Questions tagged [loop-antenna]

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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 ...
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0 votes
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44 views

What is the differece of a large loop antenna and a small loop antenna in terms of their response to an electromagnetic wave?

there is something that I dont get. I read that a small loop Antenna (also called magnetic loop) responses more to the magnetic field than the large loops does. I was wondering why this is the case ...
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6 votes
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How does Large Loop Antenna work physically?

I am learning about loop antennas at the moment. I read that the respone of a small loop Antenna is propotional to the rate of change of magnetic flux through the loop which causes a uniform current ...
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2 answers
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Is it necessary to have a "loop" antenna to make the primary antenna work?

I know nothing of ham radios. However, my elderly uncle, who lives next door to me has a ham radio. He has a very tall antenna. He gets a friend of his to string what looks like to me, an "air ...
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5 votes
1 answer
272 views

Why are loopstick ferrite antennas commonly wound with Litz wire?

What is the advantage of using Litz wire to wind ferrite (loopstick) antennas? How much of an advantage in what characteristic does this type of wire provide? (over generic single strand enameled or ...
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4 votes
1 answer
459 views

Debugging SM0VPO's spiral loop antenna build

I had built SM0VPO's spiral loop antenna. And here it is. Recently I got myself a NanoVNA to see how finnicky it is to be tuned with that poor man's tuning cap. I brought it from 12 MHz into the 14 ...
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1 vote
2 answers
263 views

Loop Antenna Construction

I have a loop antenna. When I connect the probe from my oscilloscope, does the probe also act as an antenna? If so, how should I fix that? I read about feeding technique, but I still do not ...
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2 votes
2 answers
1k views

Multi-turn large/full-wave loop antennas?

There seem to be lots of descriptions and/or articles on using multiple turns of conducting element in small magnetic loop antennas (STLs). But I haven't found any information on full size full wave ...
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1 vote
2 answers
141 views

Amplified RX-only loop antennas for DX operation?

I was reading up on the different amplified loop antennas, like the W6LVP or the MLA-30. Most reviews say "great reception", or show a SDR waterfall with a lot of stations, or show a random station ...
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  • 1,159
0 votes
1 answer
48 views

On a horizontally setup 20m delta loop I am looking to determine the calculations for the proper length of a feed wire

Base of loop will be about 6 feet above ground. RG-8 or 213 will be used for the feed wire. Ugly balun as well.
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2 votes
2 answers
1k views

Is a balun really necessary for a small loop antenna?

I am in the process of designing a small receiving loop antenna for the lower HF bands. By small I mean a circumference of less than $0.2\lambda$. Thus, a uniform current distribution can rightly be ...
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2 votes
3 answers
577 views

Why is self-resonance important in a loop antenna?

I visited a "small loop antenna" calculator web site today and fed in my horizontal loop gepmetry, curious to see what it would say. 2" dia wire, 72' circumference, 3.935MHz. Interesting results, ...
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4 votes
2 answers
170 views

Basic antenna matching theory?

I'm fairly new to antenna matching, other than having built a base loaded vertical. I'm also new to EZNEC and I tried to simulate an horizontal loop. I arbitrarily chose a 10x10M loop, so I added 4 ...
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5 votes
5 answers
2k 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 ...
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1 vote
1 answer
513 views

cubical quad reflector tuning stub design

I am currently building a two element portative cubical quad with one reflector and one driven element. the conductors of the driven element and reflector are encased in pvc tubing. I was wondering ...
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9 votes
4 answers
640 views

Why are there differences in antennas that depend on electrical component and magnetic component of a radio wave?

I understand the idea that when we are targeting the electrical component of the radio waves we need to have some form of a linear conductor that receives the electrical component, this creates a ...
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  • 169
2 votes
2 answers
438 views

Choke at feed point of delta loop with Q match

I am working on putting together a 40 meter delta loop using a 1/4 wavelength of RG-6 as the matching section. However I'm unsure of where to create my feedpoint choke. Do I coil up the RG6 right at ...
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3 votes
3 answers
1k views

How do active loop vs. passive loop differ in terms of noise rejection?

As a urban ham (Harvard Square, Cambridge MA), I'm on the hunt for RFI rejecting antenna configurations. After hours of research, I've come across many strong recommendations for loop antennas, since ...
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0 votes
2 answers
268 views

Can a Loop Antenna send and receive 10,000 miles away

Can we expect a Loop Antenna such as a Chameleon F-Loop Antenna transmit and receive from the USA's midwest to Australia on HF using an average 100 watt SSB transmitter and an average receiver? If so,...
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2 votes
2 answers
176 views

Physics behind this decametric radio telescope

I am following this design for a simple decametric radio telescope. I understand the principle that a radio wave hits the metal inducing an electric current that can be measured, but I do not ...
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3 votes
1 answer
196 views

interdigital (finger) capacitor bank for fine tuning of differential loop antenna

I am attempting to implement a PCB trace antenna; namely the sample in this document. Thing is the 1.17 pF for Cp1 is quite hard to achieve in a cost efficient manner with 0603 caps (I loath those ...
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  • 199
4 votes
3 answers
6k views

Antenna tuner design

In a related question about a broadband antenna for SDR it was suggested me to build or buy an antenna tuner. Since maybe it was not clear to everybody, I'm designing an antenna tuner for reception, ...
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2 votes
1 answer
548 views

Rules of thumb for large ("somewhat" full wavelength) loop antennas?

I would like to put up a relatively large loop antenna to cover all the HF bands. I have sloping terrain and geographically in a slight "bowl" with hills and/or ridges in many directions. If I stick ...
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0 votes
1 answer
182 views

Feed line direction for Quad antenna

I am currently getting my EE degree, and I'm trying to build my first antenna for a weather balloon. I understand with a dipole, you want the feed line perpendicular to the antenna for at least l/4, ...
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2 votes
1 answer
1k 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 ...
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3 votes
1 answer
1k views

maximum distance omnidirectional antenna

I want to know this omnidirectional antenna's maximum distance: gain 15 dBi frequency 2400 GHz power 50 watts
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2 votes
3 answers
1k views

Why are variable capacitor plates made from aluminium?

This question comes from doing some research into small magnetic loop antennas for HF. For transmitting, these antennas are often designed with a big, variable, air (or vacuum) tuning capacitor (e.g. ...
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4 votes
2 answers
226 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 ...
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5 votes
2 answers
8k views

How to construct a loop antenna for receiving HF?

I have a unused hula-hoop in my garage, and I ran some stranded speaker wire around it once, and attached one side of the wire to the coax shielding, and the other to the coax core wire. Is this the ...
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  • 388
2 votes
2 answers
207 views

Measuring antenna characteristics without physical access?

There is a loop antenna that was thrown around an attic interior several decades ago, of long forgotten dimensions. I found the feed line. Is there a way to measure what (U.S. amateur) bands on ...
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2 votes
2 answers
2k views

Does increasing the number of turns on a loop antenna decrease frequency operation?

Lets say I want to make a VLF loop antenna for a Sub AM radio band. I don't want a full wavelength because that would be a humongous antenna. Would I wind more turns of wire to decrease the frequency ...
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2 votes
2 answers
95 views

Does propagation affect magnetic and electric fields equally?

In the HF bands loop antennas are common, which, if I understand correctly, emit most of their radio energy into the magnetic field, whereas most dipoles emit largely into the electric field. To take ...
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