frequency (RF), Laser and Infrared. RF based communication fits to most of
WSN applications. The operational states of a transceiver are Transmit,
Receive, Idle and Sleep. Mica2 Mote uses two kinds of RF radios: RFM
TR1000 and Chip con CC1000. The outdoor transmission range of Mica2 Mote
is about 150 meters.
1.2.3 Memory:
Memories in a sensor node include in-chip flash memory and RAM of a
microcontroller and external flash memory. For example, the ATMega128L
microcontroller running on Mica2 Mote has 128-Kbyte flash program memory
and 4-Kbyte static RAM. Further, a 4-Mbit Atmel AT45DB041B serial flash
chip can provide external memories for Mica and Mica2Motes (Hill, 2003).
1.2.4 .Power Source:
In a sensor node, power is consumed by sensing, communication and
data processing. More energy is required for data communication than for
sensing and data processing. Power can be stored in batteries or capacitors.
Batteries are the main source of power supply for sensor nodes. For example,
Mica2 Mote runs on 2 AA batteries. Due to the limited capacity of batteries,
Minimizing the energy consumption is always a key concern during WSN
operations. To remove the energy constraint, some preliminary research
working on energy-harvesting techniques for WSNs has also been conducted.
Energy-harvesting techniques convert ambient energy (e.g. solar, wind) to
electrical energy and the aim is to revolutionize the power supply on sensor
nodes. A survey about the energy-harvesting sensor nodes is provided by
(Sudevalayam & Kulkarni, 2008).

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1.2.5 .Sensors:
A sensor is a hardware device that produces a measurable response signal
to a change in a physical condition such as temperature, pressure and humidity.
The continual analog signal sensed by the sensors is digitized by an analog-to-
digital converter and sent to the embedded processor for further processing.
Because a sensor node is a micro-electronic device powered by a limited power
source, the attached sensors should also be small in size and consume extremely
low energy. A sensor node can have one or several types of sensors integrated
in or connected to the node.
1.2.6. Battery:
The battery is an important component in sensor node. It supplies power
to all component of sensor node. Therefore, sensor nodes lifetime totally
depends on battery and network’s lifetime depends on lifetime of sensor nodes.
The amount of power drained from a battery should be checked. Since Sensor
nodes are usually small, light and cheap and the size of the battery is limited.
(Advancement in Battery technologies much slower than semiconductor
technologies. For example, the energy densities of Li-ion batteries only
increased 50% from 1994 to 1999. While in the same period of time, the
number of transistors of Intel processors doubles every 24 months.). Sensor
nodes are deployed in unattended environment where battery replacement is not
possible in network which consists of thousands of nodes. Hence, energy
consumption is vital factor to prolong sensor nodes lifetime.
1.3. CHARACTERISTICS OF WSN:
The main characteristics of a WSN include
 Power consumption constrains for nodes using batteries or energy
harvesting
 Ability to cope with node failures

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 Mobility of nodes
 Dynamic network topology
 Communication failures
 Heterogeneity of nodes
 Scalability to large scale of deployment
 Ability to withstand harsh environmental conditions
 Ease of use
 Unattended operation
 Power consumption
1.4. APPLICATIONS
Wireless sensor network has lots of applications like security, monitoring,
biomedical research, tracking etc. Basically these applications are used
emergency services. The applications of the sensor network are categorized into
various classes such as Environmental data collection, Military applications,
Security monitoring, sensor node tracking, health application, home application,
and hybrid networks.
1.4.1. Environmental Data Collection:
In environmental data collection application, are used collect various
sensor data in a period of time. If a data to be meaningful so collecting sensor
data at regular interval and the nodes would remain at known locations. In the
environmental data collection application, a large number of nodes continuously
sensing and transmitting data back to a set of base stations that store the data
using traditional methods. In typical usage scenario, the nodes will be evenly
distributed over an outdoor environment. In environmental monitoring
applications, it is not essential that the nodes develop the optimal routing
strategies on their own. Instead, it may be possible to calculate the optimal
routing topology outside of the network and then communicate the necessary

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sensor data to the nodes as required. This is possible because the physical
topology of the network is relatively constant. While the time variant nature of
RF communication may cause connectivity between two nodes to be
intermittent, the overall topology of the network will be relatively stable.
1.4.2. Military Applications:
Most of the elemental knowledge of sensor networks is basic on the
defense application at the beginning, especially two important programs the
Distributed Sensor Networks (DSN) and the Sensor Information Technology
form the Defense Advanced Research Project Agency (DARPA), sensor
networks are applied very successfully in the military sensing. Now, wireless
sensor networks can be an integral part of military command, control,
communications, computing, intelligence, surveillance, reconnaissance and
targeting systems. In the battlefield context, rapid deployment, self-
organization, fault tolerance security of the network should be required. The
sensor devices or nodes should provide following services: like Monitoring
friendly forces, equipment and ammunition, Battlefield surveillance,
Reconnaissance of opposing forces, Targeting, Battle damage assessment
Nuclear, biological and chemical attack detection reconnaissance.
1.4.3. Security Monitoring:
Security monitoring networks are collected of nodes that are placed at
fixed locations throughout an environment that continually monitor one or more
sensors to detect an anomaly. A key difference between security monitoring and
environmental monitoring is that security networks are not actually collecting
any data. This has a significant impact on the optimal network architecture.
Each node has to frequently check the status of its sensors but it only has to
transmit a data report when there is a security violation. The immediate and
reliable communication of alarm messages is the primary system requirement.

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These are “report by exception” networks. It is confirmed that each node is still
present and functioning. If a node were to be disabled or fail, it would represent
a security violation that should be reported. For security monitoring
applications, the network must be configured so that nodes are responsible for
confirming the status of each other. One approach is to have each node be
assigned to peer that will report if a node is not functioning. The optimal
topology of a security monitoring network will look quite different from that of
a data collection network. In a collection tree, each node must transmit the data
of all of its decedents. The accepted norm for security systems today is that each
sensor should be checked approximately once per hour. Combined with the
ability to evenly distribute the load of checking nodes, the energy cost of
performing this check becomes minimal. A majority of the energy consumption
in a security network is spent on meeting the strict latency requirements
associated with the signaling the alarm when a security violation occurs. In
security networks, a vast majority of the energy will be spend on confirming the
functionality of neighboring nodes and in being prepared to instantly forward
alarm announcements. Actual data transmission will consume a small fraction
of the network energy.
1.4.4. Node tracking scenarios:
In which wireless sensor network is the tracking of a tagged object
through a area of space monitored by a sensor network. There are many
conditions where one would like to track the location of important assets or
personnel. Current inventory control systems attempt to track objects by
recording the last checkpoint that an object passed through. However, with
these systems it is not possible to determine the current location of an object.
For example, UPS tracks every shipment by scanning it with a barcode
whenever it passes through routing centers. The system breaks down when
objects do not flow from checkpoint to checkpoint. In typical work

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environments it is impractical to expect objects to be continuously passed
through checkpoints. With wireless sensor networks, objects can be tracked by
simply tagging them with a small sensor node. The sensor node will be tracked
as it moves through a field of sensor nodes that are deployed in the environment
at known locations. Instead of sensing environmental data, these nodes will be
deployed to sense the RF messages of the nodes attached to various objects. The
nodes can be used as active tags that announce the presence of a device. A
database can be used to record the location of tracked objects relative to the set
of nodes at known locations. With this system, it becomes possible to ask where
an object is currently, not simply where it was last scanned. Unlike sensing or
security networks, node tracking applications will continually have topology
changes as nodes move through the network. While the connectivity between
the nodes at fixed locations will remain relatively stable, the connectivity to
mobile nodes will be continually changing.
1.4.5. Health Applications
Sensor networks are also widely used in health care area. In some modern
hospital sensor networks are constructed to monitor patient physiological data,
to control the drug administration track and monitor patients and doctors and
inside a hospital. In spring 2004 some hospital in Taiwan even use RFID basic
of above named applications to get the situation at first hand. Long-term nursing
home this application is focus on nursing of old people. In the town farm
cameras, pressure sensors, orientation sensors and sensors for detection of
muscle activity construct a complex network. They support fall detection,
unconsciousness detection, vital sign monitoring and dietary/exercise
monitoring. These applications reduce personnel cost and rapid the reaction of
emergence situation.

