Questions tagged [antenna-system]

The system composed of an antenna and a feed line, and possibly also an RF ground connection, antenna tuner, balun, phasing device, et cetera.

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1answer
68 views

How did SMA connector size become standard?

I'm working on a project in microfluidics and it has become apparent that a significant challenge to overcome is a lack of consensus in connector design. I have been thinking about my time working ...
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2answers
65 views

horizontal EFHW antenna attached to gutter

I'm brainstorming methods of mounting an EFHW. Unfortunately, I have no trees, so I'm considering a horizontal gutter mount which would afford me about 70 feet. Is this workable or should I consider a ...
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51 views

Is there an instance where you can directly feed a half wave dipole with coaxial cable without having to worry about balanced to unbalance?

Like the question says, can you feed a dipole with coax with no ill effects? Nothing else in the system, just the antenna and the cable.
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29 views

J Pole, what is the best way to deal with Common Mode Current? [duplicate]

I am planning on utilising a ferrite choke on a J Pole antenna for CMC. Placement directly on the feedpoint poses possible mechanical restraints. Is it okay to place it a quarter wave down the coaxial ...
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1answer
44 views

What lengths of coaxial feed lines should you avoid?

Are there lengths of feed line to avoid or ones that may cause problems with an antenna system? For single band use. Appendix: The run of coaxial will be for the 10 metre band. I would imagine this ...
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30 views

How lossy are gamma matches?

What are the real losses associated with a typical gamma match at a set frequency? Furthermore, are there good designs or dimensions to minimise these losses?
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3answers
90 views

Why is outer coax usually grounded?

I'm building a simple ground plane antenna for VHF, and I'm doing some research on grounding in case I want to permanently install it. I keep hearing that the ground rod is connected to the outer coax ...
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1answer
30 views

How to calculate of shielded loop antenna correction factor without extra antenna measurements

A lot of article about 60 cm shielded loop antennas and how to measure antenna factor using antennas with already known antenna factor. But for example if I have one shielded loop antenna (...
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2answers
79 views

How many turns of wire inside 60 cm shielded loop antenna (9kHz - 30 MHz). How can I find this number without destroying the antenna?

Lots of information about shielded loop antennas is available on the internet. However, antenna manufacturers do not indicate the number of turns. How can I find the number of turns of a manufactured ...
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1answer
47 views

60cm 9 kHz 30 MHz Shielded loop antenna behavior as a transmitting antenna

I know how shielded loop antenna work as a receiver antenna. (How behave electric and magnetic field). But I can not understand how shielded loop antenna works as a transmitter. Will it produce only ...
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1answer
64 views

Looking for criticisms on my VNA-like SWR meter I am designing

I am in the process of building a SWR meter with VNA-like features. I'd be really interested to hear from fellow hams any input, suggestions, or tips they have regarding this before I go get it mass ...
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116 views

DIY Triplexer for HF (low), 6m (med), and 2m/440 (high)

I'm looking at picking up the TYT TH-9800, which is a Quad-Band FM radio on 10m/6m/2m and 440 (I'm lucky enough to have some 6m and 10m repeaters in the area). I know there exists quad band antennas ...
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1answer
131 views

Should I bother with a doublet if I can't go straight to the tuner with open wire?

I have two trees about 135 feet apart and about 55 to 65 feet tall. I have been trying to determine which kind of wire antenna to put up there. Initially I was considering either a fan dipole or ...
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2answers
72 views

Relative disadvantages of impedance mismatch vs. non-resonant length wire antenna

So given a choice between a non-resonant length of wire antenna center fed by 50 Ohm coax, or a resonant length of wire fed highly off-center by 50 Ohm coax, or a resonant length of wire fed by high ...
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1answer
70 views

impedance matching with window twinlead

Question from new ham here, regarding ways of matching impedances between a feedline and an antenna. Is it possible to fashion a broadband HF impedance matcher from a length of windowed twinlead, in ...
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4answers
376 views

Any reason not to choose a discone antenna over a Wide/ MultiBand mobile antenna for TX/RX operations

We are setting up a all-band radio in an emergency com center that's intended most for amateur band use, but since its' for emergency use will also be used in the public safety bands; (150-170)MHz, (...
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121 views

Antenna Basics - Open/Short Circuit & Half-Duplex/Full-Duplex

I am beginner in the Antenna theory and I have a few basic questions. Please help me to clarify my understandings related to the basics which I have read. And this question has 3 basic questions. ...
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1answer
54 views

What Are Some of the Most Important Characteristics Applying to the Radiation of Monopole Antenna Systems?

