This document describes the design and construction of a 2-meter or 4-element vertical dipole array antenna with gains of up to 9.7 dBi. The antenna consists of four or two vertical dipoles mounted on a fiberglass mast. Each dipole is made of 1/2 inch copper pipe and is fed individually to maintain 50 ohm impedances. A phasing harness built from 75 ohm coax is used to combine the signals in phase. Testing found communication ranges of up to 15 miles. The antenna breaks down into portable bags for transport and assembly takes under two hours with 2-3 people. The design provides an easy to build high gain antenna for repeater use.
The document discusses different types of oscilloscopes including dual trace CROs, dual beam CROs, digital storage oscilloscopes, and sampling oscilloscopes. A dual trace CRO uses a single electron beam but an electronic switch to display two input signals simultaneously. A dual beam CRO has two separate electron beams and deflection systems allowing two signals to be displayed together in real-time. Digital storage oscilloscopes digitize and store input signals, allowing slow signals to be analyzed. Sampling oscilloscopes take samples from input signals over multiple cycles to display high-frequency signals beyond the bandwidth of its amplifiers.
The document discusses the design of commutators and brushes. It provides details on commutator construction including copper segments insulated by mica. The number of commutator segments equals the number of armature coils. Brush design considerations include the current collected by each brush arm, the brush cross-sectional area based on current density, and using multiple subdivided brushes. A 10-step design procedure is outlined covering commutator dimensions, segment pitch, number of segments, length, brush area, thickness, number of brushes, losses, and limiting the temperature rise.
The document discusses DC machines which can operate as either motors or generators depending on the direction of power flow. A DC machine consists of a static electromagnetic or permanent magnetic field and a rotating armature. The field produces a magnetic medium and the armature produces voltage and torque under the action of the magnetic field. An advantage of DC motors is their speed is easy to control over a wide range, while DC generators are now quite rare. Most DC machines have AC voltages and currents internally but produce DC outputs via a commutator mechanism.
Making a simple variable power supply.
Power supply applications.
Ac and Dc current defintions.
Half wave and full wave rectifier.
Power supply circuit.
Used tools.
Working steps.
Testing.
This document provides information about integrated circuit voltage regulators, including:
1) It defines an IC voltage regulator as an integrated circuit that regulates an unregulated input voltage to provide a constant, regulated output voltage.
2) It classifies IC voltage regulators as either linear or switching regulators, and also as fixed voltage, adjustable voltage, positive voltage, or negative voltage regulators.
3) It provides examples of common IC voltage regulators like the 7805 and LM317, and explains how they regulate voltage.
1. DC motors have a stationary stator that contains electromagnets and a rotating armature.
2. When DC current passes through the electromagnets, it creates a magnetic field that interacts with the magnetic field of the armature coils, producing rotational force.
3. The commutator and brushes ensure that the direction of current in each armature coil remains constant, causing continuous rotation of the armature as each coil's magnetic field switches poles.
This document describes different types of oscillators. It discusses oscillators that use positive feedback to generate AC signals at a desired frequency. It provides block diagrams and explanations of RC phase shift oscillators, Wein bridge oscillators, Hartley oscillators, Colpitts oscillators, and Clapp oscillators. Equations for calculating the oscillation frequency of each type of oscillator are also presented.
The document describes the main construction of DC machines. It lists the two major parts as the stator, which houses the field winding, and the rotor, which rotates in the magnetic field. It then describes the other key parts which include the yoke, poles, field winding, armature winding, commutator, and brushes. The yoke forms a protective covering and carries magnetic flux. The poles contain core and shoe components that produce magnetic flux. The field and armature windings use copper wire to generate electromagnetism. The commutator collects alternating current from the armature and converts it to direct current, while the brushes collect this current.
The document discusses different types of oscilloscopes including dual trace CROs, dual beam CROs, digital storage oscilloscopes, and sampling oscilloscopes. A dual trace CRO uses a single electron beam but an electronic switch to display two input signals simultaneously. A dual beam CRO has two separate electron beams and deflection systems allowing two signals to be displayed together in real-time. Digital storage oscilloscopes digitize and store input signals, allowing slow signals to be analyzed. Sampling oscilloscopes take samples from input signals over multiple cycles to display high-frequency signals beyond the bandwidth of its amplifiers.
The document discusses the design of commutators and brushes. It provides details on commutator construction including copper segments insulated by mica. The number of commutator segments equals the number of armature coils. Brush design considerations include the current collected by each brush arm, the brush cross-sectional area based on current density, and using multiple subdivided brushes. A 10-step design procedure is outlined covering commutator dimensions, segment pitch, number of segments, length, brush area, thickness, number of brushes, losses, and limiting the temperature rise.
The document discusses DC machines which can operate as either motors or generators depending on the direction of power flow. A DC machine consists of a static electromagnetic or permanent magnetic field and a rotating armature. The field produces a magnetic medium and the armature produces voltage and torque under the action of the magnetic field. An advantage of DC motors is their speed is easy to control over a wide range, while DC generators are now quite rare. Most DC machines have AC voltages and currents internally but produce DC outputs via a commutator mechanism.
Making a simple variable power supply.
Power supply applications.
Ac and Dc current defintions.
Half wave and full wave rectifier.
Power supply circuit.
Used tools.
Working steps.
Testing.
This document provides information about integrated circuit voltage regulators, including:
1) It defines an IC voltage regulator as an integrated circuit that regulates an unregulated input voltage to provide a constant, regulated output voltage.
2) It classifies IC voltage regulators as either linear or switching regulators, and also as fixed voltage, adjustable voltage, positive voltage, or negative voltage regulators.
3) It provides examples of common IC voltage regulators like the 7805 and LM317, and explains how they regulate voltage.
1. DC motors have a stationary stator that contains electromagnets and a rotating armature.
2. When DC current passes through the electromagnets, it creates a magnetic field that interacts with the magnetic field of the armature coils, producing rotational force.
3. The commutator and brushes ensure that the direction of current in each armature coil remains constant, causing continuous rotation of the armature as each coil's magnetic field switches poles.
This document describes different types of oscillators. It discusses oscillators that use positive feedback to generate AC signals at a desired frequency. It provides block diagrams and explanations of RC phase shift oscillators, Wein bridge oscillators, Hartley oscillators, Colpitts oscillators, and Clapp oscillators. Equations for calculating the oscillation frequency of each type of oscillator are also presented.
The document describes the main construction of DC machines. It lists the two major parts as the stator, which houses the field winding, and the rotor, which rotates in the magnetic field. It then describes the other key parts which include the yoke, poles, field winding, armature winding, commutator, and brushes. The yoke forms a protective covering and carries magnetic flux. The poles contain core and shoe components that produce magnetic flux. The field and armature windings use copper wire to generate electromagnetism. The commutator collects alternating current from the armature and converts it to direct current, while the brushes collect this current.
A recorder records electrical and non-electrical quantities as a function of time to provide a permanent record that can later be examined and analyzed. Recorders are classified as either analog or digital depending on the type of data acquired. Analog recorders include graphic, oscillographic, and magnetic tape recorders. Graphic recorders display a pen-and-ink record on a chart and can be strip chart or X-Y recorders. Strip chart recorders record one or more variables with respect to time in the form of a continuous curve. X-Y recorders plot one variable as a function of another by using two self-balancing potentiometers to move a recording pen.
The document discusses transistors and bipolar junction transistors (BJTs). It describes:
1. A transistor is a semiconductor device that can amplify or switch electronic signals and electrical power. It has at least three terminals.