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1.4.6. Home Application:
Along with developing commercial application of sensor network it is no
so hard to image that Home application will step into our normal life in the
future. Many concepts are already designed by researcher and architects, like
“Smart Environment: Some are even realized. Let’s see the concept “the
intelligent home”: After one day hard work you come back home. At the front
door the sensor detects you are opening the door, then it will tell the electric
kettle to boil some water and the air condition to be turned on. You sit in the
sofa lazily. The light on the table and is automatically on because the pressure
sensor under the cushion has detected your weight. The TV is also on. One
sensor has monitored that you are sitting in front of it. “I’m simply roasting. The
summer time in Asia is really painful.” You think and turn down the
temperature of the air condition. At the sometime five sensors in every corner in
the room are measuring the temperature. Originally there is also sensor in the air
condition. But it can only get the temperature at the edge of the machine not the
real temperature in the room. So the sensors in the room will be detecting the
environment. The air condition will turn to sleep mode until all the sensors get
the right temperature. The light on the corridor, in the washing groom and
balcony are all installed with sensor and they can be turned on or turn out
automatically. Even the widows are also attached with vibratory sensors
connected to police to against thief. How nice! You become nurse and
bodyguard at the same time.
1.5. ROUTING CHALLENGES AND ISSEUES IN WSNs:
Despite the innumerable applications of WSNs, these networks have
several restrictions, e.g., limited energy supply, limited computing power, and
limited bandwidth of the wireless links connecting sensor nodes. One of the
main design goals of WSNs is to carry out data communication while trying to

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prolong the lifetime of the network and prevent connectivity degradation by
employing aggressive energy management techniques. The design of routing
protocols in WSNs is influenced by many challenging factors. These factors
must be overcome before efficient communication can be achieved in WSNs. In
the following, we summarize some of the routing challenges and design issues
that aspect routing process in WSNs.
1.5.1. Node deployment:
Node deployment in WSNs is application dependent and affects the
performance of the routing protocol. The deployment can be either deterministic
or randomized. In deterministic deployment, the sensors are manually placed
and data is routed through pre-determined paths. However, in random node
deployment, the sensor nodes are scattered randomly creating an infrastructure
in an ad hoc manner. If the resultant distribution of nodes is not uniform,
optimal clustering becomes necessary to allow connectivity and enable energy
efficient network operation. Inter-sensor communication is normally within
short transmission ranges due to energy and bandwidth limitations. Therefore, it
is most likely that a route will consist of multiple wireless hops.
1.5.2. Energy consumption without losing accuracy:
Sensor nodes can use up their limited supply of energy performing
computations and transmitting information in a wireless environment. As such,
energy-conserving forms of communication and computation are essential.
Sensor node lifetime shows a strong dependence on the battery lifetime. In a
multihop WSN, each node plays a dual role as data sender and data router. The
malfunctioning of some sensor nodes due to power failure can cause significant
topological changes and might require rerouting of packets and reorganization
of the network.

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1.5.3. Data Reporting Model:
Data sensing and reporting in WSNs is dependent on the application
and the time criticality of the data reporting. Data reporting can be categorized
as either time-driven (continuous), event-driven, query-driven, and hybrid. The
time-driven delivery model is suitable for applications that require periodic data
monitoring. As such, sensor nodes will periodically switch on their sensors and
transmitters, sense the environment and transmit the data of interest at constant
periodic time intervals. In event-driven and query-driven models, sensor nodes
react immediately to sudden and drastic changes in the value of a sensed
attribute due to the occurrence of a certain event or a query is generated by the
BS. As such, these are well suited for time critical applications. A combination
of the previous models is also possible. The routing protocol is highly
influenced by the data reporting model with regard to energy consumption and
route stability.
1.5.4. Node/Link Heterogeneity:
In many studies, all sensor nodes were assumed to be homogeneous,
i.e., having equal capacity in terms of computation, communication, and power.
However, depending on the application a sensor node can have role or
capability. The existence of heterogeneous set of sensors raises many technical
issues related to data routing. For example, some applications might require a
diverse mixture of sensors for monitoring temperature, pressure and humidity of
the surrounding environment, detecting motion via acoustic signatures, and
capturing the image or video tracking of moving objects. These special sensors
can be either deployed independently or the different functionalities can be
included in the same sensor nodes. Even data reading and reporting can be
generated from these sensors at different rates, subject to diverse quality of
service constraints, and can follow multiple data reporting models. For example,
hierarchical protocols designate a cluster heads node different from the normal
sensors. These cluster heads can be chosen from the deployed sensors or can be

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more powerful than other sensor nodes in terms of energy, bandwidth, and
memory. Hence, the burden of transmission to the BS is handled by the set of
cluster heads.
1.5.5. Fault Tolerance:
Some sensor nodes may fail or be blocked due to lack of power, physical
damage, or environmental interference. The failure of sensor nodes should not
affect the overall task of the sensor network. If many nodes fail, MAC and
routing protocols must accommodate formation of new links
and routes to the data collection base stations. This may require actively
adjusting transmit powers and signaling rates on the existing links to reduce
energy consumption, or rerouting packets through regions of the network where
more energy is available. Therefore, multiple levels of redundancy may be
needed in a fault-tolerant sensor network.
1.5.6. Scalability:
The number of sensor nodes deployed in the sensing area may be in the
order of hundreds or thousands, or more. Any routing scheme must be able to
work with this huge number of sensor nodes. In addition, sensor network
routing protocols should be scalable enough to respond to events in the
environment. Until an event occurs, most of the sensors can remain in the sleep
state, with data from the few remaining sensors providing a coarse quality.
1.5.7. Network Dynamics:
Most of the network architectures assume that sensor nodes are stationary.
However, mobility of both BS’s and sensor nodes is sometimes necessary in
many applications. Routing messages from or to moving nodes is more
challenging since route stability becomes an important
issue, in addition to energy, bandwidth etc. Moreover, the sensed phenomenon
can be either dynamic or static depending on the application, e.g., it is dynamic
in a target detection/tracking application, while it is static in forest monitoring

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for early fire prevention. Monitoring static events allows the network to work in
a reactive mode, simply generating traffic when reporting. Dynamic events in
most applications require periodic reporting and consequently generate
significant traffic to be routed to the BS.
1.5.8. Transmission Media:
In a multi-hop sensor network, communicating nodes are linked by a
wireless medium. The traditional problems associated with a wireless channel
(e.g., fading, high error rate) may also affect the operation of the sensor
network. In general, the required bandwidth of sensor data will be low, on the
order of 1-100 kb/s. Related to the transmission media is the design of medium
access control (MAC). One approach of MAC design for sensor networks is to
use TDMA based protocols that conserve more energy compared to contention
based protocols like CSMA (e.g., IEEE 802.11). Bluetooth technology can also
be used.
1.5.9. Connectivity:
High node density in sensor networks precludes them from being
completely isolated from each other. Therefore, sensor nodes are expected to be
highly connected. This, however, may not prevent the network topology from
being variable and the network size from being shrinking due to sensor node
failures. In addition, connectivity depends on the, possibly random, distribution
of nodes.
1.5.10. Coverage:
In WSNs, each sensor node obtains a certain view of the environment. A
given sensor's view of the environment is limited both in range and in accuracy;
it can only cover a limited physical area of the environment. Hence, area
coverage is also an important design parameter in WSNs.
1.5.11. Data Aggregation:
Since sensor nodes may generate significant redundant data, similar
packets from multiple nodes can be aggregated so that the number of

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transmissions is reduced. Data aggregation is the combination of data from
different sources according to a certain aggregation function, e.g., duplicate
suppression, minima, maxima and average. This technique has been used to
achieve energy efficiency and data transfer optimization in a number of routing
protocols. Signal processing methods can also be used for data aggregation. In
this case, it is referred to as data fusion where a node is capable of producing a
more accurate output signal by using some techniques such as beam forming to
combine the incoming signals and reducing the noise in these signals.
1.5.12. Quality of Service:
In some applications, data should be delivered within a certain period of
time from the moment it is sensed; otherwise the data will be useless. Therefore
bounded latency for data delivery is another condition for time-constrained
applications. However, in many applications, conservation of energy, which is
directly related to network lifetime, is considered relatively more important than
the quality of data sent. As the energy gets depleted, the network may be
required to reduce the quality of the results in order to reduce the energy
dissipation in the nodes and hence lengthen the total network lifetime. Hence,
energy-aware routing protocols are required to capture this requirement.

