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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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36 votes
4 answers
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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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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
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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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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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15 votes
1 answer
9k views

What is the purpose of a balun and a unun in a feed line?

I have never understood how a balun or a unun works and under which situation I need to use either of them in an antenna feed line.
Dinesh Cyanam's user avatar
13 votes
5 answers
11k views

Is an antenna analyzer necessary for building antennas?

I'd like to try my hand at building a few antennas for VHF/UHF use. I'm going to be going approximately from established designs, but obviously the final result will require some tuning. I don't ...
David KF4MDV's user avatar
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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12 votes
3 answers
14k views

Protect rig from static charge on antenna

How can I continuously discharge static from my end-fed antenna? My Electraft K2/100's autotuner (schematics) has an SWR bridge using two 1N5711 pin diodes. These diodes get blown if any static ...
Wayne Conrad KF7QGA's user avatar
11 votes
6 answers
17k views

Can you use a satellite dish for a ham radio antenna?

Can I use a satellite dish as a ham radio antenna? I was thinking that because there are two unused, working satellite dishes that have all appropriate wires attached conveniently to the roof of my ...
hopefulhacker-Reinstate Monica's user avatar
11 votes
2 answers
771 views

How to determine if my antenna is an effective radiator?

So I build an antenna, tune it with the SWR and make it look great for a 50 ohm load. That does not determine if it is good at getting a signal out or not, it could just be a 50 ohm dummy load. ...
Skyler 440'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
10 votes
1 answer
1k views

Can I have multiple inverted-vee antenna fed by a single coax?

A friend who recently received his call is planning to setup an inverted-vee for 40/20m bands. Our take is the signal will take the path of least impedance into the correct length antenna wire. ...
VU2NHW's user avatar
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10 votes
1 answer
7k views

How to design a rubber ducky antenna

I am attempting to design an antenna for a 162.4 MHz omni receive only application and am confident it is going to be difficult if not impossible. I have very tight specs on space(6" diameter by 3" ...
Josh Cox's user avatar
  • 241
9 votes
6 answers
17k views

Aluminum vs copper antenna element lengths

Does the particular metal used in antenna elements make any difference in element length or spacing, i.e. 1/2" aluminum tube vs 1/2" copper tube? I know that length and diameter have an effect on ...
David Thorpe's user avatar
9 votes
4 answers
1k views

Why are there differences in antennas that depend on electrical component and magnetic component of a radio wave?

I understand the idea that when we are targeting the electrical component of the radio waves we need to have some form of a linear conductor that receives the electrical component, this creates a ...
Bartha's user avatar
  • 169
9 votes
3 answers
24k views

How would I modify a satellite dish to transmit and/or receive to a Baofeng UV-5r plus? ( A handheld transceiver) If it's possible

I have an old satellite dish just lying around and was wondering how to hook it up to my baofeng uv-5r plus.
Sudo_Cats's user avatar
9 votes
5 answers
5k views

Wire antenna slightly too long

Say I have a wire antenna that is slightly (a few percent) too long for the desired frequency (of resonance or lowest SWR). What are the options, other than cutting the wire(s) and very likely ending ...
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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9 votes
2 answers
455 views

Is steel or aluminum structurally a better material for catenaries?

I understand that steel is not a good material for antenna wire, but let's consider that I'm using the wire for purely structural support, or I am cladding it with copper to address the RF ...
Phil Frost - W8II's user avatar
8 votes
3 answers
405 views

Wider wire = picks up more energy, yah?

I have seen many discussions re: wire gauge, insulation, velocity factor and K-factor...unfortunately, statements from various sources are not always in agreement, but that is not the issue. The issue ...
Mein Tenah's user avatar
8 votes
1 answer
1k views

Do I need a SWR meter for a basic 2 meter antenna?

I have a 5 watt 2 meter handheld transceiver and want to build a helmet with an antenna, microphone (with VOX enabled) and earpiece for the radio. For the antenna part, I just want to do something ...
Skyler 440's user avatar
  • 7,620
8 votes
2 answers
2k views

cubesat turnstile antenna material selection

My cubesat team is working on our design for rolled whip antennas to deploy in a UHF turnstile configuration based on this design: What I would like advice on is the material for the antennas ...
Kontakt's user avatar
  • 155
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
8 votes
3 answers
1k views

Can I use a helical ground plane radial in the same way that a loading coil works?

I'm working out the science behind mounting an antenna on a vehicle, and I came across the concept of ground planes. This answer says that longer is better but don't worry about it too much, but this ...
YetAnotherRandomUser's user avatar
8 votes
1 answer
5k views

What's an appropriate core material for a loopstick antenna?