2. A BJT has three terminals - base, collector, and emitter. A small current at the base controls a larger current between the collector and emitter, allowing amplification.
3. BJTs come in NPN and PNP types, which differ in the direction of electron flow. Proper biasing of the transistor's junctions is needed to operate it in the active mode for amplification applications.
Do Diodes and electronic stuff freaks you out?And what about those clippers and clampers?The details are as follows.
You can learn every concept related to it here.Enjoy clipping :)
This document is a presentation about function generators. It discusses that a function generator is a device used to generate different types of electrical waveforms over a wide range of frequencies to test electronic equipment. It generates common waveforms like sine, square, triangular, sawtooth, and pulse outputs. Function generators can generate different waveforms up to the megahertz frequency range and are useful for generating test signals in alternating current systems.
Este documento presenta el diseño de un circuito digital para mostrar datos de 8 bits en 4 displays de 7 segmentos utilizando un multiplexor y transistores. Describe el cálculo de las resistencias limitadoras, la selección del transistor 2N2222 y los integrados 74139 y 7404. También incluye la lista de componentes, el diagrama de conexiones y el análisis de la frecuencia máxima de operación. Finalmente, propone implementar un autómata de Moore en VHDL para controlar el cambio de datos y displays a 1 kHz.
El documento describe los diferentes tipos de transistores, incluyendo transistores bipolares de unión (BJT), transistores de efecto de campo de óxido metálico semiconductor (MOSFET), transistor de inducción estática (SIT), transistores bipolares de compuerta aislada (IGBT) y COOLMOS. Luego se enfoca en los BJTs, describiendo su estructura de tres terminales, operación y configuraciones de base común, emisor común y colector común. Finalmente, discute la polarización DC para BJTs.
This document discusses different types of integrated circuit voltage regulators. It describes fixed voltage regulators like the 78XX and 79XX series, which provide positive and negative fixed output voltages, respectively. Adjustable voltage regulators like the LM317 allow the output voltage to be varied. Switching regulators like the MC1723 and LM723 are also covered. Key features and applications of IC voltage regulators are explained, along with basic regulator circuits and their operating principles. Performance parameters like line and load regulation are defined.
- The document discusses equations for calculating the induced EMF in alternator windings.
- It derives the basic EMF equation for a concentrated full-pitched winding as Eph=4.44fTph, where f is frequency, Tph is turns per phase.
- It introduces pitch factor Kp and distribution factor Kd to account for short-pitched and distributed windings.
- The general EMF equation is given as Eph=4.44fTphKpKd, accounting for various winding configurations.
- Examples are given to demonstrate calculating EMF values using the equations.
1. Filters are circuits that pass signals within a specific band of frequencies while rejecting signals outside of that band, known as frequency selectivity. Filters can be passive, using RC, RL, or RLC circuits, or active, using op-amps.
2. Active filters have advantages over passive filters like providing gain without attenuation, high input impedance preventing loading of sources, and low output impedance preventing loading of outputs. They are also easier to adjust and more cost effective.
3. Common types of active filters include low-pass, high-pass, band-pass, and band-stop filters. The number of poles determines the roll-off rate, with each additional pole providing -20dB/decade
Permanent magnet moving iron type instrumentsyash patel
This document discusses permanent magnet moving iron instruments. It describes their construction, working principle, types (attraction and repulsion), uses and advantages. Permanent magnet moving iron instruments work on the principle of magnetic repulsion or attraction between a fixed and moving iron element located in a permanent magnet's field. When current passes through the coil, it produces a torque causing deflection proportional to the current. They are widely used due to their low cost, robustness and accuracy.
An oscillator is an electronic circuit that produces repetitive waveforms without an external input signal. It uses positive feedback to sustain oscillations, with the frequency determined by circuit components like inductors and capacitors. Common types include sinusoidal oscillators that produce sine waves, and relaxation oscillators that produce non-sinusoidal waves like square waves. Oscillators are essential components in many electronic devices and systems to generate stable frequency signals.
The document compares the applications of bipolar junction transistors (BJTs) and field effect transistors (FETs). BJTs are preferred for low current applications and applications requiring high gain and fast response, while FETs are preferred for low voltage, high frequency, and wide load variation applications. FETs also have advantages of lower power consumption, smaller size, stability at high temperatures, and being easier to fabricate at large scale. Key differences are that BJTs require continuous current to remain on while FETs only require a charged gate, and FETs have extremely high input impedance making them suitable for amplifiers.
This document discusses frequency modulation (FM). It begins by defining the angle of a carrier signal and how that angle can be varied to achieve FM or phase modulation. It then provides key details about FM, including that the message signal controls the carrier frequency. The FM signal equation is presented using Bessel functions. Important parameters like modulation index and frequency deviation are defined. Signal waveforms are shown for different input signals. The spectrum of an FM signal is discussed, including the Bessel coefficients and significant sidebands. Narrowband and wideband FM are differentiated. An example of VHF/FM radio transmission parameters is provided. Finally, power in FM signals is addressed.
The document discusses several types of specialized oscilloscopes:
1. Delayed time base oscilloscopes allow studying all parts of a pulse waveform by delaying the signal to the vertical plates. This ensures no part of the waveform is lost.
2. Analog storage oscilloscopes can retain an image for longer periods through mesh or phosphor storage techniques, allowing viewing of very low frequency waveforms.
3. Sampling oscilloscopes use a staircase-ramp generator to take samples that are displayed as the beam moves across the screen. Synchronization ensures sampling is timed with the input signal frequency.
4. Digital storage oscilloscopes digitize the input signal using an analog-to-
The document discusses the cathode ray oscilloscope (CRO). It begins with an introduction that describes a CRO as an electronic device that uses a cathode ray tube to generate visible patterns and graphs on a screen. It then provides details about the basic blocks of a CRO including the vertical and horizontal amplifiers, trigger circuit, time-base generator, and cathode ray tube. Applications of CROs include viewing waveforms, measuring frequency and voltage, and circuit design and testing. Advantages include high resolution and contrast while disadvantages include size, power consumption, and complexity.
The document discusses different types of multivibrators, including bistable, monostable, and astable multivibrators. A multivibrator is an electronic circuit that generates non-sinusoidal oscillations using switching elements like transistors. Bistable multivibrators have two stable states, monostable multivibrators have one stable state and need a trigger, and astable multivibrators have no permanent stable states and oscillate continuously between two quasi-stable states. Common applications include using bistable multivibrators as memory elements, monostable multivibrators as timing circuits, and astable multivibrators as square wave generators.
El primer documento describe un circuito para atraer peces usando un micrófono magnético. El segundo presenta un amplificador de 1/2W para sistemas de intercomunicación. El tercer circuito es un amplificador con ganancia de 1000 usando un operacional.
Hybrid pi model of a Transistor. And designing of pi model using transistor with internal capacitances & internal resistance default considerations. along with CE short channel current gain with and without load. and also FET analysis its equivalent circuits.in FET analysis we have common source and common drain type of systems along with their equivalent circuits and analysis. capture these images and findout the solution for your hybid pi model high frequncy nature of a transistor. All the best. keep in contact with my linkedin.
This document describes a circuit design that can generate variable frequency and duty cycle output signals. It uses a crystal oscillator followed by counters and multiplexers to select different divisions of the oscillator frequency. The frequency and duty cycle can be independently controlled. Test results showed the circuit can clearly produce telephone speech through a small speaker.
