Questions tagged [wire-antenna]

Anything to do with wire antennas, including how to build one, how different wire antennas perform, how to tune them or when to use a balun, and what types of wire work best in certain antennas.

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35
votes
7answers
37k views

Using a balun with a resonant dipole

I am preparing to construct a resonant, center-fed, horizontal dipole. I have seen people use baluns at the feedpoint of the antenna, and some people swear by them, but I have never gotten a ...
17
votes
3answers
2k views

What is a “random wire antenna”?

Some antenna tuners claim to match any “random wire” to any HF frequency. Can one really use a random wire as a practical antenna system? From everything I have heard, the resonance of the antenna (...
16
votes
3answers
10k views

What is the peak voltage at the tips of a dipole antenna?

What is the peak voltage present at the very end tips of half-wave dipole antenna in free space, and how might this peak voltage relate to transmitter type, transmitter power, RF frequency vs. antenna ...
14
votes
5answers
44k 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?
12
votes
3answers
8k 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 ...
10
votes
1answer
5k 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" ...
9
votes
2answers
2k 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 ...
9
votes
1answer
462 views

Tuning a wire antenna by folding

Last weekend we tuned a quad loop for 80 m and 40 m. Instead of cropping, we folded the isolated wire using cable ties as shown in the picture below. After folding several quite large sections of the ...
8
votes
5answers
1k 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 ...
8
votes
3answers
275 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
votes
3answers
3k views

Could a weather balloon make a good antenna?

I can't afford a massive tower, but I can get a weather balloon. What kind of set up would work best to get the maximum efficiency out of altitude?
8
votes
3answers
318 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 ...
7
votes
4answers
770 views

How would you get an “I'm alive” message to family in another state using amateur radio?

I'm researching options for getting an "I'm alive" message during a disaster response out to family in another state that aren't HAMs. There are likely to be a lot of possible answers that are art ...
7
votes
7answers
33k views

End-fed wire antenna lengths

I want to use an end-fed wire antenna, but what would be the best length of wire for the 20m and 40m bands? Is there a way to work this out? This is assuming a tuner will be used.
7
votes
3answers
233 views

Passively reducing ground loss?

Would a disconnected wire or conductive mat below a low height antenna reduce ground losses? A tuned length of wire under a wire antenna might be suitable for NVIS gain. But would a bunch of space ...
7
votes
2answers
2k views

Practical 80m vertical wire antennas without radials?

We'd like to install an antenna for 80m at our club/contest station. Our club, OH2K, is housed at a school, and we can't fill the roof with a radial mesh. The roof is not metallic itself, either. We ...
7
votes
2answers
657 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 ...
6
votes
4answers
6k 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 ...
6
votes
3answers
653 views

Can an antenna be too powerful for certain receivers?

I'm brand new to shortwave radio and have been researching what kind of a receiver to get. I'll use it on the antenna I'll build (longwire, 50-100 feet) for shortwave listening; no transmitting. Right ...
6
votes
2answers
109 views

Effective Area of Dipole Array

I'm trying to design a low frequency dipole interferometer antenna array. I am realizing how little I know about radio antennae. I'm confused by the concept of effective area $A_e$ and how it applies ...
6
votes
1answer
998 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 ...
5
votes
3answers
547 views

Cheap antenna for new HF HAM

I just got a 100W HF radio and I am new at this. What is the cheapest antenna I can hook up without burning up my radio or shocking myself?
5
votes
5answers
834 views

Loop antenna layout and radiation?

I've got, for the near term, limited resources to put up an HF antenna at my home. One of the options I can manage without excessive cost is a loop, which would enclose the house. I need to transmit ...
5
votes
2answers
1k 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 ...
5
votes
5answers
485 views

Signal path to maximize RFI rejection in an urban environment

Urban ham here (Cambridge, MA - FN42ki - KC1JZE) looking for tips to make this hobby possible in the city. I rarely can hear both sides of HF phone transmissions, and have yet to make contacts despite ...
5
votes
3answers
616 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, ...
5
votes
2answers
4k 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, ...
5
votes
3answers
4k views

What type of solder is best suited for radio and electronic use?

Many types of solder are available today, such as acid-core, silver, rosin-core and aluminum solder. What kind should I use for building antennas and radio equipment? Why? From test question: T7D08
5
votes
2answers
804 views

Can I use old TV FM card as SDR?

I tried searching a lot before, but couldn't find anything about it; I have an old TV/FM card from an old computer, I wish to know if it can be used as an Software Defined Radio, and if yes, how? The ...
5
votes
2answers
5k views

What is the impedance of a 1.25 λ dipole antenna?

I would like to make a dipole antenna. This particular antenna is used for reception only; no transmission is involved. I would like to receive as much power as possible by this antenna as it is used ...
5
votes
3answers
518 views

Why a capacitor is needed in Fuchs antenna?

