Questions tagged [antenna]

Questions about the design, selection, building, testing, mounting, or properties of antennas. See also specific tags: [antenna-theory], [antenna-construction], [dipole], etc.

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2 votes
4 answers
573 views

I'm looking for an effective beam antenna for both 20 meters and 10 meters

My favorite HF bands are 20 meters and 10 meters. I am currently using a multi-band vertical antenna, but it's not so great for DX'ing. I am looking for a good upgrade. I'm still learning a lot about ...
0 votes
1 answer
6k views

My Baofeng radio can transmit and hit a repeater 50 miles away but it isn't receiving [closed]

My radio won't receive. Help? It literally went dead and I still have the rubber duck antenna
3 votes
5 answers
11k views

If i connect two antennas to one radio using a t connector will it work?

If I connect two antennas to one radio using a t connector will it work? If a connect 2 antennas (a mag mount + a dipole?) to the same radio with an adapter will it work normally on 2M band and will ...
0 votes
3 answers
48 views

SMA Connector Impedance

I am new to antennas, and am trying to create a monopole that connects to an SMA female to transmit a 2.4ghz wifi signal. I know that the antenna needs to be a multiple of 3.1cm in order to have the ...
2 votes
1 answer
186 views

High electrical noise only when coax shield is connected

I'm trying to understand a noise issue on my Yaesu FT-891. I have very high 60 hz electric buzz on most bands with 40 and 15M being the worse at about S9+. My antenna is a MyAntennas 66ft EFHW fed ...
3 votes
2 answers
79 views

Antenna reciprocity how does an antenna increase receiving range?

According to Wikipedia antennas are reciprocal unless they're constructed of nonreciprocal materials. There are a multitude of mathematical formulas which unfortunately I'm unable to understand due to ...
2 votes
1 answer
48 views

Do I need an antenna tuner for new mobile antenna

I am looking to buy my first mobile antenna, for use with a 2m/70cm HT in the car. The HT needs 50 Ω impedence. I was looking at this antenna, but another ham told me that I need 1/4 wave or 5/8 wave ...
4 votes
1 answer
67 views

Using old vehicle through glass cell antenna

My old (2001) Seville had a cell phone with antenna mounted on the rear glass. The coax connects inside the glass, with signal passing through the glass to the whip mounting plate. I'm wondering if I ...
1 vote
1 answer
62 views

Can an antenna be affected if mounted to a bull bar?

When I say 'mounted to a bull bar' I mean the antenna being metal on metal contact to the bull bar without any rubber or fiber glass keeping the materials from touching. Could this affect the ...
1 vote
3 answers
1k views

What is the best type of feedline for a base UHF VHF ground plane antenna with a distance of around 50-75 feet of coax?

I'm going to be putting up a Comet GP6 UHF/VHF Ground Plane Antenna. It will be chimney mounted to a mast, and the total height is around 40 ft. The upper half of the chimney starts at the first ...
4 votes
2 answers
102 views

does the shape of an antenna ground plane matter?

I would like to test a tranceiver setup I created before I mount it in my car. In my backyard, there's a length strip of metal; 10m in length, 10cm wide. Now I wonder if I can use that as a ground ...
19 votes
5 answers
15k views

Why do folded dipoles have greater bandwidth than ordinary resonant dipoles?

This is something I've read in passing, but never encountered an explanation of why. For example, Wikipedia says: Another common place one can see dipoles is as antennas for the FM band; these are ...
2 votes
2 answers
1k views

What is pinout for headphone FM radio antenna?

My Android phone (as many others) have FM radio receiver on-board. But apparently, it has no internal VHF antenna at all, since there is no signal at all w/o headphones plugged in and sound quality ...
5 votes
4 answers
435 views

How can I inject an oscillator output into the RF input to my radio?

I have a Bodnar GPS disciplined oscillator, and I would like to inject its output into the antenna input to my HF rig. This will allow me to compare the frequency of received unknown signals to the ...
0 votes
2 answers
63 views

NooElec for Startup HF Communication

I am working on setting up a Ham Radio shack for long distance communication on the HF frequency. The goal is to transmit 1,200km from Alberta to Manitoba using skywave propagation. I would need to be ...
5 votes
2 answers
138 views

What happens if I “open” a folded dipole so that the two wires are not connected anymore?