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CHAPTER 2
2. ANTENNA INTRODUCTION:
2.1. ANTENNA:
An antenna is a specialized transducer that converts radio-frequency (RF)
fields into alternating current (AC) or vice-versa to radiated electromagnetic
energy in free space. Typically an antenna consists of an arrangement of
metallic conductors, electrically connected (often through a transmission line) to
the receiver or transmitter. There are two basic types: the receiving antenna,
which intercepts RF energy and delivers AC to electronic equipment, and the
transmitting antenna, which is fed with AC from electronic equipment and
generates an RF field.
Antennas may also be viewed as an impedance transformer,
coupling between an input or line impedance, and the impedance of free space.
Without an efficient antenna, electromagnetic energy would not be radiated and
wireless communication over long distance would be impossible.
Fig 2.1 Antenna principle
The source information is normally modulated and amplified in the
transmitter and then passed on to the transmit antenna via a transmission line,
which has a typical characteristic impedance of 50 ohms. The antenna radiates

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the information in the form of an electromagnetic wave in an efficient and
desired manner to the destination, where the information is picked up by the
receive antenna and passed on to the receiver via another transmission line. The
signal is demodulated and the original message is then recovered at the receiver.
2.2. FUNDAMENTAL PARAMETERS OF ANTENNAS:
2.2.1 Input Impedance:
The input impedance of a transmission line is defined as the ratio of
voltage to current at the input port and is the impedance looking towards the
load
2.2.2. Radiation Resistance:
Radiation resistance is that part of an antenna's feed point resistance that
is caused by the radiation of electromagnetic waves from the antenna. The
radiation resistance is determined by the geometry of the antenna, not by the
materials of which it is made. It can be viewed as the equivalent resistance to a
resistor in the same circuit.
Where is the electric current flowing into the feeds of the antenna and is the
power in the resulting electromagnetic field.
2.2.3. Radiation pattern:
An antenna radiation pattern or antenna pattern is defined as a
mathematical function or a graphical representation of the radiation properties
of the antenna as a function of space coordinates.

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Fig 2.2. TYPE OF RADIATION PATTERN.
All three patterns yield the same angular separation between the two half
power points, 38.64±, on their respective patterns, referred to as HPBW.
Radiation Pattern Lobes
A radiation lobe is a portion of the radiation pattern bounded by regions of
Relatively weak radiation intensity.
• Main lobe • Minor lobes
• Side lobes • Back lobes

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Fig 2.3 Radiation pattern lobes
Isotropic, Directional, and Omnidirectional Patterns:
Isotropic Radiator: A hypothetical lossless antenna having equal radiation in
all directions.
Omnidirectional Radiator: An antenna having an essentially nondirectional
pattern in a given plane (e.g., in azimuth) and a directional pattern in any
orthogonal plane.
Directional Radiator: An antenna having the property of radiating or
receiving more effectively in some directions than in others. Usually the
maximum directivity is significantly greater than that of a half-wave dipole.
2.2.4. Beamwidth:
• The beamwidth of an antenna is a very important figure of merit and often
is used as a trade-off between it and the side lobe level; that is, as the
beamwidth decreases, the side lobe increases and vice versa.
• The beamwidth of the antenna is also used to describe the resolution
capabilities of the antenna to distinguish between two adjacent radiating
sources or radar targets.
Half-Power Beam Width (HPBW): In a plane containing the direction
of the maximum of a beam, the angle between the two directions in

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which the radiation intensity is one-half value of the beam.
First-Null Beam width (FNBW): Angular separation between the
first nulls of the pattern.
Fig 2.4. Beamwidth
2.2.5. Gain and directivity:
The gain of the antenna is the quantity which describes the performance
of the antenna or the capability to concentrate energy through a direction to give
a better picture of the radiation performance. This is expressed in dB, in a
simple way we can say that this refers to the direction of the maximum
radiation.
The expression for the maximum gain of an antenna is as follows:
G = η x D
η – The efficiency of the antenna
D – Directivity
In order to receive or transmit the power it can be chosen to maximize the
radiation pattern of the response of the antenna in a particular direction.

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Fig 2.5 Directivity of an antenna
The directivity of the antenna depends on the shape of the radiation pattern. The
measurement is done taking a reference of isotropic point source from the
response. The quantitative measure of this response is known as the directive
gain for the antenna on a given direction.
rectional antenna.
2.5.6. Polarization:
The polarization of the electric field vector of the radiated wave or from source
Vs time the observation of the orientation of the electric fields does also refer to
the polarization. It is defined as” the property of an electromagnetic wave
describing the time varying direction and relative magnitude of the electric filed
vector”.

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The direction or position of the electric field w.r.t the ground gives the wave
polarization. The common types of the polarization are circular and linear the
former includes horizontal and vertical and the latter includes right hand
polarization and left hand polarization.
Fig 2.6 A linearly polarized wave
2.5.7. Reflection Coefficient |Г| and Character Impedance (Z0) :
There is a reflection that occurs in the transmission line when we take the higher
frequencies in to consideration. There is a resistance that is associated with each
transmission line which comes with the construction of the transmission line.
This is called as character impedance (Z0). The standard value of this
impedance is 50ohm. Always the every transmission line is being terminated
with an arbitrary load ZL and this is not equivalent to the impedance i.e. Z0.
Here occurs the reflected wave.
The degree of impedance mismatch is represented by the reflection coefficient
[1] at that load and is given by:
We can observe here that the reflection coefficient for the shorted load ZL=0,
there is a match in the load ZL=Z0 and an open load ZL = ∞ are -1, 0, +1. [22]

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Hence we can say that the reflection coefficient ranges from 0 to +1.
2.5.8. Voltage Standing Wave Ratio :
There should be a maximum power transfer between the transmitter and the
antenna for the antenna to perform efficiently. This happens only when the
impedance Zin is matched to the transmitter impedance, Zs.
In the process of achieving this particular configuration for an antenna to
perform efficiently there is always a reflection of the power which leads to the
standing waves, which is characterized by the Voltage Standing Wave Ratio
(VSWR).
This is given by :
As the reflection coefficient ranges from 0 to 1, the VSWR ranges from 1 to ∞.
2.5.9. Bandwidth:
Bandwidth can be said as the frequencies on both the sides of the centre
frequency in which the characteristics of antenna such as the input impedance,
polarization, beam width, radiation pattern etc are almost close to that of this
value. As the definition goes “the range of suitable frequencies within which the
performance of the antenna, w.r.t some characteristic, conforms to a specific
standard”.
The bandwidth is the ratio of the upper and lower frequencies of an operation.
According to [22] the bandwidth can be obtained as:
BW broadband = fL/ fH
BW narrowband (%) = 100*{(fH-fL)/fC}