I tried to understand the physics of Fuchs antenna and there is one thing that I don't quite understand. This is probably a very silly question, but I spent a lot of time looking for an answer (books, ...
5
votes
1answer
129 views

Are there reasons why a receive-only wire antenna should not be λ/2 in length?

The answers to this question explain why it's difficult to transfer power from a transmitter to an antenna that is λ/2 in length (or a multiple for long wires, or as half a dipole's length). Are ...
5
votes
1answer
406 views

HF/VHF antenna for high altitude balloon

I'm working on the design of a dual band transmitter for use on a high altitude balloon. I'll be transmitting on 2 meters and 20 meters (APRS and WSPR) with about 50 mW. To keep the weight to an ...
5
votes
3answers
1k views

EFHW works only on one band - what am I missing?

I tried to build a multiband EFHW antenna as described in articles by PA3HHO, PD7MMA, G0KYA and many others. I decided to start with a short 40/20/(15?)/10 meters version without any loading coils. ...
5
votes
1answer
825 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 ...
5
votes
3answers
271 views

How far the near-field reactive region extends from the transmitting antenna?

I am doing research on near-field harvesting. In my situation the transmitting antenna is a dipole antenna operating at 2.45 GHz and its length is 14 cm long. I am trying to find how far near-field ...
5
votes
2answers
184 views

Theoretical Wifi antenna not working for the expected range

You buy a "20dBi omni" Wifi antenna, operating in the 2.4-2.5GHz band. You note that the expected range is not achieved from this 300mm long antenna. What could be wrong? Can someone please tell me ...
4
votes
4answers
881 views

Is string trimmer line suitable for supporting antennas?

In searching for suitable materials for a wire antenna, I found a few mentions of using string trimmer line to hold up each end of the antenna. This would be a nice option as it is readily available ...
4
votes
2answers
562 views

Ferrite beads on a wire antenna?

Will putting a ferrite bead or beads near (but not at) the end(s) of a wire antenna electrically lengthen or shorten it? (lower or raise its resonant frequency)?
4
votes
6answers
1k views

Tune a very short 3-5m random wire for 40m (around 7.030 MHz) for listening or occasional QRP CW sending

I would like to use a small trx first for listening CW on 7030 kHz and then for transmitting, locally, among friends. My conditions are "prohibitive" as for antennas: a block of flats, 4th floor in ...
4
votes
3answers
313 views

Antenna suggestions for 160m band in smallish yard?

I have a decent-sized but not huge yard (roughly 50x100' / 15x30m) and I'd like to get on the 160-metre band. It's hard enough to get out on this band so I'm looking to do something reasonably ...
4
votes
2answers
2k 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,...
4
votes
3answers
3k views

Recommended 9:1 unun core type(s)

I would like to construct a 9:1 unun that connects my QRP transceiver to a random-wire antenna. The transceiver's antenna connection is an unbalanced BNC jack and the random-wire antenna is, well, a ...
4
votes
2answers
213 views

Antenna Design for specific directions

I am designing an antenna for a device and was hoping to gain some insight in the correct design direction for the antenna. The Idea: A receiver & antenna that fits in a 6" diameter by 3" deep ...
4
votes
1answer
102 views

Dipole symmetry?

In ideal free space, both arms of a tuned wire dipole will be of identical length. However, the real world is not perfectly symmetric free space. The support heights, ground levels, ground ...
3
votes
2answers
471 views

How does an E-Z-O Antenna work and why does it appear in Wikipedia's article on quad antennas?

How are the conductors/radiators in the E-Z-O Antenna configured, and why is it described in Wikipedia's article Quad antenna? I see three circles and a spider web of wires inside each, but from an ...
3
votes
2answers
2k views

HF SWL antenna wire? Will plain 16-Gauge copper wire work well enough?

Planning to set up a HF antenna for RX-only. However, I can't decide what kind of wire to use. I want to buy something new. My first thought is to buy a spool of 16 Gauge copper wire, but am hoping ...
3
votes
2answers
90 views

4:1 Balun question

With an OCF dipole, does it matter which leg, short or long, is connected to which side of the 4:1 balun, hot(coax center) or shield? How can you tell which is which, the balun is not marked. Thank ...
3
votes
1answer
672 views

How to probe a dipole antenna?

I want to start experimenting and tinkering with antennas, starting with ½ wave dipoles. I will be measuring the AC voltages on both the transmitter and the reciever antennas simultaneously. And by ...
3
votes
3answers
755 views

Suggestions for HF antenna for occasional use on my sailboat

I have had a license since I was a kid, but have not touched anything ham radio related in years. I have been thinking about diving back in and combining it with my sailing. I'm looking for thoughts ...