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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4
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3answers
692 views

Suggestions for mounting a mini-whip as high as possible

I've ordered two mini whip antennas from Ebay (Russia) for HF and MW. As power lines cross my city property in a L shape - the only way to get away from them is to go up. So I'm hoping that going 5-...
5
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2answers
801 views

How to adapt commercial VHF yagi for 2 meter amateur use?

I recently acquired a Decibel 3-element VHF Yagi that was formerly in commercial service. I connected my MFJ-259B antenna analyzer to the antenna and found its minimum SWR at 155 MHz. I have not ...
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1answer
102 views

Resistance of antenna dipoles

A quick question: Is it a disaster if the two legs of a v-dipole antenna are different resistances? Thanks.
3
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2answers
417 views

Good Coating for a Radome

My club has a well used Motorola branded StationMaster UHF repeater antenna that needs to be sanded and recoated. Besides the surface, the antenna is in very good working order so we're not ...
2
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5answers
871 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?
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3answers
182 views

Substitute for Dacron rope in antennas

I am building an antenna that specifies the use of Dacron rope to help support the spreaders, but that is not readily available in Trinidad and Tobago. What will be a good replacement with regards to ...
5
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3answers
701 views

HF antenna design for high-altitude balloon

I'd like to put a WSPR or JT65-like transmitter on a high-altitude balloon, but lacking much experience with HF antennas, I don't quite know where to start. I'm thinking it will operate on 20 meters, ...
0
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1answer
68 views

Will rewiring this antenna change the characteristics?

Speaking of the antenna in this question: What kind of 2 meter antenna is this? The connections are rusted and corroded so I'd like to rewire it. If I move the shield from where it is currently ...
2
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1answer
962 views

Is it possible to determine if I'm adjusting gamma match in correct direction with an SWR meter and if yes, how?

I've recently obtained a Quad Loop antenna for 2 m and 70 cm that's fed through gamma match, as shown in the picture: The shorter metal bars are connected to the hot side of the BNC, while the longer ...
2
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2answers
139 views

Antenna experimentation

I want to make a DIY antenna for my Kenwood TH-F6A. Is there any danger of damaging the radio (i.e. by trying an antenna that is unsuitable), or is it safe to experiment?
4
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2answers
4k 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 ...
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2answers
345 views

Measured forward power less than “usual”

I've just tried making my own J pole antenna. While matching for lowest SWR on the SWR meter, I noticed that my FTM400 didn't show 5 W forward power. I hardly saw the reflected power needle move so I ...
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2answers
664 views

Linear-Loaded Cage Dipole?

I've recently learned about linear loaded dipoles as one way of building a physically shortened antenna. As I understand it, any shortened antenna will have reduced bandwidth and linear-loaded dipoles ...
2
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1answer
782 views

What material is best to design a dipole antenna working at VHF frequency? [duplicate]

I need to design an antenna using the tool FEKO. The antenna is supposed to work in VHF frequency and has a gain of around 2.2 dB. What is the best material to use and what are the specifications of ...
2
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2answers
865 views

Optimal antenna orientation for High altitude balloon?

(First of all, I hope this is the right subform, please correct me if I'm wrong) I am using a 433 Mhz LoRa Radio to communicate with a high altitude balloon and am using an antenna like in this guide ...
8
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1answer
807 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 ...
10
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1answer
2k 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 ...
0
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1answer
223 views

pull-up inductors for a differential PCB trace antenna

Trying to figure an antenna for the Si4012 RF chip. Page 26 of https://www.silabs.com/documents/public/application-notes/AN639.pdf talks about feeding the two sides of the loop antenna through two ...
3
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3answers
4k 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. ...
5
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2answers
2k views

What ways are there to extend an antenna?

I am using an arduino micro controller with a LoRa radio module to communicate. The shield has 2 ways of connecting an antenna: either a SMA jack or a hole for soldering. Now my problem is this: I ...
3
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3answers
877 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 ...
5
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1answer
526 views

Necessary spacing for 1 kW Gamma Match on 144 MHz

I'm working on a 144 MHz antenna using a gamma match. The best result (resonance 50+j0 at 144.400 MHz) I reached is a 10 mm diameter gamma rod, 15 cm long and a capacity of 10 pF. I thought to obtain ...
5
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1answer
981 views

What is the difference between “Cross Polarized” vs “Circularly Polarized” Antennas?