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When the ratio fL/fH= 2 the antenna is said to be broadband. We can judge the
antenna’s performance by operating the antenna at a high frequency by
observing VSWR, when VSWR≤2.
2.5.10. Input Impedance:
This is the ratio of the voltage to current at the pair of terminals or the ratio of
the appropriate components of the electric fields to the magnetic fields at a
point. Or in other words we can say it is the impedance presented by the antenna
at the input terminal.
Zin = (Rin + jXin)
Rin – the real part, representing the power dissipated though heat or through
radiation losses.
Xin = imaginary part, representing the reactance of the antenna & the power
stored in the near field of the antenna.
2.5.11. Power Gain:
The power gain of an antenna is a ratio of the power input to the antenna
to the power output from the antenna. This gain is most often referred to with
the units of dBi.
GP = Pload/Pinput
Where Pload is the maximum power delivered to the load
Pin is the average power entering the network
2.5.12. Radar Cross Section:
Radar cross-section (RCS)σis defined as the ability of a target to reflect
the energy back to the radar.
It is the ratio of the backscattered power to the incident power density;
that is

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2.3. ANTENNA TYPES:
2.3.1. WIRE ANTENNA:
2.3.1.1. Short Dipole Antenna:
A dipole is antenna composed of a single radiating element split into two
sections, not necessarily of equal length. . Hertz used them for his famous
experiment. As shown in Figure 5.1, a dipole can be considered a structure
evolved from an open-end, two-wire transmission line.
Fig 2.7 Short dipole antenna
2.3.1.2. Monopole Antenna
The monopole antenna is half of the dipole antenna, which is a dipole
with length 2l in free space. The current distribution along the pole is the same
as the dipole discussed earlier, thus the radiation pattern is the same above the
ground plane.
Fig 2.8 Monopole Antenna
2.3.1.3. Small Loop Antenna:
The single-turn loop antenna is a metallic conductor bent into the shape
of a closed curve, such as a circle or a square, with a gap in the conductor to
form the terminals. A multiturn loop or coil is a series connection of overlaying

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turns. The loop is one of the primary antenna structures; its use as a receiving
antenna dates back to the early experiments of Hertz on the propagation of
electromagnetic waves
Fig 2.9 Small loop antenna
2.3.1.4. Folded Dipole Antenna:
Fig 2.10 Folded dipole antenna
A variation of the dipole antenna is the folded dipole as shown. Its
radiation pattern is very similar to the simple dipole, but its impedance is higher
and it has a wider bandwidth.
2.3.2. TRAVELLING WAVE ANTENNAS:
2.3.2.1. Helical antennas
A helical antenna consists of a conductor wound into a helical shape. It is
a circularly/elliptically polarized antenna. A helix wound like a righthand

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(clockwise) screw radiates or receives right-hand circularly polarized waves,
whereas a helix wound like a left-hand (anti-clockwise) screw radiates or
receives left-hand circularly polarized waves.
Fig 2.11 Helical antenna
2.3.2.2. Yagi-uda antennas
Another antenna design that uses passive elements is the Yagi antenna. This
antenna, illustrated in figure 15, is inexpensive and effective. It can be
constructed with one or more (usually one or two) reflector elements and one or
more (usually two or more) director elements.
Fig 2.12 Yagi-uda antenna with three elements
A typical pattern for a three element (one reflector, one active element,
and one director) Yagi antenna is shown above. Generally, the more elements a
Yagi has, the higher the gain, and the narrower the beam width.

27
2.3.3. APERTURE ANTENNAS:
2.3.3.1. Slot antenna
The slotted antenna exhibits radiation characteristics that are very similar
to those of the dipole. The elevation and azimuth patterns are similar to those of
the dipole, but its physical construction consists only of a narrow slot cut into
ground plane.
As with micro strip antennas mentioned below, slotted antennas provide
little antenna gain, and do not exhibit high directionality, as evidenced by their
radiation plots and their similarity to the dipoles.
Fig 2.13 Slot Antenna
2.3.3.2. Horn Antennas
The only practical way to increase the directivity of a waveguide is to
flare out its ends into a horn. Fig. 18.2.1 shows three types of horns: The H-
plane sect-oral horn in which the long side of the waveguide (the a-side) is
flared, the E-plane sect-oral horn in which the short side is flared, and the
pyramidal horn in which both sides are flared.
Fig 2.14 Horn Antenna

28
H-plane, E-plane and pyramidal horns. The pyramidal horn is the most
widely used antenna for feeding large microwave dish antennas and for
calibrating them. The sect-oral horns may be considered as special limits of the
pyramidal horn.
2.3.4. REFLECTOR ANTENNAS:
2.3.4.1. Corner Reflector Antenna
An antenna comprised of one or more dipole elements in front of a corner
reflector, called the corner-reflector antenna, is illustrated in figure. A
photograph of a typical corner reflector is also shown.
Fig 2.15 Reflector Antenna
This antenna has moderately high gain, but its most important pattern
feature is that the forward (main beam) gain is much higher than the gain in the
opposite direction. This is called the front-to-back ratio.
2.3.4.2. Parabolic Reflector (Dish Antenna)
A parabola is a two dimensional plane curve. A practical reflector is a
three dimensional curved surface. Therefore a practical reflector is formed by
rotating a parabola about its axis. The surface so generated is known as
“paraboloid” which is often called as “microwave dish” or “parabolic reflector”.

29
The paraboloid reflector antenna consists of a primary antenna such as a dipole
or horn situated at the focal point of a parabolic reflector. The important
practical implication of this property is that reflector can focus parallel rays on
to the focal point or conversely it can produce a parallel beam from radiations
originating from the focal point.
Fig 2.16 Parabolic Reflector Antenna
2.3.5. PLANAR ANTENNAS:
2.3.5.1. Rectangular Micro-strip (patch) Antenna.
A Micro-strip patch antenna consists of a radiating patch on one side of a
dielectric substrate which has a ground plane on the other side.
Fig 2.17 Microstrip patch Antenna

30
Microstrip or patch antennas are becoming increasingly useful because
they can be printed directly onto a circuit board. Microstrip antennas are
becoming very widespread within the mobile phone market. Patch antennas are
low cost, have a low profile and are easily fabricated.
Different Shapes of Micro-strip Patch Elements:
Fig 2.18 Microstrip patch Elements
2.3.5.2. Coplanar Waveguide antenna:
The CPW is another popular planar transmission line. Just like a strip
line, it may be considered a structure evolved from a coaxial cable. This
structure can also be viewed as a coplanar strip line. The central conductor is
separated from a pair of ground planes. They all sit on a substrate with a
dielectric permittivity of ε.
2.4. FEEDING TECHNIC:
2.4.1. Microstrip (Offset Microstrip) Line Feed:
In this type of feed technique, a conducting strip is connected directly to the
edge of the microstrip patch as shown in figure 2.16. The conducting strip is
smaller in width as compared to the patch. This kind of feed arrangement has
the advantage that the feed can be etched on the same substrate to provide a
planar structure.

31
Fig 2.19 Microstrip Line Feed
An inset cut can be incorporated into the patch in order to obtain good
impedance matching without the need for any additional matching element.
This is achieved by properly controlling the inset position. Hence this is an easy
feeding technique, since it provides ease of fabrication and simplicity in
modeling as well as impedance matching. However as the thickness of the
dielectric substrate increases, surface waves and spurious feed radiation also
increases, which hampers the bandwidth of the antenna. This type of feeding
technique results in undesirable cross polarization effects.
2.4.2. Coaxial Feed:
The Coaxial feed or probe feed is one of the most common techniques used for
feeding microstrip patch antennas. As seen from figure 2.17, the inner
conductorof the coaxial connector extends through the dielectric and is soldered
to the radiating patch, while the outer conductor is connected to the ground
plane.