A folded half wave dipole consists of two wires in parallel with only one of the wires driven, but the ends of the two wires electrically connected. As I understand it (and I may well be wrong there) ...
2 votes
2 answers
60 views

Type of Ground Wire for an AM Crystal Radio - I'm using a longwire antenna

I have way too many choices for ground wire. I am using a crystal radio so I need the BEST not just what will 'get by'. I've seen solid copper 10gauge, aluminum wire etc. I've also seen wide ...
2 votes
1 answer
54 views

cut or lengthen to reduce swr on vertical wire antenna

Have tried measuring antenna wire using formula 234/frequency for 1/4 wave vertical but this gives high swr. How do I lower swr on a wire vertical antenna. Do I Cut or Add? wire'
5 votes
2 answers
117 views

How do antennas over 1/2 wavelength work?

I've been told countless times that an antenna should be 1/4, or 1/2 wavelength. That increasing this size to a higher multiple of 1/4 will work, but it will distort the radiation pattern to include ...
3 votes
1 answer
61 views

Route cables on the inside of the tower?

I was visiting a customer site who had their equipment fried by lightning and granted they forgot to install surge protection, so that's most likely what did it, however I also noticed they had the ...
3 votes
3 answers
172 views

Will two nearby yagis on different bands interfere when transmitting at the same time?

I'm working on a digital ham radio project that will require two 2m and/or 70cm yagi antennas to be transmitting and receiving in somewhat close proximity to each other. Each will have it's own ...
5 votes
3 answers
816 views

Noticeable difference between trunk and roof mount?

Between trunk-mounting and roof-mounting a 2m/70cm antenna, both as through-hole NMO mounts, is there really that big a difference performance-wise? I mean, I know roof mounting is better, but let's ...
2 votes
2 answers
181 views

Where can I find information regarding RESONANT long wire antennas?

So multiples (by 3x-5x) of full wave lengths long? It's my understanding that you can build an antenna that is 802.28 feet long and it's naturally resonant WITH GAIN on all the usual Field Day ...
0 votes
3 answers
193 views

Can I use a car antenna intended for 2m/70cm on a 868mhz Lora device?

I have a Lora radio device that runs at 868mhz, it came with a tiny stubby antenna. I want to use the device out and about so wanted to know if it will be OK connected to a magnetic/car antenna I got ...
3 votes
3 answers
768 views

Improve AM reception on an old Walkman that has no external antenna

I have an old Philips walkman that has AM/FM radio. I tried AM radio. Really I can get clearly 2 country radios. I caught very poorly 4 foreign radios or different countries, but they have lots of ...
0 votes
3 answers
94 views

Extend transmit range of my HT

Based on comments and new information I have rewritten this question entirely: I need advice on a simple, inexpensive, and non invasive (no holes being drilled in walls) way to talk to repeaters in my ...
4 votes
2 answers
231 views

Can an 'ugly balun' be too long?

Will an ugly balun exhibit adverse effects if more coax is wound onto it than the recommended 18 - 21 feet? The antenna in this instance is a 40 Meter Delta Mono Loop that suggests using 22'-6" ...
3 votes
2 answers
270 views

Squelch won't stay open on FM 2 meter band

I am currently using a Baofeng BF-F9V2+ radio. I have found that when listening, my squelch won't stay open, despite getting a good clean signal. I am using a homemade vertical dipole antenna for 2-...
5 votes
2 answers
127 views

Understanding Impedance (R+jx)

In a typical antenna (lets say dipole for this discussion), the pattern below is observed in the impedance (R+jx) graph: I'm trying to wrap my head around this graph. Why does the resistance spike, ...
2 votes
1 answer
76 views

What is the signal of a receptor antenna irradiated with a plane wave?

Let's say there is a reception antenna connected to a detection system with a coax, and a transmitter sends a plane wave. What happens is that the antenna gets a certain power, following the [...
3 votes
4 answers
426 views

Issues with high SWR on HF Kits EFHW 49:1 UnUn kit

I recently tried assembling a EFHW kit, and some problems came up in testing. I believe this is the kit; I bought it through ARRL: HF Kits website. This is my first time making an UnUn and EFHW kit. ...
1 vote
0 answers
85 views

Is this amount of loss normal with LMR400?

I have a run of about 150 feet of LMR400 (specifically, it's this DX Engineering "400MAX" product). It connects to an Ed Fong antenna (2m, 1.25m, 70cm tri-band J-Pole) about 75 feet up a ...
0 votes
2 answers
228 views

Why do ham radio operators refer to current flow on the outside of coax as common mode current?