A loopstick antenna, if you don't know, is a coil of many turns around a high permeability core. They are frequently encountered in AM receivers and look like this: This particular example is ...
Phil Frost - W8II's user avatar
8 votes
2 answers
976 views

Simulating two antennas (transmitter and receiver) using 4nec2 tool

I am trying to find near field mutual coupling affects between two antennas - one being transmitter and other being receiver. The receing antenna is fed with very little voltage (I think, if I don't ...
Shiva Mudide's user avatar
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
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
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
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
4 answers
655 views

If I tie antenna wire in a knot, will there be damage to the wire?

I'm building HF kits 80m EFHW kit, and in the instructions it directs you to tie a knot in the antenna wire. I'm concerned of damage to the wire. I have found no source as of yet that indicates if ...
Erik Rusell's user avatar
7 votes
1 answer
580 views

Antenna for receiving 868MHz rocket telemetry: QFH(QHA), Helical, or?

I'm building a radio communication system for an amateur rocket project. We've decided to use LoRa 868MHz system. My question is, which antenna for the ground station will be the best choice? We're ...
leller's user avatar
  • 181
7 votes
1 answer
1k views

How to make a ferrite bar antenna for RTL-SDR?

I bought a RTL-SDR (blue one with little MCX antenna). I modified its Q branch, and can receive short wave radio with Degen 31MS antenna now. For MW, Degen 31MS antenna has a ferrite bar antenna ...
jac123's user avatar
  • 73
7 votes
1 answer
1k views

How does aluminum siding on a house affect an inverted-vee antenna next to it?

My two-storey house is wood with alumninum siding. I had wanted to install an inverted-vee antenna with its midpoint hanging from the eave, and endpoints near the ground, but this would place the ...
Cyberherbalist's user avatar
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
  • 13.5k
6 votes
2 answers
5k views

Tuning/trimming a ground plane antenna

I've built a ground plane antenna with a 19.5" vertical and 4 20" radials. Currently, at 147.135 MHz my SWR is 3:1, clearly not ideal (and even bad for the transmitter!). I'm reluctant to start ...
David Hoelzer's user avatar
  • 1,052
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
6 votes
3 answers
2k views

Does an End-Fed Antenna need to be straight?

Typical yard and wondering if I can go out a window, to a tree, turn to another tree, turn to another tree simply trying to achieve the length required for 80m band? One video stated it doesn't need ...
Mot's user avatar
  • 61
6 votes
3 answers
938 views

Is a boom important to a Yagi?

I am trying to make a yagi for a 900M. The tinkering starts causally with some 1.2mm welding wire (cut to size based on K7MEM yagi calculator, direct soldering, no special matching as suggested on ...
Ben's user avatar
  • 163
6 votes
5 answers
2k views

How important is the impedance and resonance of a receive antenna?

I'm very new to shortwave radio, as evidenced here: Can an antenna be too powerful for certain receivers? I want to build a longwire receive-only antenna for the HF frequencies. I've been using ...
fishfritters's user avatar
6 votes
2 answers
1k views

Why don't J-Poles need to be grounded?

I'm building my first J-Pole and the different projects and articles I read about differ slightly but one commonility is a J-Pole does not need to be grounded. Why is that? I read that it is optional ...
john_ham_radio's user avatar
6 votes
4 answers
879 views

Weather-proofing antenna connections

Here's a problem: you buy a fancy new vertical for a fair bit of coin, but there's no coax connector on the thing. There are just screw terminals. You need to attach coax to it, but in such a way ...
Phil Frost - W8II'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
4 answers
8k views

Does oxidation of the antenna elements have any impact on the signal quality of the station?

So I'm still QRT; apart from a brown-out on the rig, the support on the inverted-vee toppled over in high winds. Thanks to the topple-over I discovered the conductors (SWG 16 bare copper) had ...
VU2NHW's user avatar
  • 2,834
6 votes
3 answers
256 views

Antenna options

I am considering a new ham station in a relatively urban environment on the South coast of England, and would like like some ideas / feedback on antenna options. Aim is to get reasonable performance ...
Oliver Schönrock'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
  • 13.5k
6 votes
3 answers
384 views

Will an iron chimney work well as an antenna?

There is an iron chimney near my house that is not used anymore. It is ~15 meters in length and ~0.5 meter in diameter. How good will it be as an antenna for rtl-sdr?
vasili111's user avatar
  • 163
6 votes
4 answers
5k views

Can an HF antenna be put inside a tree?

There are some trees around with branchy tops that seem wider than half of 10M, maybe even half of 20M, and above the nearby rooftops. Can a wire dipole or a vertical be mounted inside a tree? If so,...
hotpaw2's user avatar
  • 13.5k
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
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