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Questions tagged [antenna-construction]

Materials and methods for building antennas, and design of supporting (non-conductive) structures. For design of antennas themselves, use [antenna-theory] instead.

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20 votes
2 answers
15k views

How to detect common-mode currents or “RF in the shack”?

Let's say we already know that if your antenna is not suitably constructed or connected then you can get current on the shield of your coaxial feed line which will flow through the shielding/grounding ...
Kevin Reid AG6YO's user avatar
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36 votes
4 answers
57k views

Effect of different metals for antenna elements

Other than rust, corrosion, and other reactions with air that would make the use of a metal unfavorable, how do different metals affect the performance? Let's give Yagi an example: Let's say I use 4 ...
Skyler 440's user avatar
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3 votes
3 answers
5k views

What happens to a vertical Yagi when you mount it on a vertical metal pole?

How much difference does a metal pole make when it's sitting in the middle of all the lower elements of my beautiful new highly optimized to the max YO.EXE 10 m yagi ? I get it that the closeness of ...
Andrew's user avatar
  • 3,723
7 votes
2 answers
2k views

Dipole Antenna Current Distribution at any Time Instant

Above is a connection of half-wave dipole antenna. The book states that the current profile is same at any given time instant on both the radiators, each of quarter wavelength length. Now my ...
user3001408's user avatar
21 votes
5 answers
78k views

Good wire for wire antenna?

What properties should I look for in a good wire for building a wire antenna? Could anyone recommend something specific for me?
Timtech's user avatar
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11 votes
1 answer
3k views

How to combine two 50 Ω antennas such that they appear as one 50 Ω load?

I'm looking for a simple way to impedance match an array of two 50 Ω antennas so that when they are combined they appear as one 50 Ω load. Assume that both antennas are identically constructed, are ...
Ben's user avatar
  • 347
7 votes
8 answers
13k views

How does the length of a metal sleeve around a (shieled) coax cable affect antenna performance?

A post on http://adsbexchange.com/forums/topic/beginners-2-cantenna-easy-diy-antenna-to-improve-rangeplane-count uses a $\frac{\lambda}{4}$ sleeve made of a pop can beneath a $\frac{\lambda}{4}$ wire ...
Jonathan's user avatar
6 votes
1 answer
8k views

Noise bridge use in antenna construction?

How does a noise bridge work? And how can a noise bridge be useful in building, testing, and/or tuning an antenna?
hotpaw2's user avatar
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6 votes
3 answers
10k views

What is the velocity factor of a wire?

This is Belden 9223. It is a 50-ohm coaxial cable, velocity factor 0.56 This is Belden 8524. It is a 22 AWG hookup wire. No velocity factor in the datasheet. Why does the coax datasheet have a ...
Phil Frost - W8II's user avatar
5 votes
1 answer
699 views

Dipole Center Spacing

I have a question about dipole construction. I am working with a turnstile, but building dipoles to validate my system with linearly polarized transmission before moving on to circular. My design has ...
Kontakt's user avatar
  • 155
3 votes
2 answers
1k views

How to make a "you're getting warm/cold"/"fox hunting" game based on RF signals

I would like to build a system in which the emitter emits omnidirectional RF signals, and the receiver gets a stronger signal (it does not have to be accurate) with a) closer distance from the emitter ...
user42875's user avatar
  • 151
1 vote
4 answers
166 views

Which 10 m antenna will give the most rejection in one direction for received signals which are vertically polarized?

I want to null out a particular direction so that i can't receive some vertically polarized interference on 10 m coming from that direction. Which 10 m antenna will give the most rejection in one ...
Andrew's user avatar
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23 votes
3 answers
4k views

Can I build a radio telescope out of a parabolic TV satellite dish?

I have the possibility to buy a very inexpensive 2.4m parabolic satellite dish and I would like to build a radio telescope from it. Originally this dish was designed to be a satellite TV antenna. ...
SP5RFD's user avatar
  • 333
12 votes
4 answers
6k views

Capacitive hats on wire dipoles?