It was our first real life based designing experience on this platform. From the mentioned designed we tried to develop a prototype of Dipole antenna of 600 Mhz for practical uses. For the further development we’ve a got plan to use a simulation software like CST microwave studio or ADS to simulate our developed design in the long term . We had to work very hard to complete this design in time! But in the end, the challenge and learning experience were well worth it.
A recorder records electrical and non-electrical quantities as a function of time to provide a permanent record that can later be examined and analyzed. Recorders are classified as either analog or digital depending on the type of data acquired. Analog recorders include graphic, oscillographic, and magnetic tape recorders. Graphic recorders display a pen-and-ink record on a chart and can be strip chart or X-Y recorders. Strip chart recorders record one or more variables with respect to time in the form of a continuous curve. X-Y recorders plot one variable as a function of another by using two self-balancing potentiometers to move a recording pen.
The document discusses transistors and bipolar junction transistors (BJTs). It describes:
1. A transistor is a semiconductor device that can amplify or switch electronic signals and electrical power. It has at least three terminals.
2. A BJT has three terminals - base, collector, and emitter. A small current at the base controls a larger current between the collector and emitter, allowing amplification.
3. BJTs come in NPN and PNP types, which differ in the direction of electron flow. Proper biasing of the transistor's junctions is needed to operate it in the active mode for amplification applications.
Do Diodes and electronic stuff freaks you out?And what about those clippers and clampers?The details are as follows.
You can learn every concept related to it here.Enjoy clipping :)
This document is a presentation about function generators. It discusses that a function generator is a device used to generate different types of electrical waveforms over a wide range of frequencies to test electronic equipment. It generates common waveforms like sine, square, triangular, sawtooth, and pulse outputs. Function generators can generate different waveforms up to the megahertz frequency range and are useful for generating test signals in alternating current systems.
Este documento presenta el diseño de un circuito digital para mostrar datos de 8 bits en 4 displays de 7 segmentos utilizando un multiplexor y transistores. Describe el cálculo de las resistencias limitadoras, la selección del transistor 2N2222 y los integrados 74139 y 7404. También incluye la lista de componentes, el diagrama de conexiones y el análisis de la frecuencia máxima de operación. Finalmente, propone implementar un autómata de Moore en VHDL para controlar el cambio de datos y displays a 1 kHz.
El documento describe los diferentes tipos de transistores, incluyendo transistores bipolares de unión (BJT), transistores de efecto de campo de óxido metálico semiconductor (MOSFET), transistor de inducción estática (SIT), transistores bipolares de compuerta aislada (IGBT) y COOLMOS. Luego se enfoca en los BJTs, describiendo su estructura de tres terminales, operación y configuraciones de base común, emisor común y colector común. Finalmente, discute la polarización DC para BJTs.
This document discusses different types of integrated circuit voltage regulators. It describes fixed voltage regulators like the 78XX and 79XX series, which provide positive and negative fixed output voltages, respectively. Adjustable voltage regulators like the LM317 allow the output voltage to be varied. Switching regulators like the MC1723 and LM723 are also covered. Key features and applications of IC voltage regulators are explained, along with basic regulator circuits and their operating principles. Performance parameters like line and load regulation are defined.
- The document discusses equations for calculating the induced EMF in alternator windings.
- It derives the basic EMF equation for a concentrated full-pitched winding as Eph=4.44fTph, where f is frequency, Tph is turns per phase.
- It introduces pitch factor Kp and distribution factor Kd to account for short-pitched and distributed windings.
- The general EMF equation is given as Eph=4.44fTphKpKd, accounting for various winding configurations.
- Examples are given to demonstrate calculating EMF values using the equations.
1. Filters are circuits that pass signals within a specific band of frequencies while rejecting signals outside of that band, known as frequency selectivity. Filters can be passive, using RC, RL, or RLC circuits, or active, using op-amps.
2. Active filters have advantages over passive filters like providing gain without attenuation, high input impedance preventing loading of sources, and low output impedance preventing loading of outputs. They are also easier to adjust and more cost effective.
3. Common types of active filters include low-pass, high-pass, band-pass, and band-stop filters. The number of poles determines the roll-off rate, with each additional pole providing -20dB/decade
Permanent magnet moving iron type instrumentsyash patel
This document discusses permanent magnet moving iron instruments. It describes their construction, working principle, types (attraction and repulsion), uses and advantages. Permanent magnet moving iron instruments work on the principle of magnetic repulsion or attraction between a fixed and moving iron element located in a permanent magnet's field. When current passes through the coil, it produces a torque causing deflection proportional to the current. They are widely used due to their low cost, robustness and accuracy.
An oscillator is an electronic circuit that produces repetitive waveforms without an external input signal. It uses positive feedback to sustain oscillations, with the frequency determined by circuit components like inductors and capacitors. Common types include sinusoidal oscillators that produce sine waves, and relaxation oscillators that produce non-sinusoidal waves like square waves. Oscillators are essential components in many electronic devices and systems to generate stable frequency signals.
The document compares the applications of bipolar junction transistors (BJTs) and field effect transistors (FETs). BJTs are preferred for low current applications and applications requiring high gain and fast response, while FETs are preferred for low voltage, high frequency, and wide load variation applications. FETs also have advantages of lower power consumption, smaller size, stability at high temperatures, and being easier to fabricate at large scale. Key differences are that BJTs require continuous current to remain on while FETs only require a charged gate, and FETs have extremely high input impedance making them suitable for amplifiers.
This document discusses frequency modulation (FM). It begins by defining the angle of a carrier signal and how that angle can be varied to achieve FM or phase modulation. It then provides key details about FM, including that the message signal controls the carrier frequency. The FM signal equation is presented using Bessel functions. Important parameters like modulation index and frequency deviation are defined. Signal waveforms are shown for different input signals. The spectrum of an FM signal is discussed, including the Bessel coefficients and significant sidebands. Narrowband and wideband FM are differentiated. An example of VHF/FM radio transmission parameters is provided. Finally, power in FM signals is addressed.
The document discusses several types of specialized oscilloscopes:
1. Delayed time base oscilloscopes allow studying all parts of a pulse waveform by delaying the signal to the vertical plates. This ensures no part of the waveform is lost.
2. Analog storage oscilloscopes can retain an image for longer periods through mesh or phosphor storage techniques, allowing viewing of very low frequency waveforms.
3. Sampling oscilloscopes use a staircase-ramp generator to take samples that are displayed as the beam moves across the screen. Synchronization ensures sampling is timed with the input signal frequency.
4. Digital storage oscilloscopes digitize the input signal using an analog-to-
The document discusses the cathode ray oscilloscope (CRO). It begins with an introduction that describes a CRO as an electronic device that uses a cathode ray tube to generate visible patterns and graphs on a screen. It then provides details about the basic blocks of a CRO including the vertical and horizontal amplifiers, trigger circuit, time-base generator, and cathode ray tube. Applications of CROs include viewing waveforms, measuring frequency and voltage, and circuit design and testing. Advantages include high resolution and contrast while disadvantages include size, power consumption, and complexity.
The document discusses different types of multivibrators, including bistable, monostable, and astable multivibrators. A multivibrator is an electronic circuit that generates non-sinusoidal oscillations using switching elements like transistors. Bistable multivibrators have two stable states, monostable multivibrators have one stable state and need a trigger, and astable multivibrators have no permanent stable states and oscillate continuously between two quasi-stable states. Common applications include using bistable multivibrators as memory elements, monostable multivibrators as timing circuits, and astable multivibrators as square wave generators.
