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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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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
1 vote
2 answers
267 views

Is a "shorted" coax feedline ok for a G5RV type antenna?

I have "inherited" what I believe to be a G5RV antenna with two 51 foot wire centerfed radiators. If I remember correctly from measuring 2 months ago, there is about 31 feet of 450 ohm ladderline ...
Bob Horton's user avatar
2 votes
1 answer
127 views

RF inert adhesive for building antennas in the UHF to low GHz region

I want to experiment with different mechanical designs for some Yagi antennas for 440 MHz through perhaps 2.3 GHz. I am looking for some adhesives and/or potting-like materials that would be ...
mike65535's user avatar
  • 1,035
3 votes
3 answers
596 views

How do I get my crystal radio to receive?

My 8 year old and I are trying to figure out how to get this crystal radio we made working. It's based off this youtube video. We get clicks when we put the crystal ear piece either side of the ...
Agent Zebra's user avatar
4 votes
3 answers
1k 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-...
Aaron Kreider's user avatar
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
5 votes
2 answers
1k 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 ...
Aurelia Peters's user avatar
1 vote
1 answer
126 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.
user3341402's user avatar
5 votes
2 answers
9k views

Can I use a CB antenna with a ham radio?

I just passed General and purchased a FT-450D with an internal antenna tuner. While my ultimate plan is to use a G5RV, it will be a while before I can get it up. What modifications would I need to ...
Adam KC0DAD's user avatar
3 votes
2 answers
752 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 ...
Lance's user avatar
  • 941
4 votes
3 answers
237 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 ...
bigaone22's user avatar
3 votes
4 answers
4k views

Optimising a small magnetic loop with 1:1 SWR but little radiation

I'm trying to build a small magnetic loop for 5W on at least 40m - 20m following ideas of G4ILO's wonder loop. For this, I'm using coax with a ~2mm copper core and ~1mm spacing to the braid (see 1st ...
user avatar
3 votes
3 answers
1k views

Effect of paint / uv coating on velocity factor of PVC

I own an Ed Fong TBJ-1 antenna, which is like a twin-lead J-Pole with a coax stub and some inductors added. It's enclosed in an unfinished PVC pipe. I'm tempted to paint the PVC with non-conductive ...
user3486184's user avatar
  • 1,957
0 votes
1 answer
72 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 ...
Lance's user avatar
  • 941
5 votes
3 answers
1k 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, ...
Rodney Price's user avatar
5 votes
3 answers
1k views

Tiger Tail + capacitive coupling... what's the interaction?

I've been working on a 2m setup for hiking. My goal is to have the best possible antenna that can be used while walking, and that won't get damaged if I walk under a low branch or some other forest ...
Dr Marble's user avatar
  • 171
5 votes
3 answers
3k views

Does a receiving antenna need radials?

I am very new to radio and am using two 433MHz 1/4 wavelength monopole antennas to send and receive data. On the transmitting antenna I'm going to add radials (as it is the standard in my application)...
user5227744's user avatar
2 votes
1 answer
989 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 ...
Nat's user avatar
  • 21
2 votes
2 answers
156 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?
jcadcell's user avatar
  • 207
1 vote
2 answers
999 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 ...
William's user avatar
  • 813
2 votes
2 answers
1k 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 ...
user5227744's user avatar
0 votes
1 answer
321 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 ...
kellogs's user avatar
  • 205
5 votes
2 answers
3k 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 ...
user5227744'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
5 votes
1 answer
1k 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?
metropolis'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
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
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
854 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?
Mein Tenah's user avatar
1 vote
2 answers
98 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 ...
Gerrie's user avatar
  • 123
2 votes
2 answers
157 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 ...
Kontakt's user avatar
  • 155
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
2 votes
2 answers
2k 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, ...
Mein Tenah's user avatar
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
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
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
4 votes
1 answer
112 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 ...
Mein Tenah's user avatar
0 votes
1 answer
399 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 ...
Chris Manning's user avatar
1 vote
2 answers
514 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 ...
Hans Neve's user avatar
  • 227
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
2 votes
1 answer
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 ...
Chris Young's user avatar
0 votes
1 answer
91 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 ...
B T's user avatar
  • 101
3 votes
4 answers
611 views

Plastic predator bird props --- Are they effective? How to mount them?

Are plastic predator bird props any effective at keeping away real birds from our antennas? Can I mount such a plastic predator bird with screws or does it need to wiggle in the wind to be effective? ...
on4aa's user avatar
  • 1,317
1 vote
3 answers
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 ...
Triscus's user avatar
  • 113
1 vote
1 answer
501 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 ...
Patrick's user avatar
  • 111
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
1 vote
2 answers
715 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 ...
Chris Young's user avatar
5 votes
1 answer
612 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 ...
Kevin White's user avatar
1 vote
3 answers
490 views

Bandwidth, Q-factor, Radiation Eff calculations

Is it possible to give approximate answers about what an antenna is capable of? There are a lot of formulas out there, but every single one I found is based on actual measurement; input, output, SWR ...
Aard's user avatar
  • 41
2 votes
1 answer
341 views

How do I simulate a receiving antenna in EZNEC simulation tool?

I have a situation where I need to find receiving antenna impedance when it’s $\lambda/2$ distance from the transmitting antenna. Both are dipole antennas. Is it possible with EZNEC?
Shiva Mudide's user avatar