32
Fig 2.20 Coaxial Feed
The main advantage of this type of feeding scheme is that the feed can be placed
at any desired position inside the patch in order to obtain impedance matching.
This feed method is easy to fabricate and has low spurious radiation effects.
However, its major disadvantage is that it provides narrow bandwidth and is
difficult to model since a hole has to be drilled into the substrate. Also, for
thicker substrates, the increased probe length makes the input impedance more
inductive, leading to matching problems.
By using a thick dielectric substrate to improve the bandwidth, the microstrip
line feed and the coaxial feed suffer from numerous disadvantages such as
spurious feed radiation and matching problem. The non-contacting feed
techniques which have been discussed below, solve these problems.
2.4.3. Aperture Coupled Feed:
In aperture coupling as shown in figure 2.18 the radiating microstrip patch
element is etched on the top of the antenna substrate, and the microstrip feed
line is etched on the bottom of the feed substrate in order to obtain aperture
coupling. The thickness and dielectric constants of these two substrates may

33
thus be chosen independently to optimize the distinct electrical functions of
radiation and circuitry. The coupling aperture is usually centered under the
patch, leading to lower cross-polarization due to symmetry of the configuration.
The amount of coupling from the feed line to the patch is determined by the
shape, size and location of the aperture. Since the ground plane separates the
patch and the feed line, spurious radiation is minimized.
Fig 2.21 Aperture Coupled Feed
Generally, a high dielectric material is used for bottom substrate and a thick,
low dielectric constant material is used for the top substrate to optimize
radiation from the patch. This type of feeding technique can give very high
bandwidth of about 21%. Also the effect of spurious radiation is very less as
compared to other feed techniques. The major disadvantage of this feed
technique is that it is difficult to fabricate due to multiple layers, which also
increases the antenna thickness.
2.4.4. Proximity Coupled Feed:
This type of feed technique is also called as the electromagnetic coupling
scheme. As shown in figure 2.19, two dielectric substrates are used such that the
feed line is between the two substrates and the radiating patch is on top of the
upper substrate. The main advantage of this feed technique is that it eliminates

34
spurious feed radiation and provides very high bandwidth of about 13%, due to
increase in the electrical thickness of the microstrip patch antenna. This scheme
also provides choices between two different dielectric media, one for the patch
and one for the feed line to optimize the individual performances.
Fig 2.22 Proximity Coupled Feed
The major disadvantage of this feed scheme is that it is difficult to
fabricate because of the two dielectric layers that need proper alignment. Also,
there is an increase in the overall thickness of the antenna.
2.4.5. COPLANAR WAVEGUDIE FEEDING:
The CPW is the feeding which side-plane conductor is ground and center
strip carries the signal. Recently CPW-fed printed antennas have received
considerable attention owing to their attractive merits, such as ultra-wide
frequency band, good radiation properties and easy integration with system
circuits.

35
Feed line is one of the important components of antenna structure given
below in Figure. Coplanar waveguide structure is becoming popular feed line
for an antenna. The coplanar waveguide was proposed by C.P. Wen in 1969. A
coplanar waveguide structure consists of a median metallic strip of deposited on
the surface of a dielectric substrate slab with two narrow slits ground electrodes
running adjacent and parallel to the strip on the same surface. This transmission
line is uni-planar in construction, which implies that all of the conductors are on
the same side of the substrate. CPW Feed Structure Etching the slot and the
feed line on the same side of the substrate eliminates the alignment problem
needed in other wideband feeding techniques such as aperture coupled and
proximity feed.
Fig.2.23 CPW Feed

36
CHAPTER 3
3. LITERATURE SURVEY:
3.1 A COMPACT CPW-FEDUWB ANTENNAWITH GSM, GPS,
BLUETOOTHAND DUAL NOTCHBANDS APPLICATIONS:
Luo, Yonglun, et al. "A COMPACT CPW-FED UWB ANTENNA WITH GSM, GPS, BLUETOOTH AND
DUAL NOTCH BANDS APPLICATIONS." Progress In Electromagnetics Research C 35 (2013).
Abstract-A novel compact ultrawideband (UWB) CPW-fed antenna with triple
lower pass bands and dual notched bands for wireless applications is presented.
The low-profile antenna comprises of an approximate hexagonal-shaped
radiator for covering the UWB band (3:1 ~ 10:8 GHz). Triple lower pass bands,
the 1.5 Gband, 1.8 GHz GSM band and 2.4 GHz Bluetooth band, can be
realized by adding three handstand semielliptical-shaped stubs bilaterally at the
upper part of antenna ground. A notched band of 3:3 ~ 3:7 GHz for rejection of
WiMAX radio signals can also be obtained by adjusting the geometry of the
three stubs. In addition, an U-shaped slot on the radiating patch generates a
notched band in 5:15 ~ 5:825 GHz for rejection of WLAN radio signals. The
proposed antenna is designed and built on a FR-4 substrate, with overall size of
25mm X 24 mm. The simulated and measured results are presented and show
that the proposed compact antenna has a stable and omnidirectional radiation
patterns across all the relevant bands.
ANTENNA DESIGN:
The primitive antenna consists of an approximate hexagonal-shaped
radiating patch and an elliptical shaped etched plane, which have a better
impendence matching to cover UWB band.

37
Fig :3.1 Geometry of UWB Antenna
MEASUREMENT:
Based on the design parameters, the proposed antenna structure was
fabricated and tested. The prototype of the proposed antenna was
fabricated on a FR4 substrate (εr = 4:4, tan a = 0:02) with dimension
of 25mm X 24mm and a thickness of 1.6 mm. The fabricated proposed antenna
performance was measured in an Anechoic Chamber with an Agilent E8363B.
The measured reflection coeffcient is compared with the simulated one.
It can be seem that these two results are in good agreement. It is apparent that
the proposed antenna successfully adds three lower pass bands of 1.5 GHz GSM
band, 1.8 GHz GPS band and 2.45 GHz Bluetooth band and two rejection bands
of 3.5 GHz WiMAX and 5.5 GHz WLAN. The return losses of the three lower

38
pass bands are well below -10 dB level, which mean good impedance matches
at these bands.
Fig: 3.2 Return Loss of UWB Antenna

39
Fig: 3.3 Radiation Pattern of UWB Antenna

40
CONCLUSION:
The design of a compact CPW-fed UWB patch antenna with three lower
pass bands and dual-notched bands has been presented. By using three
handstand semielliptical-shaped stubs at the upper part of the ground, three
lower pass bands can be realized for covering GPS, GSM and Bluetooth band,
and a notched band generated in 3:3 » 3:7 GHz for rejection of WiMAX signal
interference. In addition, an inverted U-shape slot on the radiating patch
generates another notched band in 5:15 » 5:825 GHz for rejection of WLAN
signal interference. The proposed antenna have a compact size, stable radiation
pattern, constant group delay and return loss below ¡10 dB over the whole
desirable band. It is a good antenna candidate for personal and mobile UWB
applications due to the features described above.

41
3.2. A NEW DUAL BAND E-SHAPED SLOT ANTENNA DESIGN FOR
WIRELESS APPLICATIONS:
Ali, Jawad K. "A New Dual Band E-shaped Slot Antenna Design for Wireless Applications." PIERS
Proceedings, Suzhou, China September 12 (2011).
Abstract- An E-shaped printed slot antenna is presented as a candidate to cover
dualband operation over the entire wireless local area network (WLAN)
frequency bands of 2.4-2.5 GHz and 4.9-5.8 GHz. The E-shaped slot structure
has been etched in the ground plane, and the 50 microstrip line feed is etched on
the reverse side of the substrate. An additional trapezoidal slot has been etched
attached to the slot structure on the feeding side to facilitate tuning and
the dual-band operation. The antenna structure has been modeled and its
performance has been evaluated using a method of moment based
electromagnetic simulator, IE3D from Zeland Software Inc. Simulation results
show that, the proposed antenna offers good return loss response (for S11
less than -10 dB) at the two bands. The ratio of the two resonating frequencies
f02/f01 could be varied in a considerable range, without changing the antenna
external dimensions, making the antenna suitable for other dual band wireless
applications.
ANTENNA DESIGN
The E-shaped printed slot antenna structure, has been modelled using the
commercially available method of moments based EM simulator, IE3D, from
Zeland Software Inc. The first design step is to make the modelled antenna
resonating such that the lower resonant band is located at 2.45 GHz. This design
goal has been reached by suitable rescaling of the whole structure, varying the
trapezoid dimensions, wt and Lt, and varying the E-shape parameters, wv and
wh.At this step, the proposed antenna has the following dimensions. The E-
shaped slot dimensions are as follows: Lh = 15.52 mm, Lv = 23.38 mm, wh =

42
4:12 mm, and wv = 7.10 mm. The trapezoidal slot dimensions are: the central
length, Lt = 5:4mm the larger width, wt = 4:31 mm, and smaller
width is equal to 3.00 mm, which is the same as that of the microstrip line. A
parametric study has been carried out to demonstrate the e®ect of the slot
internal dimensions, wv and wh on the antenna performance, such that the slot
external dimensions are being held constant.
Fig:3.4 Geometry of E-Shaped Antenna.
-SIMULATION RESULTS:
Observing the influence of the various parameters on the dual band
resonant behaviour of the modelled antenna, it has been found that the dominant
factors in the antenna structure are the E-shaped slot parameters wh and wv,
besides the slot external dimensions.