El primer documento describe un circuito para atraer peces usando un micrófono magnético. El segundo presenta un amplificador de 1/2W para sistemas de intercomunicación. El tercer circuito es un amplificador con ganancia de 1000 usando un operacional.
Hybrid pi model of a Transistor. And designing of pi model using transistor with internal capacitances & internal resistance default considerations. along with CE short channel current gain with and without load. and also FET analysis its equivalent circuits.in FET analysis we have common source and common drain type of systems along with their equivalent circuits and analysis. capture these images and findout the solution for your hybid pi model high frequncy nature of a transistor. All the best. keep in contact with my linkedin.
This document describes a circuit design that can generate variable frequency and duty cycle output signals. It uses a crystal oscillator followed by counters and multiplexers to select different divisions of the oscillator frequency. The frequency and duty cycle can be independently controlled. Test results showed the circuit can clearly produce telephone speech through a small speaker.
It was our first real life based designing experience on this platform. From the mentioned designed we tried to develop a prototype of Dipole antenna of 600 Mhz for practical uses. For the further development we’ve a got plan to use a simulation software like CST microwave studio or ADS to simulate our developed design in the long term . We had to work very hard to complete this design in time! But in the end, the challenge and learning experience were well worth it.
The document discusses different types of small antennas that can be used for EnOcean-based products, including quarter-wave monopole antennas, helical antennas, chip antennas, and PCB antennas. It emphasizes that the antenna design is critical for RF performance and range. A quarter-wave monopole antenna provides good overall performance but may be too long at lower frequencies. A helical antenna can significantly reduce the size while maintaining good performance. PCB antennas can be a low-cost solution if enough ground plane is available. The size and shape of the ground plane is important for all these antenna types to function properly.
The document discusses various types of small antennas that can be used for EnOcean-based products, including quarter-wave monopole antennas, helical antennas, chip antennas, and PCB antennas. It emphasizes that the antenna design is critical for radio performance and range. The antenna and a sufficiently sized ground plane form a resonant circuit. Common pitfalls in antenna design are an undersized ground plane or traces and components placed too close to the antenna.
The document discusses small loop antennas, also known as magnetic dipole antennas. It provides details on:
1) The vector magnetic potential, current density, and electric and magnetic fields generated by a small loop antenna. The fields are similar to those of a Hertzian dipole.
2) Key parameters of small loop antennas including power density, directivity, total radiated power, and radiation resistance. Increasing the diameter or using a ferrite core can increase the antenna's efficiency.
3) Practical examples of small loop antennas including a precision VLF antenna coil and an AM/LW loopstick antenna for tuning between 100 kHz to 1710 kHz when used with a variable capacitor.
The document discusses small loop antennas, also known as magnetic dipole antennas. It provides details on:
1) The vector magnetic potential, current density, and electric and magnetic fields generated by a small loop antenna. The fields are similar to those of a Hertzian dipole.
2) Key parameters of small loop antennas including power density, directivity, total radiated power, and radiation resistance. Increasing the diameter or using a ferrite core can increase the antenna's efficiency.
3) Practical examples of small loop antennas including a precision VLF antenna coil and an AM/LW loopstick antenna for tuning between 100 kHz to 1710 kHz when used with a variable capacitor.
The document discusses small loop antennas, also known as magnetic dipole antennas. It provides details on:
1) The vector magnetic potential, current density, and electric and magnetic fields generated by a small loop antenna. The fields are similar to those of a Hertzian dipole.
2) Key parameters of small loop antennas including power density, directivity, total radiated power, and radiation resistance. Increasing the diameter or using a ferrite core can increase the antenna's efficiency.
3) Practical examples of small loop antennas including a precision VLF antenna coil and an AM/LW loopstick antenna for tuning between 100 kHz to 1710 kHz when used with a variable capacitor.
The document summarizes different types of antennas used in radio transmission and reception. It discusses wire antennas, including random wire antennas; travelling wave antennas like the Beverage and rhombic antennas; log-periodic antennas; aperture antennas; reflector antennas; microstrip antennas; and antennas used for television reception, like dipole and loop indoor antennas and yagi and log periodic outdoor antennas. It also provides details on how to design and install different antennas for use on various radio bands.
This document provides information on sizing junction boxes and determining conductor bending radii according to NEC standards. It discusses the definitions and formulas for calculating junction box length and width based on conduit sizes and configurations. Minimum bending radii requirements are presented for various sized conductors and fiber optic cables. Quiz questions are also included at the end to test comprehension.
Tech Vidhya is the premier IT and Telecom training institute of India that is running its quality training courses since last decade and we deliver what we promise. Tech Vidhya is the leading training institute in telecom and IT sector that offers various Telecom, telecommunication, Networking and IT/Software courses in an efficient and friendly manner. We are having the highly qualified and experienced trainers for all the courses. The trainers are updated with the latest technologies and they are working on various live projects on India’s top telecom/IT companies.
Dual band microstrip antenna with slit load design for wireless local area ne...BASIM AL-SHAMMARI
This paper presents a design of dual frequency band operation nearly square patch antenna
for IEEE 802.11b,g (2.4Ghz-2.4835GHz) and IEEE 802.11a (5.15GHz-5.25GHz)by using a patch
antenna. The patch and ground plane are separated by a substrate; the radiating patch have two pairs
of orthogonal slits cut from the edge, this antenna has wide bandwidth in the frequency band of
(WLAN) and with a return loss ≤ −10 dB from 2.4 GHz to 2.48 GHz and from 5.12 GHz to 5.32
GHz exhibits circularly polarized far field radiation pattern. The proposed antennas have been
simulated and analyzed using method of moments (MoM) based software package Microwave
Office 2009 v9.0. The results show that the antenna has dual band frequency operation by using slit
load.
Dual band microstrip antenna with slit load design for wireless local area ne...BASIM AL-SHAMMARI
This paper presents a design of dual frequency band operation nearly square patch antenna
for IEEE 802.11b,g (2.4Ghz-2.4835GHz) and IEEE 802.11a (5.15GHz-5.25GHz)by using a patch
antenna. The patch and ground plane are separated by a substrate; the radiating patch have two pairs
of orthogonal slits cut from the edge, this antenna has wide bandwidth in the frequency band of
(WLAN) and with a return loss ≤ −10 dB from 2.4 GHz to 2.48 GHz and from 5.12 GHz to 5.32
GHz exhibits circularly polarized far-field radiation pattern. The proposed antennas have been
simulated and analyzed using method of moments (MoM) based software package Microwave
Office 2009 v9.0. The results show that the antenna has dual-band frequency operation by using slit
load.
This document summarizes different types of telecom cables used in telecommunications including:
- Twisted pair cables like UTP and STP used for voice and data circuits. UTP is unshielded and cheaper while STP is shielded and protects against interference.
- Fiber optic cables (OFC) used for high bandwidth data communication. OFC has huge bandwidth, is secure, flexible and has low attenuation but requires specialized equipment and skills for installation and maintenance.
- Switchboard cables used for indoor circuits with various conductor sizes and color coding schemes. Testing includes checking insulation, resistance and attenuation periodically.
- Outdoor cables like quad cable used for signaling circuits between stations. It has four balanced conduct
This article introduces the design of the antenna and recommends two tested low-cost PCB antennas. These PCB antennas can be used with Bluetooth Low Energy (BLE) solutions. For the best performance, BLE and BLE 2.4GHz radio frequencies must be correctly matched to their antennas.
Frequency-independent (FI) antennas are radiating structures capable of maintaining consistent impedance and pattern characteristics over multiple-decade bandwidths. Their finite size limits the lowest frequency of operation, and the finite precision of the center region bounds the highest frequency of operation.