My understanding is that the desired mode of operation for a two wire transmission line is differential, where at any point along the line the addition of the voltage or current is zero, such that the ...
1 vote
1 answer
145 views

Recommendations for Antennas installation with Steep slopes

I have a property that I am trying to figure out the right antenna setup for. Transmission Goals North of this property is 900 miles to communicate 80M or 40M. Also want to communicate to another ...
2 votes
2 answers
141 views

How do I rewire a simple a.m. loop antenna that became unwound?

This antenna has been around for decades and the design is as basic as can be. Somehow the antenna I'd been using, became unwound. The total length of the wire is 4.9ft. I need to know the proper ...
0 votes
3 answers
131 views

ELF antenna receiver build instructions?

I built a vlf receiver in the nineties but good grief, that's a long time ago and have looked very little at receivers since. I'm interested in frequencies from 12 - 18 Hz. Looking at the following ...
19 votes
2 answers
30k views

How does a mag mount antenna achieve a ground plane?

I've been thinking for some time about magnet mount mobile antennas and wondering how they establish their ground plane. Consider that many mag mount antennas have some kind of protective coating on ...
0 votes
1 answer
80 views

YouLoop antenna for amateur satellite reception

I recently learned about the commercial YouLoop antenna and it seems to be quite simple to set up. They said it was possible to receive satellite signals on amateur VHF (e.g. NOAA and other CubeSats ...
24 votes
2 answers
5k views

How do Handheld antennas work without ground?

Dipoles have the 2 wires going to each leg of the antenna completing the circuit. Big AM towers use the second wire as a ground plane But how do handheld rigs transmit and receive with just one wire ...
-2 votes
3 answers
125 views

Radio without antenna?

Is it possible that there will ever be a radio system that does not require antennas? (Not small embedded antennas for microwave radios, but radios that actually do not have antennas)
-1 votes
1 answer
69 views

Transmission power of Apple Wi-Fi antennas (EMF and health)

(I hope this is the right place for this kind of question) Background I was looking a little bit into how Wi-Fi affects our health topic. While many people seem to be concerned about their Wi-Fi ...
9 votes
2 answers
2k views

Why are longer antennas not suitable to pick higher frequencies?

I know that the length of an antenna depends on the wavelength of the frequency it's trying to receive. A higher frequency needs a shorter antenna and vice versa. I can see that with a high frequency ...
5 votes
1 answer
319 views

EFHW: better to get far end really high, or middle somewhat high?

I built a 40m end fed halfwave antenna and unun, and the wire is about 66 ft long. I have some tall trees nearby I can hang it in, semi-permanently. Which of the following would be better? A) hanging ...
4 votes
2 answers
352 views

VNA basics, antenna coax cable

Recently purchased my first VNA (Nano VNA) and I'm trying to learn the basics. I have a 150MHz 1/4 wave whip antenna that I need to install on a large metal object so I was hoping to use a VNA to help ...
1 vote
2 answers
117 views

Small shortwave (20MHz) directional antenna design

I'm trying to do some basic radio astronomy experiments, and I'm currently working on picking up radio bursts from Jupiter. These are emitted at around 20MHz; for all intents and purposes, Jupiter is ...
1 vote
2 answers
65 views

How should coax be physically wired to a "stud" mag mount?

I picked up a variety of antennas at a swap meet a while back, and am having trouble characterizing an unlabelled HF (or low VHF?) vertical element that screws into a stud in a magmount I also brought ...
2 votes
1 answer
102 views

Phase-tuning Yagi-Uda antennas

Related to my earlier question around the TET-Emtron HB35C antenna. It is advertised as a: The HB35C is a full size tri-bander, efficiently utilising the DUAL DRIVE HB9CV system with the ...
2 votes
1 answer
105 views

Cleaning an oxidized NMO Mount

Before going through a car wash, I took my mobile antenna off its NMO mount and it looks like water seeped in through the threads. It's not corroded (i.e., there's no metal flaking off) but it's not ...
1 vote
1 answer
103 views

AX.25 protocol packet size

I am new to the world of amateur radio and I am carrying out a university project concerning the communication between satellites and ground stations. My question is: What is the packet size of the AX....
5 votes
1 answer
327 views

What's the effect of directly connecting ladder line to coax?

I was watching a video where ladder line (450-ohm) was directly connected to coax (50-ohm) without a matching transformer. Mating your Coax to Ladder Line Wouldn't this mismatch make it impossible to ...

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