43
Fig 3.5 Return loss comparison
Figure 3.4 shows that the return loss response of the proposed antenna is highly
affected by the variation of the value of wh with constant value of wv = 7:0 mm.
As the value of wh has been increased, the antenna dual band behaviour is still
maintained. However, the lower resonant frequency has been influenced more
than the higher frequency because of the effect of change of wh. Variation of wv
has a little impact on both the lower and the upper resonant frequencies. Again
the lower resonant frequency is relatively more affected than the higher one.
Fig: 3.6 Radiation Pattern

44
The above figure shows the simulated the electric field radiation patterns Eµ, of
the proposed E-shaped slot antenna for ' = 0± and ' = 90± at: (a) 2.45 GHz, and
(b) 5.8 GHz. The modeled antenna is with slot parameters of wh = 4:12mm and
wv = 7:0 mm.
CONCLUSIONS
A combined E-shaped microstrip printed slot antenna is presented in this
paper, as a candidate for use for dual band wireless applications. The antenna
has been modeled and its performance has been analyzed using a method of
moment based software, IE3D. The proposed antenna shows an interesting dual
band resonant behavior with a wide range of the two resonant frequency ratio
without changing the external.

45
3.3. A MINIATURIZED HILBERT INVERTED-F ANTENNA FOR
WIRELESS SENSOR NETWORK APPLICATIONS
Huang, Jung-Tang, Jia-Hung Shiao, and Jain-Ming Wu. "A miniaturized Hilbert inverted-F antenna for wireless
sensor network applications." Antennas and Propagation, IEEE Transactions on 58.9 (2010): 3100-3103.
Abstract—Miniaturized inverted-F antennas (IFAs) are proposed for wireless
sensor network applications in the 2.45 GHz band. By employing Hilbert
geometry, an overall size reduction of 77% was achieved compared to the
conventional rectangular patch antenna. The proposed antenna can be easily
built in a miniaturized wireless sensor network (WSN). According to the design
rules presented in this paper, antennas can be simulated rapidly. An
experimental prototype of the miniature antenna was fabricated on a 1.6-mm-
thick FR4 substrate. The bandwidth of this antenna less than 10 dB is 220 MHz
(2.32–2.54 GHz) and the percentage of the bandwidth is 9.1%. The peak gain is
1.4 dBi. The measurement results indicate that the antenna shows good
performance.
ANTENNA DESIGN AND SIMULATION:
The geometry of the proposed 2.45 GHz Hilbert IFA is shown in Fig 3.9.
The outline of the antenna was printed on a dielectric substrate that has a
thickness of 0.4 mm, dielectric constant of 4.4, and loss tangent of 0.02. The
ground plane was designed below the transmission line. Hilbert geometry
allows a long electrical length that aids in performing miniaturization.
Furthermore, the modulation of the length of a Hilbert structure can shift the
center frequency. The total size, including the ground plane of the antenna, is 35
mm*6 mm*1.6 mm.

46
Fig 3.7 The geometry of 2.4 GHz Hilbert IFA.
Due to the Hilbert structure and IFA, an antenna size reduction of 77%
was achieved as compared to a conventional rectangular patch antenna. Fig
3.8(a) presents the return loss and Fig 3.8(b) presents the impedance in the
simulation. The center frequency is 2.44 GHz, return loss=29 dB, the simulation
bandwidth of the antenna for less than 10 dB return loss is 230 MHz (2.33–2.56
GHz), and the percentage of the bandwidth is 9.4%. Fig 3.8(c) shows the
radiation pattern of the antenna, which is omni-directional. By adjusting the
distance between the feed and the shorting pin, the impedance can be matched
to 50. Antennas are designed with l=5.8mm, l=6.8mm, and l=7.8 mm. The
simulation results of the return loss with a different l value such as 5.8, 6.8 and
7.8 mm are shown in Fig 3.8.

47
Fig 3.8 Simulation of (a) return loss, (b) impedance plot, and (c) radiation pattern.
MEASUREMENT RESULTS:
The total size, including the ground plane of the antenna, is 35 mm*6
mm*1.6 mm. The return loss is shown in Fig 3.16. The center frequency is at
2.43 GHz, return loss at 27.6 dB, the bandwidth of the antenna for a return loss
less than 10 dB is 200 MHz (2.35–2.55 GHz), and the percentage of the
bandwidth is 9.1%. Figs. 10(a), (b), and (c) present the radiation pattern of this
antenna. The peak gain is 1.4 dBi, slightly better than the simulated result of 1.3
dBi. From theXY, XZ, and YZ radiation patterns of the three planes, we can
observe that that this is an omni-directional antenna confirming that the ground
plane determines the dipole-type pattern.

48
Fig 3.9 The actual construction of the 2.4 GHz Hilbert IFA.
Fig 3.10 Return loss of the 2.4-GHz Hilbert IFA.

49
Fig 3.11 Measurement results for radiation pattern at 2.45 GHz for 2.4 GHz Hilbert IFA (a)
XY plane, (b) XZ plane, and (c) YZ plane, respectively.
CONCLUSION:
The design of the antennas used in WSN is mainly intended to reduce
power, achieve miniaturization, and achieve significant transmission distances.
In this study, we select the Hilbert fractal trace for use as the subject of the
antennas.We can shift the center frequency of the antennas by adjusting the
length of the Hilbert fractal trace because of the advantage of the fractal trace in
increasing the bandwidth; moreover, the characteristics of the antenna can be
improved, while its size can be significantly reduced. The abovementioned
advantages have helped achieve the goal of miniaturizing antennas. With
respect to the design of the 2.4 GHz Hilbert IFA, according to the results of the

50
present study, the equivalent electric capacitance of the antenna increases with a
reduction in the size of the ground plane. Consequently, we need to further
adjust the impedance matching. The lengths of the ground plane and fractal
trace will influence the center frequency of the antenna. Hence, we can improve
the antenna gain by adjusting the length of the ground plane appropriately.

51
3.4. DESIGN AND DEVELOPMENT OF A NOVEL 3-D CUBIC
ANTENNAFOR WIRELESS SENSORNETWORKS (WSNS)AND RFID
APPLICATIONS
Kruesi, Catherine M., Rushi J. Vyas, and Manos M. Tentzeris. "Design and development of a novel 3-D cubic
antenna for wireless sensor networks (WSNs) and RFID applications." Antennas and Propagation, IEEE
Transactions on57.10 (2009): 3293-3299.
Abstract—A novel miniaturized 3-D cubic antenna for use in a wireless sensor
network (WSN) and RFIDs for environmental sensing is introduced. The
antenna produces a truly omnidirectional pattern in both E-plane and H-plane,
which allows for non-intermittent communication that is orientation
independent. The frequency of operation lies in the UHF RFID band, 902 MHz–
928 MHz (centered at 915 MHz). The ultra-compact cubic antenna has
dimensions of 3cm* 3cm *3cm (27 cubic centimeter), which features a length
dimension of lamda/11. The cubic shape of the antenna allows for “smart”
packaging, as sensor equipment may be easily integrated inside the cube’s
hollow (or Styrofoam-filled) interior. The prototype fabrication was performed
on six (planar) sides on liquid crystal polymer (LCP) substrate, and then folded
into the cubic structure. The geometry of the design is inspired by the RFID
inductively coupled meander line structures, which are folded around the sides
of the cube. Due to the large number of freedom degrees, this antenna concept
may be easily reconfigured for many values of impedances and design
parameters. Experimental data verify the simulation results.
CUBIC ANTENNA DESIGN:
Dipole meander line structures have been used for the purpose of size
reduction in UHF antennas Fig. 1 shows the geometry of the meander line for
one dipole arm. The design of Fig. 1(b) is chosen for enhanced bandwidth
performance. Due to the intrinsic operation of the dipole, with current at the