Two-section branch-line hybrid couplers based broadband transmit/receive switchIJECEIAES
This article introduces a broadband microstripline-based transmit/receive switch for 7-Tesla magnetic resonance imaging. The designed switch aims to handle a signal of multiple frequencies to/from a multi-tuned radio-frequency coil that resonates at frequencies corresponding to the speed of precession of a wide range of atomic X-nuclei, at the same time and without tuning. These include 1H, 23Na, 13C, 31P, 19F, and 7Li used in magnetic resonance spectroscopy as a measure to the existence of many diseases. The fundamental and third harmonic center frequencies of the switch are adjusted to resonate at two broadbands covering a wide range of atomic X-nuclei. Two section branch-line hybrid couplers with phase inverters are designed to build the broadband switch. The designed switch used the minimum trace widths of transmission lines that reveal a compact size without increasing the heat and then the loss beyond specific values. The couplers and the switch S-parameters exhibited good return loss (<-10 dB), high isolation (<-40 dB), less insertion loss (<1 dB) and two clear wide bands covering many atomic X-nuclei used in diagnosis, at the same time and without the need for any tuning circuit during operation.
This document is a project report for an FM radio receiver circuit built by a student named Sourabh Kant in Class XII. It includes a cover page with Sourabh's details, a certificate signed by his teacher certifying the completion of the project, an acknowledgement thanking his teacher for guidance, and several sections describing the circuit design and components. The circuit uses an IC chip and few other passive components to receive FM radio signals and output audio to headphones. Diagrams and pictures show the circuit layout.
hello readers i give my PPT presentation for about antenna and ther properties and working explain in this ppt
i hope you like it THANK YOU.......!!!!!!!
This document summarizes the principles of biofeedback training and its clinical applications. It discusses how biofeedback devices can help people learn to control normally involuntary bodily processes like heart rate and muscle tension by using electronic sensors to provide feedback on these internal processes. The feedback loop allows people to consciously influence their body in new ways. Biofeedback is being researched for reducing muscle tension headaches, lowering blood pressure, and gaining control over other bodily functions.
This document discusses core material selection for baluns and transformers. It recommends using lower permeability cores like 73 material for receiving applications up to 30 MHz due to their lower turns count. For high power applications, even lower permeability cores like 65 or 61 material are recommended due to their higher Curie temperatures and lower losses. The core's internal length parallel to the conductor has the largest effect on impedance, while diameter and thickness have smaller effects. Minimizing conductor length outside the core window improves performance. Binocular and stacked cores are preferred to minimize external conductor length. Measurements show phase inversion transformers and Beverage matching transformers perform well with the recommended core materials and designs.
The document discusses various types of antennas used for land mobile radio (LMR) systems, including:
- Dipoles and monopoles, which are basic omnidirectional antennas. Vertical monopoles mounted on vehicles are commonly used.
- Directional antennas like corner reflectors, Yagi antennas, and log-periodic antennas that have higher gain but more directional patterns.
- Arrays of multiple antenna elements that have higher gain and narrower beamwidths than a single element. Common array designs include stacked dipoles and coaxial collinear arrays.
- Unusual antennas like aperture antennas and slot antennas that can be concealed but have different performance tradeoffs than basic wire antennas.
- Active antennas
A balun is used to connect an unbalanced transmission line, like coaxial cable, to a balanced antenna. Without a balun, the currents on each side of the balanced antenna would not be equal, causing improper operation. A balun forces the outer current on the coaxial cable to be zero, which balances the currents on each side of the antenna. There are different types of baluns that can be used to choke off the outer current, including sleeve baluns, folded baluns, tapered baluns, and infinite baluns. Baluns ensure balanced operation between an unbalanced transmission line and a balanced antenna component.
The design of ultra wideband antennas close to the fundamental limitvilla1451
The document discusses the design of an ultra-wideband antenna with performance close to the theoretical fundamental limit. It begins by re-examining Chu's equivalent circuit model for spherical modes, which suggests the concept of an ideal antenna characterized by an entire function and two complex poles. An antenna design strategy is proposed based on the characteristics of the ideal antenna. The design process evolves a capacitively-coupled hemispherical helix with a cone feed, which demonstrates a 10:1 impedance bandwidth while maintaining a size of 1/8 wavelength, close to the theoretical limit.
Smart antennas for next generation wireless systems eurasipvilla1451
This document is an editorial for a special issue of the EURASIP Journal on Wireless Communications and Networking on smart antennas for next generation wireless systems. It introduces the topic and provides a brief overview of some of the papers included in the issue. These papers address critical aspects of smart antenna implementation and development, including antenna array design, measurements, channel modeling, and interference-aware system optimization. The editorial highlights key contributions on topics such as tower-top antenna array calibration, uniform rectangular array design for line-of-sight MIMO channels, mutual coupling estimation in antenna arrays, and cellular system throughput enhancement through nonuniform antenna spacing.
This document summarizes the development of small antennas for modern wireless communications. It discusses four key antenna technologies: 1) multiband planar inverted-F antennas (PIFAs) which can be made multiband through slots/branches, 2) broadband folded patch antennas which use folding and slots to generate multiple resonances and bandwidths over 100%, 3) compact differentially fed dipole and loop antennas which use techniques like meandering and capacitive loading for size reduction, and 4) miniature circularly polarized patch antennas which employ techniques like slots, slits, folding and shorting pins to reduce size while maintaining radiation patterns. The goal is to provide context and perspectives on small antenna designs and technologies.
The dynamical-casimir-effect-in-superconducting-microwave-circuitsvilla1451
This document proposes investigating the dynamical Casimir effect in superconducting electrical circuits based on microfabricated waveguides. It describes two proposed circuit configurations: (1) an open waveguide circuit corresponding to a single moving mirror, and (2) a resonator coupled to a waveguide corresponding to a single-sided cavity. The document analyzes how photon flux, output field correlations, and squeezing spectra in these circuits could be used to distinguish radiation from the dynamical Casimir effect from other sources like thermal noise.
A transmission line based technique for de-embedding noise parametersvilla1451
This document presents a transmission line-based technique for de-embedding noise parameters of transistors from measured S-parameter data. The technique accounts for the distributed effects of interconnect lines and pad-interconnect discontinuities. It requires only two transmission line test structures to de-embed all devices in a process, making it area-efficient. The technique is validated experimentally on 90nm and 130nm n-MOSFETs and SiGe HBTs. Results are compared to other lumped and distributed de-embedding methods.
The document discusses advances in differential probing technology that can capture high frequency signals with low loading effects. It begins by explaining the limitations of single-ended probes in measuring signals with varying grounds and introduces differential probes as a solution. It then describes a new class of differential probes that have the lowest loading of any previous probe due to advances that reduced inductance and capacitance. Charts are presented comparing the impedance profiles of the new differential probes to previous single-ended probes, showing the differential design maintains a much higher input impedance even at very high frequencies.
This document reviews optical SETI (OSETI) programs past, present, and future. It discusses how the field of OSETI regained respectability in the late 20th century after a 25-year hiatus due to a historical accident, not a lack of technology. It describes some examples of commercial detection equipment that can be used for OSETI searches. It also speculates that OSETI may come to dominate the electromagnetic search for extraterrestrial intelligence on Earth by the end of the first decade of the 21st century as telescopes are employed in the optical search and dedicated OSETI observatories are established.
