The document summarizes the work done on antenna design and VHDL coding during a summer training. It describes designing a 1.575 GHz microstrip patch antenna using HFSS software. Key steps included selecting a patch shape and substrate, specifying design requirements, and simulating results. It also provides an introduction to VHDL, describing its basic structure, libraries, modeling styles (behavioral, data flow, structural), and hierarchy. Simulation results showed the antenna achieved less than 2 VSWR and 3.8% bandwidth at the target frequency.

1. SUMMER TRAINING WORK ON
ANTENNA DESIGN & VHDL
Submitted By
Vipin Yadav
2K13-MRCE-MT-ECE-015

2. INDEX
• Antenna Introduction
• HFSS Software
• Patch shapes and substrate
• Design Specifications & Feeding techniques
• Simulation results
• VHDL & Its Coding Styles
• Types of Modelling
• Hierarchy & statements in VHDL

3. INTRODUCTION
• An antenna is an electrical device which converts
electric currents into radio waves, and vice versa. It
is usually used with a radio transmitter or radio
receiver.
• In transmission, a radio transmitter applies an
oscillating radio frequency electric current to the
antenna's terminals, and the antenna radiates the
energy from the current as electromagnetic waves
(radio waves).

4. WHY ANTENNAS ?
• Need of antenna arisen when two person wanted to
communicate between them when separated by some
distance and wired communication is not possible.
• Antennas are required by any radio receiver or
transmitter to couple its electrical connection to the
electromagnetic field.
• Radio waves are electromagnetic waves which carry
signals through the air (or through space) at the
speed of light with almost no transmission loss.

5. HFSS SOFTWARE
• HFSS (high frequency structural simulator) is a high-performance
full-wave electromagnetic(EM) field
simulator for arbitrary 3D volumetric passive device
modelling that takes advantage of the familiar Microsoft
Windows graphical user interface.
• It integrates simulation, visualization, solid modelling,
and automation in an easy-to-learn environment where
solutions to 3D EM problem are quickly and accurately
obtained.
• Ansoft HFSS employs the Finite Element Method(FEM),
adaptive meshing, and brilliant graphics to give
unparalleled performance and insight to all of your 3D EM
problems.

6. Microstrip Antenna
In its most basic form, a Microstrip patch antenna consists of a radiating patch on
one
side of a dielectric substrate which has a ground plane on the other side
For good antenna performance, a thick dielectric substrate having a low dielectric
constant is desirable since this provides better efficiency, larger bandwidth and better
radiation .
Structure of a Microstrip Patch Antenna
 In genaral Micro strip antennas are also
known as
“ PRINTED ANTENNAS ”.
 These are mostly used at microwave
frequencies.
 Because the size of the antenna is directly
tied the wavelength at the resonant
frequency.
 Micro strip patch antenna or patch antenna
is a narrowband wide-beam antenna.

7. Patch Shapes Are:
(a) Single radiating patches
(b) Single slot radiator

8. Substrates are:
The most commonly used substrates are,
1) Honey comb(dielectric constant=1.07)
2)Duroid(dielectric constant=2.32)
3)Quartz(dielectric constant=3.8)
4)Alumina(dielectric constant=10)
 A thicker substrate will increase the radiation
power , reduce conductor loss and improve Band
width.

9. Feeding Techniques:
 Coaxial feed
 Microstrip feed
 Proximity coupled microstrip feed
 Aperture coupled microstrip feed
 Coplanar wave guide
 Line Feed
1-Microstrip Line Feed :
In this type of feed technique, a
conducting strip is connected directly to the
edge of the
microstrip patch.
This kind of feed arrangement has the
advantage that the feed can be etched on
the
same substrate to provide a planar
structure.

10. 2-Coaxial Feed :-
The Coaxial feed or probe feed is a very common
technique used for feeding Microstrip
patch antennas.
Probe fed Rectangular Microstrip
Patch Antenna from top
The main advantage of this type of
feeding scheme is that the feed can be
placed at any
desired location inside the patch in order to
match with its input impedance.
This feed method is easy to fabricate and
has low spurious radiation.
However, its major disadvantage is that it
Coaxial Ground Plane Connector
Substrate
Patch provides narrow bandwidth and is
difficult to model since a hole has to be
drilled in the substrate . and the connector
protrudes outside the ground plane, thus
not making it completely planar for thick
substrates .
Probe fed Rectangular Microstrip Patch Antenna
from side view

11. 3-Aperture Coupled Feed
In this type of feed technique, the radiating
patch and the microstrip feed line are separated
by the ground plane .
Coupling between the patch and the feed
line is made through a slot or an aperture
in the ground plane.
The coupling aperture is usually centered under the Aperture-coupled feed
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.

12. 3.2 Project specifications
Project Specs
Operating Frequency : 1.575 GHz
Input Impedance: 50 Ohm
VSWR: 2:1 @ 1.575 GHz
Polarization: RHCP
Bandwidth: 3.8% (~60 MHz)
Substrate
RT/Duroid (Rogers Corp.)
e= 2.22
h= 125 mils
tan d = 0.001

13. Simulation Results of a 1.575 GHz GPS
Receiver Antenna Design
Return Loss

14. VSWR PLOT
2 D PATTERN

15. VHDL
What does HDL stand for?
HDL is short for Hardware Description Language
(VHDL – VHSIC Hardware Description Language)
(Very High Speed Integrated Circuit)

16. Basic Form of VHDL Code
• Every VHDL design description consists of at least
one entity / architecture pair, or one entity with multiple
architectures.
• The entity section is used to declare I/O ports of the
circuit. The architecture portion describes the circuit’s
behavior.
• A behavioral model is similar to a “black box”.
• Standardized design libraries are included before
entity declaration.

17. Standard Libraries
• Include library ieee; before entity declaration.
• ieee.std_logic_1164 defines a standard for designers
to use in describing interconnection data types used in
VHDL modeling.
• ieee.std_logic_arith provides a set of arithmetic,
conversion, comparison functions for signed,
unsigned, std_ulogic, std_logic, std_logic_vector.
• Ieee.std_logic_unsigned provides a set of unsigned
arithmetic, conversion, and comparison functions for
std_logic_vector.

18. Entity Declaration
• An entity declaration describes the interface of the component.
• PORT clause indicates input and output ports.
• An entity can be thought of as a symbol for a component.

19. Port Declaration
• PORT declaration establishes the interface of the
object to the outside world.
• Three parts of the PORT declaration
• Name
• Any identifier that is not a reserved word.
• Mode
• In, Out, Inout, Buffer
• Data type
• Any declared or predefined datatype.
• Sample PORT declaration syntax:

20. Architecture Declaration
• Architecture declarations describe the operation of the
component.
• Many architectures may exist for one entity, but only one may be
active at a time.
• An architecture is similar to a schematic of the component.

21. Modeling Styles
• There are three modeling styles:
• Behavioral (Sequential)
• Data flow
• Structural

22. VHDL Hierarchy

23. Sequential vs Concurrent Statements
• VHDL provides two different types of
execution: sequential and concurrent.
• Different types of execution are useful for
modeling of real hardware.
• Supports various levels of abstraction.
• Sequential statements view hardware from a
“programmer” approach.
• Concurrent statements are order-independent
and asynchronous.

24. Behavioural Style

25. Data flow Style

26. Structural Style