Capacitive hats seem to be advertised as an option for mobile vertical antennas. One mentioned advantage is the they can widen the SWR bandwidth, making the antenna easier to tune. What might be the ...
hotpaw2's user avatar
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9 votes
3 answers
3k views

RigExpert AA-35 - Interpreting The Information

I have a new RigExpert AA-35 antenna analyzer. 1st one I have had & 1st time trying to use an analyzer on an antenna. My questions are very basic and general, but I am having difficulty in ...
B. Varner's user avatar
  • 149
9 votes
2 answers
4k views

What is the largest gauge (thinnest diametre) wire I may use as an antenna?

A follow-up to Good wire for wire antenna? I'm QRT at present - thanks to fooling around with just a couple of diodes and PVC capacitors instead of a well-regulated supply. The antenna I used earlier ...
VU2NHW's user avatar
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8 votes
3 answers
2k views

Will anodizing or powder coating or wetcoating (painting) antenna elements affect performance?

I want to put up a small tower and beam on my roof, but I don’t want the aluminum to “stick out” and want it to be unnoticeable as possible. I would think black anodizing would be the best solution ...
NT1K's user avatar
  • 81
7 votes
4 answers
4k views

Antenna options for a 10x20m property with a large metal roof?

I live in a house that sits in the middle of the city, in a lot 10x20m in size. The first 6x10m are covered by a metal roof with a rather low angle (IIRC only 50cm difference between the highest and ...
hjf's user avatar
  • 1,219
7 votes
7 answers
10k views

What is the attraction of vertical antennas for HF?

I understand that MW broadcast stations use vertical antennas because that polarization works much better for groundwave propagation. But in amateur radio, I would assume the focus for communications ...
natevw - AF7TB's user avatar
6 votes
2 answers
6k views

Is copper-clad steel a good material for wire antennas?

There are some people selling steel wire plated with copper for making wire antennas. Perhaps the most well-known brand of this product, Copperweld, makes at least two kinds of copper-clad wire, ...
Phil Frost - W8II's user avatar
6 votes
2 answers
160 views

How is phone cable with iron called?

In in Russia I saw a phone cable called "field cable" (провод полевой П-274-М). It is a loosely twisted pair with some iron strains added alongside with copper ones. I tried to lookup ...
k1zmt's user avatar
  • 337
6 votes
3 answers
4k views

antenna in the rain

What kind of changes can be expected in the behavior (resonance, SWR, etc.) of a mobile vertical HF antenna between dry conditions and wet rainy weather? (assume a coax feed-line and low SWR in dry ...
hotpaw2's user avatar
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5 votes
5 answers
3k views

Loop antenna layout and radiation?

I've got, for the near term, limited resources to put up an HF antenna at my home. One of the options I can manage without excessive cost is a loop, which would enclose the house. I need to transmit ...
Zeiss Ikon's user avatar
  • 4,147
5 votes
1 answer
470 views

Will stainless steel bolts work with my copper antenna?

My antenna is copper, elements and the beam. I would like to bolt them together where they cross. Would stainless bolts work? Just sweating them together lets them twist and move some in high winds.
arkieguide's user avatar
5 votes
1 answer
2k views

Connect Printed Yagi-Uda Dipole Array with Balun to coaxial cable correctly

I am making the Printed Yagi-Uda Dipole Array with Balun (that is the full name). I used Antenna Magus to calculate dimensions. I am not sure how to properly connect it to coaxial cable. Here is what ...
Triak's user avatar
  • 153
5 votes
2 answers
3k views

Dipole antennas: Will paracord hold up well enough in the sun? Is there a better alternative?

Tower is up and pre-stretched multi-strand 14 Ga wires are cut & terminated for a multiband fan-style dipole antenna system. Location is the desert southwest of the USA. Stringing up parts of it ...
SDsolar's user avatar
  • 2,087
4 votes
2 answers
441 views

DIY Short Vertical Wire Loaded Antenna: Using 20 Ohm Resister to Widen Q

I've been working with Xnec2c to model a 40 meter vertical antenna I want to build for field QRP. This antenna is short at 25 feet and uses a 1:1 unun at the base with 4 radials. The model has the ...
wbg's user avatar
  • 301
4 votes
1 answer
7k views

3 Band (80-40-20 Meter) Fan Dipole Tuning Question

I built a fan dipole according to the basic instructions in the SRI publication describing the theory and basic design. My questions is about next steps in tuning for the various bands. I am ...
Hogstrom's user avatar
  • 187
4 votes
5 answers
6k views