What is the difference between cross-polarized yagi antennas and circularly polarized antennas?
3
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2answers
667 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 ...
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2answers
422 views

Choosing a type of array antenna

I want to design a steerable beam array antenna which has 15 dBi directivity using uniform fed infinitesimal dipole elements at 1GHz frequency occupying physical aperture. Considering that phases of ...
5
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1answer
618 views

Does the wire/conductor size of all the elements affect antenna bandwidth?

Does the wire diameter of the reflector and the directors of a beam antenna affect the bandwidth or is it only the driven element diameter that has this effect?
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2answers
1k views

Hentenna beam…is it possible?

I did a (Amateur Radio) search for 'hentenna' and got not one hit. So, to boldly go where no man has gone before, I want to explore the strange new world of creating a beam antenna with Hentenna DE, ...
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2answers
1k 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 ...
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8answers
10k 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 ...
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2answers
1k views

Dipole versus ungrounded end fed for HF RX

I've built a 2 meter ground plane antenna that works pretty well for RX and has a decent SWR on 2 meters with my Alinco. However, I'm experimenting with SDR quite a bit and would really like to build ...
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2answers
94 views

Identify these components

First post here yay! I am repairing Shengda sdhf dual band antenna (looks similar to a Comet x50) it showed a SWR of >3 on both UHF and VHF. I opened it up and the only connection I could see ...
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2answers
153 views

Interpretation of NASA design

I'm very interested in replicating a design published by NASA here : https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19670027843.pdf Specifically the arrangement on Page 11. I have a similar ...
4
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1answer
514 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 ...
8
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3answers
286 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 ...
8
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2answers
1k 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 ...
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1answer
300 views

RCA victor 35x tube radio loop antenna replica?

There is this one youtube video I have not been able to find again, where someone with a similar model radio was making replica of the original loop antenna on the back. I am wanting to make a ...
4
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1answer
97 views

Steel Directors with Copper DE

I found old plans for a quagi that uses copper for the Reflector and Driven Element and any 1/8" metal available for the directors. The general recommendation for antennas is: no steel for the DE. Is ...
6
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2answers
5k 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, ...
4
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2answers
928 views

Cross Yagi Antenna Design

What will be the effect if I add the insulation between elements and metallic boom of the cross yagi antenna (where elements from outside of the boom, instead of through boom) and in this case boom ...
2
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1answer
2k views

Balun and impedance matching suggestions for dipole antenna

I'm a newbie who is attempting to build a half-wave dipole antenna that will be located in the rudder of a sailplane. 123.3 MHz is the most important frequency to me, although it's reasonable to ...
0
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1answer
82 views

What parameters are currently possible in a directional antenna less than 5mm long?

I'm curious what kind of directional antennas could fit inside a cell phone, which would require it to be 5mm or less in its longest dimension. I know that the length of a directional antenna is often ...
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3answers
1k views

Better antenna for 433 MHz

I am using a FS1000a Transmitter and a MX-RM-5V Reciever for transmitting Sensor Data inside my flat to an Arduino Device. (13 Chars every 10 Seconds) The same Transmitter type is also used for ...
6
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1answer
7k 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?
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1answer
296 views

What are the wire lengths of the RadioWavz OCF 40m dipole?

I was recently gifted the RadioWavz DX40 Short sans wire. I have the balun and the wound inductor, but can't find any information as to the proper lengths of wire for this antenna. I can find general ...
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2answers
576 views

Airband VHF antenna challenge

I have a very difficult antenna design/installation challenge. I need to install an VHF antenna (118 to 140 MHz) into a nearly all carbon fiber glider. The radio provides 5 watts and 50 ohm, and most ...
9
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2answers
3k 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 ...
5
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1answer
900 views

Minimum thickness of whip antenna

I'm looking at designing a communication system using very low power transmitter (0.1 W) and operating in the 400 Mhz range. For my uses I think a quarter wave whip antenna would work well, so I've ...
6
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1answer
1k views

Are there easier ways to make traps than coax and plastic pipe?

I recently built an antenna for my attic inspired by http://degood.org/coaxtrap/. I found making the coax traps very time consuming and frustrating to tune. I got to thinking about 3D printers, and ...
8
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1answer
4k 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 ...
8
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3answers
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 ...