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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8
votes
5answers
2k 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 ...
3
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2answers
123 views

Running mag loop feedline INSIDE the loop tube

We are building a 4 ft diameter mag loop using 1" copper tube. The coupling loop will be at the top of the loop (we are using a large vacuum cap in a weatherproof box and it is too heavy to be ...
4
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2answers
221 views

100MHz to 1000MHz Antennas for Transmit and Receive

I am building a ground and wall penetrating frequency modulated continuous wave radar. The only components that I have not been able to track down are the antennas. I need two antennas (one for ...
5
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1answer
115 views

Do Loading Coils Supply “Missing Degrees” to Electrically Short Radiators?

References are made on this and other websites to the effect that loading coils can/will supply "missing degrees" to electrically short radiators. But do they?
2
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1answer
424 views

What does co-phasing of cross-polarized antennas mean?

I was working with the 3GPP release 14.6, and it mentioned that modern communication systems have cross polarized antennas, and in order to perform beam-forming we need to co-phase our pre-coder. Pre-...
2
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1answer
59 views

Wire dipole antenna proving ground / test bench

i am considering building two movable (concrete base with wheels) non metallic poles with hooks every ten centimeters or so, in order to test wire dipoles of various sizes at various heights with an ...
6
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3answers
237 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?
3
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1answer
1k views

Twisting copper wire for a less-flexible DIY antenna

I am making DIY antenna for a home project. The antenna is going to be "V-dipole" with leg length about 53cm. Unfortunately, I didn't find a thick copper wire, but I have a lot of thin core from tv ...
2
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3answers
419 views

Do PCB antennas suit for NOAA and ADS-B?

I saw many designs for creating DIY antennas for NOAA (~137MHz) and ADS-B (~1090MHz) but never seen it in a PCB implementation. So I have a rookie question: why nobody uses PCB antennas for such ...
3
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3answers
791 views

Mounting a J-Pole and Yagi on the same mast

I have two 2-meter antennas, a copper J-Pole and a Hy-Gain VB-25FM. The J-Pole is my all-around antenna, what I use for general 2 meter stuff like connecting to my local repeaters using my main 2-...
5
votes
2answers
6k 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 ...
7
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1answer
819 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 ...
4
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2answers
2k views

Ideal antenna type for FM 2 meters?

Clearly, building a Yagi tuned for 2 meters will likely have the best directional performance. Putting that aside, I'm trying to get information on what antenna type will have the best overall ...
3
votes
2answers
225 views

Antenna design - Ground plane in simulation and in practice

For monopole antennas, the ground plane acts as another arm of an equivalent dipole antenna. I'm wondering how we can expect the behavior of that antenna in practice, because the ground plane is ...
5
votes
5answers
955 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 ...
3
votes
1answer
424 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 ...
0
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1answer
211 views

NFC coil matching - Q factor improvement

I have been trying to match my NFC reader coil of size 20*20 cm with a three element circuit - one capacitor in series, another in parallel and one resistor in parallel. I have been using Texas ...
3
votes
1answer
551 views

Is a J-pole an appropriate antenna for mounting to a steel handrail?

Last year, a group of us placed a battery-powered 2m digipeater using a J-pole antenna on a mountaintop. We're planning on doing the same this year except we plan to use a surge arrestor from the feed ...
5
votes
1answer
106 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.
2
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2answers
142 views

Thermostat wire for antennas?

While checking out the local hardware store wire section, I came across thermostat wire priced significantly lower than other types. I have been trying to determine the reason but details online are ...
3
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2answers
90 views

Making WiFi access point range shorter on purpose

Not sure if this is the right place to ask, but I'm trying to build a system of multiple WiFi access points that are spread out across a store. Since every smartphone and WiFi enabled device ...
5
votes
2answers
946 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 ...
3
votes
1answer
461 views

Microstrip Loop Antenna Design

I am trying to design a loop antenna for operation at 2.4 GHz, I would like for it to have above 2.5 dB gain at 2.4 GHz and have relatively good return loss (<-10 dB). I have started my design as ...
3
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2answers
1k views

Stabilization of an antenna pole with anchoring cables

I am mounting my first antenna. It is a TRAM 1481 (about 16' height), which will be placed on a 20' pole, on my home's flat roof (about 25' height). To properly stabilize the pole/antenna: - How far ...
3
votes
1answer
616 views

What is the turn spacing on a Helix Antenna?

I want to do some satellite communication so I thought why not build my own helix antenna. I found this page: Helix antenna design and construction details The most things are clear except for the ...
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1answer
213 views

Yagi elements connected to boom?

I'm considering building this yagi for some local contests: http://www.i1wqrlinkradio.com/antype/ch90/chiave3.htm. The question is should the elements be electrically connected to the boom or not? I ...
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2answers
152 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 ...
3
votes
3answers
318 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 ...
1
vote
1answer
92 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 ...
3
votes
3answers
564 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
votes
2answers
720 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
100 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
316 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
728 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?
4
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3answers
166 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 ...
2
votes
1answer
396 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 ...
5
votes
3answers
635 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
67 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
votes
1answer
802 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
votes
2answers
137 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
votes
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 ...
1
vote
2answers
292 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 ...
1
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2answers
605 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
votes
1answer
734 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
votes
2answers
832 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
votes
1answer
749 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
votes
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
votes
1answer
200 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
votes
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 ...