Significance of 1/4 wavelength with respect to antennas

I am a new to the radio design field. My question is, 'What is so significant about 1/4 wavelength with respect to antennas.' From the information I have gathered from various sources, it is my ...
Newbie's user avatar
  • 181
3 votes
1 answer
391 views

UHF cubical quad VNA analysis interpretation

I've designed a two element UHF cubical quad. It was designed to resonate at 385 Mhz. I used 0.1mm thick and 1cm wide copper tape instead of wire to lower the antenna Q. I used PVC electrical conduit ...
rodv92's user avatar
  • 173
3 votes
3 answers
6k views

How do I construct the driven element of a yagi?

I've been poking around the internet on how to make a Yagi for my HT. I understand all the math for cutting directors and reflectors to length and placing them at the correct spacing for 146.52 mHz. ...
user6099's user avatar
3 votes
1 answer
824 views

Understanding of NFC Reader Antenna matching

I have been designing a 20 x 20 cm square NFC reader antenna which looks like this: In order to make it work and detect NFC tags at certain distance, it needs to be matched. To do that I was trying ...
Vlad Ekaterinichev's user avatar
3 votes
3 answers
1k views

Unexpected Resonance - Dual-Band Dipole

I tried to make a dual-band (2m/70cm) dipole this morning by following the instructions on this page: http://www.amateurradio.bz/2m-70cm_vertical_dipole_antenna.html, with the rather major significant ...
William's user avatar
  • 813
2 votes
0 answers
144 views

Biconical antennas - bandwidth and installation

I am posting this question (and its related question) here because of the unique expertise that Ham Radio Operators have as it relates to antennas. I'm a newish Ham and really appreciate your help ...
FontFamily's user avatar
2 votes
3 answers
416 views

Constructing a ground level antenna array to monitor radio frequencies using SDR

New to this community and also a newish Ham. Hello everyone. This question could easily have been posted under 'Astronomy', but I thought I would start here since Hams tend to be quite knowledgeable ...
FontFamily's user avatar
2 votes
5 answers
2k views

Metal for antenna construction?

What do I need to consider when choosing metal for an antenna? How do I determine what thickness to use?
Timtech's user avatar
  • 2,336
1 vote
2 answers
536 views

Antenna Size limits at 2-30 MHz (10 m to 150 m wavelength)

I am interested to know what are the smallest antenna sizes that are efficient transmitters for skywave propagation/ham radio applications. Has anyone been able to design a transmit antenna to work in ...
AmateurRadioFan's user avatar
1 vote
2 answers
3k views

How to best connect an FM transmitting GPIO pin to an antenna?

I'm trying to use a RaspberryPi3 as a FM transmitter, using pifm and/or PiFmRds to send audio in 88-108 MHz band. The RPi can then use the GPIO-4 pin to transmit between ...
not2qubit's user avatar
  • 378
1 vote
1 answer
86 views

Effect of small amount of metal on twin-lead

I have a G5RV Jr. antenna on a fiberglass mast at 10m height. The only metal on the mast is a 1/8" thick steel guy ring with stainless steel snap links, plus a few small metal screws. Hanging freely,...
K8KV's user avatar
  • 377
0 votes
1 answer
527 views

LTE (4G) - Is two (or multiple) antennas better than one?

I have two antennas. A "multiband" (1710~2170 Mhz, 22 dBi)... ...and a "fullband" (700~2600 MHz, 15dBi)... Taking into account that my modem (router) is "fullband" and ...
Eduardo Lucio's user avatar
0 votes
0 answers
78 views

LTE (4G) - Which external/outdoor antenna type is the best?

I've seen several antenna types out there, but I can't know for sure which model is the best for external/outdoor LTE (4G) use. I have to say that I don't understand anything about LTE (4G) antennas......
Eduardo Lucio's user avatar
0 votes
3 answers
736 views

How can a vertical Yagi for 10 m be mounted on on a vertical metal mast and be made to work properly? [duplicate]

From a reply to a previous post I've been told that a horizontal tube half a wavelength long mounted right at the junction between the boom on a vertically mounted yagi and a vertical metal pole will ...
Andrew's user avatar
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