This chapter describes the development and use of the false alarm rate (FAR) as the detection statistic for analyzing data from LIGO's fifth science run. The FAR allows searches over a large parameter space without being limited by a high background false alarm rate from a smaller subregion. Triggers are divided into categories based on coincidence type, mass parameters, and applied vetoes to account for different background rates. The FAR is calculated for each trigger based on the number of background triggers with equal or higher ranking. Combining trigger categories yields a combined false alarm rate (FARc) that improves detection efficiency compared to other statistics like combined SNR.
Sri Guru Hargobind Ji - Bandi Chor Guru.pdfBalvir Singh
Sri Guru Hargobind Ji (19 June 1595 - 3 March 1644) is revered as the Sixth Nanak.
• On 25 May 1606 Guru Arjan nominated his son Sri Hargobind Ji as his successor. Shortly
afterwards, Guru Arjan was arrested, tortured and killed by order of the Mogul Emperor
Jahangir.
• Guru Hargobind's succession ceremony took place on 24 June 1606. He was barely
eleven years old when he became 6th Guru.
• As ordered by Guru Arjan Dev Ji, he put on two swords, one indicated his spiritual
authority (PIRI) and the other, his temporal authority (MIRI). He thus for the first time
initiated military tradition in the Sikh faith to resist religious persecution, protect
people’s freedom and independence to practice religion by choice. He transformed
Sikhs to be Saints and Soldier.
• He had a long tenure as Guru, lasting 37 years, 9 months and 3 days
This study Examines the Effectiveness of Talent Procurement through the Imple...DharmaBanothu
In the world with high technology and fast
forward mindset recruiters are walking/showing interest
towards E-Recruitment. Present most of the HRs of
many companies are choosing E-Recruitment as the best
choice for recruitment. E-Recruitment is being done
through many online platforms like Linkedin, Naukri,
Instagram , Facebook etc. Now with high technology E-
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Artificial Intelligence too.
Key Words : Talent Management, Talent Acquisition , E-
Recruitment , Artificial Intelligence Introduction
Effectiveness of Talent Acquisition through E-
Recruitment in this topic we will discuss about 4important
and interlinked topics which are
We have designed & manufacture the Lubi Valves LBF series type of Butterfly Valves for General Utility Water applications as well as for HVAC applications.
Applications of artificial Intelligence in Mechanical Engineering.pdfAtif Razi
Historically, mechanical engineering has relied heavily on human expertise and empirical methods to solve complex problems. With the introduction of computer-aided design (CAD) and finite element analysis (FEA), the field took its first steps towards digitization. These tools allowed engineers to simulate and analyze mechanical systems with greater accuracy and efficiency. However, the sheer volume of data generated by modern engineering systems and the increasing complexity of these systems have necessitated more advanced analytical tools, paving the way for AI.
AI offers the capability to process vast amounts of data, identify patterns, and make predictions with a level of speed and accuracy unattainable by traditional methods. This has profound implications for mechanical engineering, enabling more efficient design processes, predictive maintenance strategies, and optimized manufacturing operations. AI-driven tools can learn from historical data, adapt to new information, and continuously improve their performance, making them invaluable in tackling the multifaceted challenges of modern mechanical engineering.
Impartiality as per ISO /IEC 17025:2017 StandardMuhammadJazib15
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Supermarket Management System Project Report.pdfKamal Acharya
Supermarket management is a stand-alone J2EE using Eclipse Juno program.
This project contains all the necessary required information about maintaining
the supermarket billing system.
The core idea of this project to minimize the paper work and centralize the
data. Here all the communication is taken in secure manner. That is, in this
application the information will be stored in client itself. For further security the
data base is stored in the back-end oracle and so no intruders can access it.
Prediction of Electrical Energy Efficiency Using Information on Consumer's Ac...PriyankaKilaniya
Energy efficiency has been important since the latter part of the last century. The main object of this survey is to determine the energy efficiency knowledge among consumers. Two separate districts in Bangladesh are selected to conduct the survey on households and showrooms about the energy and seller also. The survey uses the data to find some regression equations from which it is easy to predict energy efficiency knowledge. The data is analyzed and calculated based on five important criteria. The initial target was to find some factors that help predict a person's energy efficiency knowledge. From the survey, it is found that the energy efficiency awareness among the people of our country is very low. Relationships between household energy use behaviors are estimated using a unique dataset of about 40 households and 20 showrooms in Bangladesh's Chapainawabganj and Bagerhat districts. Knowledge of energy consumption and energy efficiency technology options is found to be associated with household use of energy conservation practices. Household characteristics also influence household energy use behavior. Younger household cohorts are more likely to adopt energy-efficient technologies and energy conservation practices and place primary importance on energy saving for environmental reasons. Education also influences attitudes toward energy conservation in Bangladesh. Low-education households indicate they primarily save electricity for the environment while high-education households indicate they are motivated by environmental concerns.
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2 meter vertical dipole array
1. A 2-Meter Vertical Dipole Array, KG4JJH Page 1 of 6
A 2-Meter Vertical Dipole Array
Build this 2 or 4-Element VHF repeater antenna with up to 9.7 dBi
gain and 18° Vertical Beamwidth.
ost commercial 2-meter repeater antennas with gain fall into two categories:
collinear arrays and stacked element arrays, with gains ranging from 3 to 9 dB1
.
The higher gain antennas have a lower vertical beamwidth. For example, a
typical 4-element exposed dipole offset array with 9 dB gain has a vertical beamwidth of
16°. This is the angle above and below the horizon at which the signal is half the
strength (-3 dB) of the signal at the horizon. In general, high gain antennas work best
from low level sites, or high elevation sites far away from the targeted area. For high
sites near the target area, a lower gain antenna with a higher vertical beamwidth is used.
This prevents the signal from passing over the target area.2
Exposed dipole arrays fall into the stacked element array category. They resemble
folded dipoles and their construction often requires tube bending, welding, or special
brackets. Coaxial collinear arrays (made from coax) are easier to build but do not break
down into convenient lengths for transporting. Vertical dipole arrays built from individual
and unconnected center-fed dipoles are among the simplest to construct but can be
difficult to feed. Unless each feedline is routed a significant distance away from the
antenna at a 90° angle, feedline coupling will distort the radiation pattern.
With these ideas in mind, I began modeling antennas in search of an easy to build, all
metal, vertical dipole array. The antenna that emerged from these modeling sessions
consists of four vertical dipoles, each centered on a 60 inch vertical section. While the
array can be built using a variety of methods and materials, a copper pipe version is
presented here. The array is offset3
, with all elements and maximum gain on the same
side of the mast. In addition to 9.7 dBi gain, each dipole is 50Ω, allowing the phasing
harness to be built from readily available 75Ω coax. The phasing harness sections are
strapped to each dipole, minimizing feedline coupling and pattern distortion. For high
elevation sites near the target area, one-half of the array can be used to provide less
gain (6.85 dBi) and a higher vertical beamwidth (36°).
Antenna Construction
The array can be built using four identical dipoles. However, the length and feedpoint
impedance of each dipole is influenced by its location in the array. Inner sections are
affected by the outer section on both sides and hence differ in impedance from the outer
sections, which are affected on only one side. In order for the phasing harness to work
correctly, each antenna in the array should be as close as possible to 50Ω at the
resonant frequency4
. For this reason, each dipole in the array has been optimized. (See
individual SWR plots, attachment 2 of 9).
The array is built entirely from ½ inch copper pipe and fittings and is 20 feet tall.