52
ends of the arms going to zero, it is desirable to have less meandering closer to
the feed element where the highest concentration of current is located.
Fig 3.12 Meander line dipole arm structures. (a) Uniform meander line and
(b)nonuniform meander line.
Fig 3.13 Planar meander line structure. Fig 3.14 Graph for planar
meander line antenna shown in
Fig 3.12
Fig 3.15 Folded meander line antenna Fig 3.16 Radiation pattern for the cube
structure

53
The meandering of the dipole arms will allow for minimization in the
length dimension. The data for this antenna is shown in Fig 3.4. The antenna is
resonant at 900 MHz, which corresponds to a dipole length of 16.7 cm. The
radiation pattern at resonance is the typical donut shaped pattern with a
directivity of 2.01 dB. The length of the meander line dipole is 8.9 cm, which is
a 53% reduction in length.
The folding uses the even symmetric configuration. The directivity of this
antenna is 2.2 dB. The radiation pattern obtained for this antenna was Isotropic
shown in the fig 3.5.
FABRICATION AND MEASUREMENTS:
The antenna in Fig 3.4 is fabricated by first performing photolithography
on planar LCP and then folding the T into a cube. For measurements, some
versions of the cube were fabricated around a cube of Styrofoam. The advantage
of using Styrofoam is that its dielectric constant is very close to air, which does
not cause a significant variance to performance, and it enhances the mechanical
stability. Since the application is in a turbulent environment, the Styrofoam
assembly is preferred. The measured along with the simulation S-parameters are
shown in Fig 3.4.
Fig 3.17 S-parameter measurements, measurement compared to simulation data.

54
Fig 3.18 E-phi (solid) and E-theta (dashed) in dB,phi=90degree for cubic antenna fabricated
with Styrofoam
Fig 3.19 E-phi (solid) and E-theta (dashed) in dB, phi=0degree for cubic antenna fabricated
with Styrofoam.
The radiation patterns are shown in Fig 3.5 and Fig 3.6. The full 360
measured radiation pattern (E-total) is shown for the cubic antenna fabricated
with Styrofoam at 915 MHz. The efficiency of the antenna is 75% at 915 MHz
and the maximum gain is 0.53 dBi. The lower efficiency is due to the
unbalanced feed during measurements. If possible the antenna should be
measured with a balun in order to determine correct efficiency. Likewise, the
radiation pattern measurements for the cubic antenna fabricated without
Styrofoam are almost identical to the radiation pattern plots of the antenna with
Styrofoam. The efficiency of this antenna is 72% and the maximum gain is 0.5
dBi.

55
CONCLUSION:
The design, fabrication, and measurement of a cubic antenna with a
nearly isotropic radiation pattern has been achieved. The antenna is matched to
50 in the desired RFID band, and can be reconfigured to match almost any
impedance. The cube can also be used for system-in-package technology,
whereby the antenna provides housing for sensor electronics, providing the
optimum solution for a WSN node. Using this technology, low-cost weather
tracking may be realized, especially in turbulent scenarios, such as tornadoes.
3.5 OBJECTIVE OF PROJECT:
To design an antenna which covers 2.4 GHz and can be used for
wireless sensor networks .

56
CHAPTER 4
4. PROPOSED DESIGN AND SIMULATION RESULT:
4.1. INTRODUCTION:
In the previous chapter we studied about wireless sensor network,
characteristics of WSN, and the advantages of WSN and also studied about
antenna, parameters of antenna and its types, and feeding techniques. Based on
the analysis of previous chapter we designed a planar antenna using CPW feed.
4.2.DESIGN:
The dimensions of the inverted-π antenna are shown in the figure 5.1
Figure 4.1 Geometry of Inverted – π Antenna
The physical dimensions of the designed antenna are 26x32x1.6mm. The FR4
substrate is used whose parameters are
Table 1 Substrate parameters
Permittivity(ɛ) 4.4
Permeability(µ) 1
Loss tangent 0.02
Dielectric
thickness
1.6mm

57
The radiating patch and the ground plane are built on the same side of the
substrate.
4.3. SIMULATION RESULTS:
The structure is simulated using the simulation tool IE3D. The
corresponding VSWR , return loss and the radiation pattern (2D,3D) are
measured.
The return loss is measured in order to calculate how much power is lost
at the load. If the return loss has higher value then it means less power is lost.
For the designed CPW feed antenna the return loss obtained after simulation is
-22.5 dB .
Figure 4.2 Return Loss of Inverted – π Antenna
The VSWR is the measure of mismatch between between the antenna and
the feed. The ideal value of VSWR must be 1, but for practical considerations it
can be between 1 and 2. The simulation result of VSWR is 1.4 dB.

58
Figure 4.3 VSWR of Inverted – π Antenna
The obtained radiation pattern shows a 360o pattern .
(a) (b)
Figure 4.4 (a)3D pattern (b)2D pattern of Inverted – π Antenna

59
CHAPTER 5
5. FABRICATION AND TESTING:
5.1 TOOLS LIST
 Hack Saw
 Skill Saw
 Drill
 Tubing cutter (item#73325,model#14T0180)
 Tubing bender (No. 101-3/8)
5.2 MATERIALS LIST
 4ft. 5/16” Outer diameter coppertubing
 1ft by 2 ft coppersheet(X2)
 1ft by 2 ft plywood board(X2)
 SMA connector(female)
The antenna structure to be built consisted of three main components; a
ground plane, the radiating tubular elements and its coupling counterpart, and a
standardized connection interface for testing on the network analyzer. It was
determined that most suitable material for the structure was copper being that it
was the most accessible of the better conductors. Thus material for the ground
plane and the radiating elements (l-shaped rods) was made out of copper sheet
and copper pipe respectively. For the connection interface a standard female
SMA connector with a solder able lead is used.
5.3. ANTENNA TESTING:
For testing the antenna there are four main characteristics to be
measured; Standing Wave Ratio, efficiency, proximity insensitivity, and
directionality. The standing wave ratio is determined indirectly from the

60
reflection coefficient or S11 parameter of the antenna. The S11 parameter is
immediately obtainable from the network analyzer. The efficiency is measured
by taking the ratio of receiver antenna power output over transmitted antenna
power output. This measurement requires a setup that includes both a
transmitter antenna and receiver antenna where the transmitting antenna has
well known characteristics.
In a similar fashion, directionality can be measured. The basic
procedure is to rotate the receiver antenna in the field of the transmitter antenna
and record the results over the entire 360 degree range. Often this procedure is
performed in an anechoic chamber, to eliminate environmental noise or
reflections that would alter the receiving antennas response. With our antenna
we seek to have an Omni directional response which means having a consistent
gain at all angles relative to the transmitter. Lastly, to measure proximity
insensitivity, the antenna response is measured as a function of distance from a
human body. Ideally, the antenna’s response should not be affected by its
proximity to surrounding objects.
5.4. FABRICATED ANTENNA:
The fabricated antenna is shown in the figure below
Fig. 5.1 Top view of fabricated antenna
The fabricated antenna’s size was compared with a coin dimension as
shown below.

61
Fig.5.2 Size Comparison
5.5. MEASURED RESULTS AND DISCUSSION :
The fabricated antennas were tested using Rhodes and Schwartz , ZVH4
having the frequency range of 100 KHz to 3.6 GHz.
Fig 5.3 Measurement Setup
Measurement has been taken by using network analyzer and compared with the
simulation results. Initially vector network analyzer is calibrated and device is
connected to the analyzer and various parameters are measured.
Fig 5.4 is measured Return Loss and fig 5.5 is measured VSWR of the
proposed antenna.