Such characteristics are described in Answer 1 below, as sourced in a study of antenna engineering textbooks, and by generating NEC4.2 studies.
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4answers
144 views

Why do we talk about common mode current from an antenna, but not from a transmitter?

There's a lot of information available about how to block common mode current originating at the antenna end of a coax cable. But, I haven't seen any reference to common mode current originating at ...
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1answer
50 views

Vertical Hustler - do I need any radials?

I'm planning on installing a Hustler 4-BTV vertical by the house. There's already a 12 ft. steel pole mounted in cement, so I'm going to mount it on that pole about 10 feet up (sort of small mini ...
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1answer
80 views

How should I stack these folded dipoles?

Looking to stack these 8 folded dipoles on my 100ft tower. I can not find any information whatsoever on these. I have 4 consecutive serial numbered boxes. Bluewave Marathon BME139FN1H0 138 - ...
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3answers
587 views

Ideal Doublet Size 160-10 Meters

Is there considered an ideal / optimum length for a doublet for use on 160-10 meters when fed with open-wire feedline and a balanced tuner in the shack?
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1answer
40 views

How can I design a microstrip patch rectenna that can power up 1W of payload?

I know the major components of rectenna should be Receiving antenna - Patch Antenna Matching circuit Low pass filter Rectifier - Schottky diode but I could not visualize how can we put all ...
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2answers
254 views

Actual Impedance of a folded dipole at resonance

I am using a Folded Dipole which I bought when I first got my General License. It was advertised as an all band antenna. My results with it were less than the claims made by the makers to say the ...
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2answers
94 views

Does RF go through thin corrosion better than DC?

I might have a bit of a problem with my groundplane, but I am unsure. I am using a ground screen instead of radials. The problem is the ground screen is made of galvanized metal, but I can see that a ...
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115 views

ISOTRON 80m 75m Antenna Position

I know, a dipole is the way to go, but cannot fit one, only a 'birdhouse' antenna like the 75m 80m Isotron antenna. Is it better to put at 15 feet Above Ground Level outside, or 20 feet AGL ...
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2answers
86 views

Using two VHF antennas vs one because of a large obstruction

We have a VHF Omni directional antenna, 2.5 W and 119 MHZ (approximate) mounted on top of a commercial hanger. Access to the antenna is out of the question because of the lack of fall protection. ...
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6answers
546 views

How to match low impedance of NVIS Dipole?

I want to match a 50-ohm coax feed wire to a 40-meter NVIS half-wave dipole. NVIS antenna examples I've found are usually based on a regular dipole (72 ohms in free air). However the impedance drops ...
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1answer
155 views

Counterpoise wire voltages?

One practice which seems common when operating temporary or portable QRP, SOTA, etc., is to throw a counterpoise wire out on the park lawn or shrubbery, mountaintop or hillside or parking lot ground, ...
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2answers
83 views

Grounding of a portable setup

I am occasionally using an extremely simple shortwave portable setup consisting of a battery, the transceiver, a short coax feedline and a vertical half-wavelength vertical antenna with a transforming ...
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3answers
287 views

How does the Maximum Power Transfer Theorem relate to RF power amplifiers?

The Maximum Power Transfer Theorem says that maximum power transfer occurs when the source impedance equals the load impedance, when the power transferred to the load is 50%, the other 50% being ...
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1answer
194 views

How does a higher antenna reduce rain static on a lower antenna?