However, due to the weight of copper pipe it must be supported (or hung) from a tower
or fastened to a non-metallic mast. To construct the 4-element array you will need 35
feet of ½ inch type L copper pipe, eight ½ inch copper tees, ten ½ inch copper caps,
M
2. A 2-Meter Vertical Dipole Array, KG4JJH Page 2 of 6
three ½ inch unions, and 12 inches of ¼ inch PVC pipe (0.540 inch OD). The caps are
optional and are for the prevention of mud dauber nests. If installed, drill a 1/8 inch hole
in the bottom caps for moisture drainage. If they are not installed, increase the pipe
lengths accordingly. Cut the PVC pipe into four, three inch pieces, to make the feedpoint
isolators for each dipole.
One-half inch type L copper pipe has an actual OD of 5/8 inch and an ID of 0.545
inches. Copper pipe fittings now come in normal and pre-soldered5
varieties and the
dimensions can vary. It is more accurate to cut the pipe slightly longer than needed,
sweat the joint, and then trim to length with a tubing cutter and a file.
Centerline dimensions as well as cut pipe lengths (for pre-soldered fittings) are included
on Drawing 1. Use 6-32 x 7/8 inch stainless steel pan head screws, washers, and
locknuts for all feedpoint hardware. Drill the feedpoint screw holes using a drill press and
then deburr the inside of the pipe with a round file. Next, insert the three inch length of
PVC, align and tape the feedpoint assembly together, and then drill the PVC. This allows
the PVC to be easily removed for sweating the pipe joints and prevents it from melting.
Flag terminals are soldered to the coax and attached to the feedpoint screws. The
exposed coax ends are sealed with Coax-Seal6
and the harness is secured to the pipe
with cable ties. Male UHF connectors are soldered to the other ends of the coax.
Each 60 inch dipole section is secured to the mast with 10-24 x 1-¼ inch stainless steel
screws and stop nuts. After drilling 3/16 inch holes at each end (see Drawing 1), match
drill corresponding holes on the assembled mast sections. Insert a screw in each mast
from the inside and secure it on the outside with a stop nut. Depending on where the
mast holes fall this may require taping a string on the end of the screw and fishing it
through the mast hole. Each dipole can now be fastened to the mast by placing it over
the mast screws and secured with a stop nut.
Dimensional Changes
A larger diameter for the 60 inch vertical section is possible as long as the horizontal
distance between the vertical section OD and the dipole OD is maintained. The ½ inch
copper array centerline dimension between the vertical section and the dipole is 9
inches. This distance between outside diameters (for ½ inch copper pipe) is 8-3/8 inches
(9 inches between centerlines minus 5/16 inch on each pipe). If, for example, the 60 inch
vertical section is increased to 1-1/2 inches OD, you must maintain the 8-3/8 inches
between outside diameters. This will increase the centerline dimension to 9-7/16 inches.
The feedpoint dimension may also have to be moved slightly to obtain 50Ω at
resonance. An aluminum clamp-on array, shown on Drawing 4, illustrates the use of
different materials and construction techniques. The dipoles are made of 1-3/8 inch OD
aluminum tubing and are clamped to a metallic 1-1/2 inch OD mast. I encourage the
reader to use an antenna modeling program to model any changes before construction
Phasing Harness
The 4-element array phasing harness is based on feeding four 50Ω antennas from one
50Ω feedline. Likewise, the 2-element array uses two 50Ω antennas fed from one 50Ω
feedline. Coax connectors and tees are used to aid in a faster setup. If your antenna
installation is permanent, you may want to solder and weatherproof the coax junctions to
minimize losses. Figures 1 and 2 show the 4-element and 2-element harnesses,
respectively, with cable lengths and impedances at each point. Optimum coax lengths
are necessary to prevent from having too much cable to strap to the antenna. When
3. A 2-Meter Vertical Dipole Array, KG4JJH Page 3 of 6
cutting cable lengths, remember that the velocity factor applies only to that portion of
coax where the center conductor insulation is still in place. The math involved for
calculating coax impedance and length is as follows:
Lambda (λ) is the physical wavelength of coax and is defined as:
λ = (Electrical Wavelength at FO) X (Velocity Factor of the Coax)
Equation 1: ¼λ = (2952/FO) X (VF)
Where
FO = Design Frequency = SQRT (FINPUT X FOUTPUT)
For this TNSG7
repeater, the frequencies are
FINPUT = 143.225 MHz
FOUTPUT = 149.800 MHz
FO = SQRT (143.225 X 149.800) = 146.475, or 146.5 MHz
Equation 2: ZO = SQRT (ZIN X ZOUT)
Where
ZO = Transforming coax
ZIN = Input impedance
ZOUT = Output impedance
Each antenna is 50Ω at the operating frequency. Because we are combining four
antennas in parallel at the connection point, the impedance of the connecting cables A,
B, C, and D must be 100Ω at the point of connection. Two 100Ω impedances connected
in parallel produce an impedance of 50Ω. A quarter wavelength (and odd multiple) of
cable that provides the proper characteristic impedance can transform the 50Ω
impedance of each antenna to 100Ω at the connection point8
The required characteristic
impedance of cables A, B, C, and D can be found from the formula in Equation 2. In this
application, the calculation is shown as:
Cables A, B, C, and D:
ZO = SQRT (50 X 100) = 70.7, 75Ω coax
RG-11A/U, 75Ω, 0.66 VF (Wireman 121)
VF was verified using an MFJ-259B: 0.6638
Vertical distance between Dipole 1 - 2, and 3 - 4: 60 inches
Minimum length needed for each cable: 60/2 = 30 inches
Length needed for each cable (strapped to antenna): 29+8+3 = 40 inches
FO = 146.5 MHz
¼λ = (2952/FO) X (VF) = (2952/146.5) X (0.6638) = 13.376 inches
Odd multiples of ¼λ: 1 X ¼ λ = 13.376 inches (not long enough)
3 X ¼ λ = 40.128, or 40-1/8 inches
Cables E and F:
The math for cables E and F is the same except for the distances involved.
ZO = SQRT (50 X 100) = 70.7, 75Ω coax
RG-11A/U, 75Ω, 0.66 VF (Wireman 121)
Distance between Tees 1 and 2: 120 inches
Minimum length needed for each cable: 120/2 = 60 inches
FO = 146.5 MHz
4. A 2-Meter Vertical Dipole Array, KG4JJH Page 4 of 6
¼λ = (2952/FO) X (VF) = (2952/146.5) X (0.6638) = 13.376 inches
Odd multiples of ¼λ: 1 X ¼ λ = 13.376 inches (not long enough)
3 X ¼ λ = 40.128 inches (not long enough)
5 X ¼ λ = 66.880, or 66-7/8 inches
The phasing harness loss at 150 MHz is calculated to be 0.67 dB. Additional loss from
50 feet of RG-8 (Wireman CQ102) is 0.79 dB, for a total cable loss of 1.46 dB. The total
cable loss for the 2-element array is 0.96 dB.
Antenna Coverage and Testing
Initial testing was performed with the 2-element array in my back yard. Using a GPS,
latitude, longitude, and elevation data were fed into a HAAT9
calculator to obtain a value
of 33 feet. This “Height Above Average Terrain” value represents an average of the
terrain elevations within 10 miles of the transmitter site, and provides a single value on
which general coverage calculations and regulatory requirements may be based. Using
5 watts, comparisons with a J-Pole at the same elevation indicated that the 2-element
array was a major improvement for distant repeater access.
Subsequent testing was done with the assistance of NG4T, Communications and
Electronics Officer for the Third Alvin C. York Regiment of the Tennessee State Guard.