62
Fig 5.4 Measured Return Loss Fig 5.5 Measured VSWR
The simulation and measured results of the proposed antenna are
compared and debited in fig 5.6. The reveals that there is a slight deviation of
measurement result from the simulated result. This may be due to the effect of
SMA loss and inaccuracy in the fabrication
Fig 5.6 Comparison of measured & simulated results

63
The comparison of measured and simulated results tabulated in the table
2.
The simulated and measured results are tabulated as shown below.
PARAMETERS SIMULATED MEASURED
RETURN LOSS -22.5 dB -24.8 dB
VSWR 1.4 dB 2.27 dB
BANDWIDTH 176 MHz
Table 2 Comparison table
The smith chart for proposed antenna for both simulated and measured
also displayed in fig 5.7 for further validation.
Fig 5.7 Smith Chart(Measured and Simulated)

64
CHAPTER 6
6. CONCLUSION:
The structure of inverted π-shaped patch antenna using conductorbacked
CPW fed was designed and simulated using IE3D software. The simulated
result analysis was compared with the measurement results as discussed earlier.
For , the conductor backed CPW fed inverted π -shaped patch antenna, the
simulated bandwidth obtained was 176 MHz and it is matched with the
measured result. The fabricated antenna resonates at 2.272 GHz with a return
loss of -24.8 dB . Thus the CPW antenna was designed and fabricated which
gives satisfied results.

65
APPENDIX-I
SIMULATION SOFTWARE:
IE3D:
IE3D is a full-wave, method-of-moments based electromagnetic
simulator solving the current distribution on 3D and multilayer structures of
general shape. It has been widely used in the design of MMICs, RFICs, LTCC
circuits, HTS circuits, patch antennas, wire antennas, and other RF/wireless
antennas.
IE3D FEATURES:
1. Modeling true 3D metallic structures in multiple dielectric layers in open,
closed or periodic boundary. There is no limitation on the shape and orientation
of the metallic structures.IE3D can model true 3D structures.
2. Automatic 3D geometry model creation features full support for bond wires,
solder balls & bumps, interconnect and dielectric thicknesses. Proprietary non-
uniform mesh generation and adaptive curve fitting ensure fast and accurate
simulation results for these broadband applications.
3. Reliable simulation results that match measurement reduces your EM design
costs by avoiding expensive design iterations.
4. More simulations-per-hour speeds up design convergence and improves
overall design quality by verifying more design issues in less time.
5. Simulate even your largest structures in the smallest memory footprint
reduces your EM design risks with precise modeling of geometries without
time-consuming error prone design partitioning.

66
6. IE3D SI’s full-wave 3D EM design and verification solution meets the
capacity & run-time performance demands of complete package, PCB or
circuit-level simulation and modeling. The EM-accurate results enable design
and signal integrity (SI) engineers to design and verify their largest designs with
confidence.
7. IE3D SI provides native integration to a variety of popular layout design
tools. Full 3D geometry models of bond wires, solder balls, bumps, vias,
interconnect and dielectric layers are automatically extracted directly from the
layout data and meshed to ensure proper handling by the IE3D SI EM engine.
Now, design and signal integrity engineers are granted easy access to an
accurate EM solution to improve and verify a design’s final performance as part
of their overall EM design practice.
8. IE3D allows users to define the shape of a circuit as optimization variables.
The built-in optimizer will be able to optimize the shape of a structure for best
performance.
9. Visual display of S, Y, and Z-parameters: IE3D comes with the MODUA
post-processor for display of S, Y, and Z-parameters in data list, rectangular
graphs and Smith Chart. MODUA is also a circuit simulator. A user
can graphically connect different S-parameter modules and lumped elements
together and perform a nodal simulation.
10. Flexible utility features and built-in circuit simulator.IE3D comes with
a simple and user-friendly circuit simulator. It includes many simple
and sophisticated utilities such as finding characteristic impedance of a
transmission line, creating the s-parameters for an idealized transmission line,
and back simulation to extract the s-parameters of part of the circuit from a
whole circuit.

67
SYSTEM REQUIREMENTS:
• Windows 32-bit systems
• Windows 64-bit systems
• Linux 32-bit systems (IE3D engine only)
• Linux 64-bit systems (IE3D engine only)

68
APPENDIX-II
SMA CONNECTOR:
SMA (Subminiature version A) connectors are coaxial RF
connectors developed in the 1960s as a minimal connector interface for coaxial
cable with a screw type coupling mechanism. The connector has a 50
Ω impedance. It offers excellent electrical performance from DC to 17 GHz.
CONNECTOR DESIGN:
The SMA connector consists of a 1/4"-36 thread. The male is equipped
with a 0.312" (7.925 mm) hex nut.
In SMA and RP-SMA connectors, the terms "male" and "female" refer
exclusively to the male center pin and its female sleeve counterpart rather than
to the threads that are used to hold the connection in place. The male connector
has inside threads while the female connector has outside threads.
The SMA connector uses a polytetrafluoroethylene (PTFE) dielectric
which will contact along the mating plane. Variability in the construction and
the mating of the connectors limit the repeatability of the connector impedance.
For that reason, an SMA connector is not a good choice for metrological
applications.
VARIATIONS:
The SMA connector is typically rated for mode-free operation from DC
to 18 GHz, though some proprietary versions are rated to 26.5 GHz. For
performance above this, SMA-like connectors are used. These are the 3.5 mm
connector, rated to 34 GHz, and the 2.92 mm (also known as 2.9 mm, SMK, or

69
K type), good up to 46 GHz. These connectors keep the same outside thread as
the SMA, so they can all be cross-mated, however they use an air dielectric,
with the center conductors appropriately scaled. However, the life of the
precision connector will be reduced, and can be easily damaged when mating
with low-grade SMA connectors.
Beyond 46 GHz, the 2.4 mm, 1.85 mm and the 1 mm connector exist.
These are similar to the SMA connector, but with the geometries incompatibly
scaled. These have mode-free operation to 50, 65, and 110 GHz respectively.
Fig AP-2 SMA connector

70
REFERENCES
1. Ali, Jawad K. (2011)."A New Dual Band E-shaped Slot Antenna
Design for Wireless Applications." PIERS Proceedings, Suzhou,
China September 12
2. Huang, Jung-Tang, Jia-Hung Shiao, and Jain-Ming Wu. (2010) "A
miniaturized Hilbert inverted-F antenna for wireless sensor network
applications." Antennasand Propagation, IEEE Transactions
on 58.9): 3100-3103.
3. Shrivastava, Manoj K., A. K. Gautam, and Binod K. Kanaujia. (2014)
"An M‐shaped monopole‐like slot UWB antenna." Microwave and
Optical TechnologyLetters56.1): 127-131.
4. Kruesi, Catherine M., Rushi J. Vyas, and Manos M. Tentzeris. (2009)
"Design and development of a novel 3-D cubic antenna for wireless
sensornetworks (WSNs)and RFID applications." Antennas and
Propagation, IEEE Transactionson57.10): 3293-3299
5. .Luo, Yonglun, et al(2013). "A COMPACT CPW-FED UWB
ANTENNA WITH GSM, GPS, BLUETOOTH AND DUAL
NOTCH BANDS APPLICATIONS." Progress In Electromagnetics
Research C 35
6. Mandal, Tapan, and Santanu Das. (2013). "A COPLANAR
WAVEGUIDE FED ULTRA WIDEBAND HEXAGONAL SLOT
ANTENNA WITH DUAL BAND REJECTION."Progress in
Electromagnetics Research C 39

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7. Nisar, Nuzhat, Shailendra Singh Pawar, and Mohd Sarwar
Raeen.(2012) "A Reciprocal U Shaped Fractal Ultra Wide Band Patch
Antenna."Volume 2, Issue 9, September 2012

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