I have operated at several stations - including my own - where a 40m beam is stacked above a tribander. During a rain storm, there is so much QRN on the 40m beam that the band is unusable, but the ...
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1answer
79 views

How to simulate two antennas in 4nec2

I need to simulate 2 helix antennae placed side by side, and see the resultant radiation pattern. But after adding the second antenna with a separate and when I try to simulate 4nec2, only simulated ...
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1answer
46 views

Antenna system components in the rain

An antenna system often consists of more than the feedline and radiating wires: such as fixed or tapped loading coils, LC traps, baluns, toroids, air variable capacitors, roller inductors, feed horns, ...
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1answer
87 views

Is this antenna “system” really work? [closed]

I posted yesterday asking how can I have signal inside my house which my house is obstructed by a hill from direct signal from the cellular's operator' Base Transceiver System (BTS). The schema of the ...
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2answers
696 views

Understanding RG6-75 ohm Cable Impedance

Here is my measurement to a piece of RG6 cable. It is around 30cm cable. On the shield is written COAXIAL CABLE 5C-2V 75 ohm. From my measurement I got data as below: From that table, we can see that ...
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4answers
572 views

What is the maximum and minimum of antenna gap of dipole antenna?

Consider the picture below is design of half wave length (λ) dipole antenna. I read some explanations saying that it is the best design to get the optimum transmit power. Half wave length (λ) is from ...
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1answer
101 views

What happens when you directly couple the transmitter antenna to the receiver antenna?

I was wondering what happens when you directly electrically couple the transmitter antenna to the receiver antenna? Particularly I’d like to know what happens for FM radio broadcast. Since I don’t ...
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3answers
476 views

Why have knife switch storm grounds for antennas vanished?

Long ago, it was fairly standard to provide lightning protection for outdoor radio antennas by installing a large double-throw knife switch -- antenna leads to the center, radio on one side, ground on ...
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3answers
818 views

VHF 50 Ω Antenna Over 75 Ω TV Coax

I have a 50 Ω VHF airband antenna which I’m planning to install in my loft, for use with a RaspberryPi-based RTLSDR scanner/receiver. I already have a UK-standard UHF/Freeview antenna using standard ...
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3answers
4k views

Using 75 Ω instead of 50 Ω coax feed

Can I replace my old 50 Ω coax with RG6? It's cheaper and less loss at VHF/UHF. I would match by L/2 multiples of coax to repeat input and output impedance or L/C matching networks at each end. Is ...
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240 views

Passively reducing ground loss?

Would a disconnected wire or conductive mat below a low height antenna reduce ground losses? A tuned length of wire under a wire antenna might be suitable for NVIS gain. But would a bunch of space ...
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7answers
768 views

Is it practical to use a slug-tuned variable inductor in an antenna matcher (aka “antenna tuner”)?

I will soon need an antenna impedance match (aka "antenna tuner"), because I'll initially only have a single antenna for my HF rig (needs to cover 80m, 40m, 20m, 15m, and 10m). Obviously, in order to ...
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1answer
199 views

Is it safe to run two barefoot rigs on one antenna with an AB switch?

I have a Daiwa CS-201A two position switch. The single side is connected to by quarter wave vertical (40m). The A and B sides are connected to an IC-7300 and TS-830S. The switch is claimed to have ...
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2answers
677 views

Bow Tie antennas impedance

I see on the internet that a radio amateur made bowtie antennas for transmitting and receiving on the 2 meter and 10 meter bands. They produced very good SWR bandwidth when fed with 50-$\Omega$ coax. ...
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1answer
143 views

Why does adding 50-ohm BNC Ethernet terminator(s) in parallel to my 4-element yagi improve my radio's reception? (70cm)

I have this radio, with a rubber duck antenna, and a repeater twenty miles away to my north-northwest. If I set my radio on the top of a cabinet in my bathroom, I receive the repeater fine. I can't ...
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323 views

What additional information do I get from an RF ammeter, as compared to a regular SWR/wattmeter?

I've grown up using SWR/power meters. They're "simple" devices: They show forward and reverse power, and show the standing wave ratio. They, however, do not show antenna efficiency. New hams are ...
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2answers
367 views

Share wide band antenna with multiple transceivers

I'm trying to incorporate several transceivers on my board design; I need WiFi (2.4 GHz) SatCom (~1.6 GHz) RF (~900 MHz) and GNSS (~1.5 GHz). I need to combine them into one antenna. I found a wide ...
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1answer
87 views

How to model passive elements when simulating an antenna?

So I started writing an antenna simulator program to design antennas for my needs. To calculate the electric field vector at every point, I split the active element of the antenna into a large number ...
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3answers
180 views

Output power curve of an antenna

My approach is that a radio wave is made from zillion of accelerated electrons which emit zillions of photons. Since the current flows in a open circuit, the antenna generator works against something ...