For this location, the 4-element array’s HAAT was calculated to be 40 feet. Antenna
coverage was tested using a Motorola Micor at 40 watts and a six cavity mobile
duplexer. Using 5 watt HT’s, communication ranges of up to 15 miles were established
in residential areas with rolling hills and considerable ground clutter.
Portability & Assembly
The array was built with portability in mind. Each 60 inch section mechanically attaches
to the next with a copper union and the array is clamped to a 44.5 foot fiberglass mast.
This sectional surplus mast was used by the military for camouflage screening. Stainless
steel screws (10-24 x 1-¼ inch and stop nuts) installed from inside the top 6 mast
sections secures the array to the mast. The array is offset about 10 inches down from
the top guy ring to prevent interference with the guy lines. The 4-element array weighs
13 pounds (including phasing harness) and breaks down into a 1 by 5 foot bag. A
second bag contains the harness, cable ties, Coax-Seal®, stakes, hammer, wrench, and
guy lines. A third bag holds the 12 fiberglass mast sections.
When assembling the array, ensure that all dipole feedpoints are oriented in the same
direction (i.e. all on the bottom or all on the top), and are lined up vertically. Failure to do
this will result in a less than optimal radiation pattern. I recommend labeling each dipole
and its associated position on the mast. Setup is accomplished with two to three people
in under two hours. Install a tilt base vertically in the ground at the desired location. Lay
the mast sections down with the large ends pointed toward the base and the screw
sections at the top. Plug the mast sections together, adding guy rings at the top of the
3rd
, 6th
, and 12th
mast sections. Attach each antenna section to the mast using 10-24
stainless steel stop nuts and connect the sections. Assemble the coax tee connections
and feedline and secure to the mast using cable ties. Waterproof the coax tee
connections using Coax Seal®. Next, attach the appropriate length guy lines to each guy
ring using snap clips. Measure a 23 foot radius from the base of the mast and install
three stakes, 120° apart, with one stake in the direction of the prevailing wind. Attach two
sets of three guy lines to the closer two stakes and pull/push the mast upright. Finally,
5. A 2-Meter Vertical Dipole Array, KG4JJH Page 5 of 6
secure the third set of guy lines to the last stake and adjust the guy line tension as
needed to obtain a vertical mast.
Antenna Gain Comparison
The EZNEC10
modeling program displays gain in dBi, whether in free space or over
ground. In an effort to present a fair comparison and to avoid confusion over gain
figures, several vertically polarized antennas were modeled and compared to the 2 and
4-Element Vertical Dipole Array. The reference antenna is a 2-meter vertical dipole
made of 5/8 inch OD copper, fed in the middle, and resonant at 146.5 MHz. The
modeled statistics for free space and 45 foot elevations (over average ground) are
summed up in Table 1.
Table 1
Elevation: Free Space Elevation: 45 ft.
2-Meter
Vertically Polarized
Antenna
Gain
dBi
Gain over
Vertical Dipole
dBi (dBd)
Vertical
Beamwidth
°
Gain
dBi
Gain over
Vertical Dipole
dBi
Vertical Dipole Reference 2.15 - 78.0 6.99 -
Collinear J-Pole 4.99 2.84 39.5 9.45 2.46
Vertical Moxon Rectangle 6.00 3.85 79.4 10.80 3.81
2-El Vertical Dipole Array 6.85 4.70 35.4 11.18 4.19
3-El Vertical Yagi 8.50 6.35 61.0 13.27 6.28
4-El Vertical Dipole Array 9.71 7.56 17.2 13.77 6.78
Transportable TNSG Repeater
With the recent addition of TEMA11
responsibilities to the state guard, regiments are
being asked to provide emergency communications during emergency and disaster
situations. To assist the Tennessee State Guard in accomplishing its mission, I have
donated this antenna and mast to the Third Alvin C. York Regiment for use as part of a
transportable Tennessee State Guard repeater system.
Wrapping Up
Elevation is the single most important factor when choosing a repeater antenna site and
it can be a challenging process to find the optimum location for a given target area.
Attempting this with a portable system is even harder as the location will change from
one setup to the next. The 2 and 4-Element Vertical Dipole Arrays presented here
provide some flexibility for installations in different situations. The 2-element array would
be the best choice for high elevation sites near the target area. The 4-element array
should be used for high elevation sites far away from the target area, or low elevations
sites near the target area. Portability combined with respectable gain has validated the 2
and 4-Element Vertical Dipole Array as an effective VHF antenna for emergency or
general 2-meter repeater use.
Allen Baker, KG4JJH
211 Brochardt Blvd.
Knoxville, TN 37934
865-675-1915
kg4jjh@arrl.net
6. A 2-Meter Vertical Dipole Array, KG4JJH Page 6 of 6
References
1
The general practice among commercial antenna manufacturers is to express gain in
dB (or dBd), where 2.15 dBi (Isotropic Gain) = 0 dBd (Dipole Gain).
2
Paul Shinn, KAF8333, What They Never Told You About Repeater Antennas, GMRS
Web Magazine; http://www.popularwireless.com/gmrsrpt051599.html
3
A 7 dBi omni version is possible, but the elevation pattern is somewhat distorted.
4
L.B. Cebik, W4RNL, E-mail correspondence.
5
EZ-Sweat™ pre-soldered copper fittings, Watts Water Technologies;
http://www.wattsreg.com/pro/whatsnew/whatsnew_ezsweat.htm
6
Coax-Seal, http://www.coaxseal.com/
7
The Amateur 2-meter band plan is 144-148 MHz. 143-150 MHz is for a Tennessee
State Guard (TNSG) repeater; http://tsg3.us
8
Harold Kinley, Antenna Phasing 101, Mobile Radio Technology, September 1, 2004;
http://www.findarticles.com/p/articles/mi_m0HEP/is_9_22/ai_n6196620
9
Stan Horzepa, WA1LOU, The Return of the HAAT Calculator, ARRL Web, January 6,
2006, http://www.arrl.org/news/features/2006/01/06/1/
10
EZNEC Antenna Software, Roy Lewallen, W7EL; http://www.eznec.com/
11
TEMA, Tennessee Emergency Management Agency
7. A 2-Meter Vertical Dipole Array, KG4JJH Attachment 1 of 9
Figure 1
4-Element Array Phasing Harness
Impedances are shown in red and cable lengths in blue.
Figure 2
2-Element Array Phasing Harness
Impedances are shown in red and cable lengths in blue.
3
1
260"
50 OHM COAX
TO TRANSCEIVER
60" 120"
ANTENNA-2
ANTENNA-3
ANTENNA-4
COAX
TEE
COAX
TEE
COAX
TEE
100
100
50
50
50
ANTENNA-1
50
50
50
50
A = 40-1/8"
B = 40-1/8"
C = 40-1/8"
D = 40-1/8"
100
100
100
100
E = 66-7/8"
F = 66-7/8"
60"
60" 50 OHM COAX
TO TRANSCEIVER
ANTENNA-2
COAX
TEE
100
50
ANTENNA-1
50
50
A = 40-1/8"
B = 40-1/8"
1
100
8. A 2-Meter Vertical Dipole Array, KG4JJH Attachment 2 of 9
EZNEC SWR Plots for Individual Dipoles in the 4-Element Array
Dipole-1
Dipole-2
Dipole-3
Dipole-4
9. A 2-Meter Vertical Dipole Array, KG4JJH Attachment 3 of 9
EZNEC Plots for Free Space
4-Element Vertical Dipole Array
2-Element Vertical Dipole Array