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Questions tagged [antenna-theory]

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Designing antennas, selecting antennas for specific applications, properties of a given antenna design.

490 questions
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3 votes
3 answers
235 views

I keep hearing the recommendation to make your SWR as low as possible and that would imply good tuning. I'm a new HAM and made a centre-fed half wave fan, 40m, 20, 15m. It works, and pretty well. I ...
lornop's user avatar
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1 vote
0 answers
122 views

Conversion from nec2 geometry to x3d or some other format to read nec2 geometry files into (ultimately) OpenEMS would I think be good. I found a reference in a document ...
Pete's user avatar
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2 votes
2 answers
255 views

I read about using a SLINKY out in the field for an antenna. Sounds easy, doesn't it? Well, how does one go about identifying the length needed for the band of interest? Assume that the slinky has a ...
Ron K5TDF's user avatar
  • 91
1 vote
1 answer
100 views

Can I just check my understanding with any friendly antenna experts....... I am researching the normal mode helix antenna where the maximum radiation is normal to a wire helix. In the antenna books a ...
mpcengineer's user avatar
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4 votes
0 answers
116 views

There are research and examples of "fractal antennas" where the radiator is in a "fractal-like" shape, mostly to save space. Those antennas often come with a penalty in gain (...
Ryuji AB1WX's user avatar
  • 3,971
-1 votes
2 answers
228 views

I was just curious if this is even possible as a compact set up or if it is possible period. It would only have to transmit a short range, maybe 1000 feet or so?
Kev's user avatar
  • 9
2 votes
1 answer
248 views

I've recently created an yagi-uda antenna for 2m and 70 cm - specifically for 145 and 433 MHz. 8 elements for 2m and 14 elements for 70 cm. I've put 2m on MMANA-GAL and optimised by myself the 70 cm ...
LaCrimen's user avatar
  • 23
1 vote
1 answer
94 views

I have a AV2011 satcom antenna that has a Merrimac QHF-2-.312GN power divider/combiner that's good for 225mhz to 400mhz and I'd to replace it with a wider bandwidth version buuut this series doesn't ...
DisheveledDyke's user avatar
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3 votes
1 answer
171 views

Question: How can we measure the total losses due to reactive near-field interactions relatively simply, without far-field strength tests or mapping out the entire near field distribution? I've ...
Ryuji AB1WX's user avatar
  • 3,971
0 votes
1 answer
169 views

I'm looking for a fix to an airport radio communication issue. I have an all-metal hangar and have no communication with tower from inside it. One side of the hangar has line-of-sight with the tower ...
TonyH's user avatar
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2 votes
1 answer
217 views

Title sums the question up fairly well. I was recently testing two HTs and it was not until after keying a repeater with one that I thought about the fact that the other was sitting (turned on) only ...
MrRedacted's user avatar
  • 31
0 votes
4 answers
546 views

Is it possible to make an audio amplifier transmit radio signals when connected to its output with a ferrite coil or any other loop antenna and make the signal receive with another audio amplifier? I ...
Prabhat Karpe's user avatar
  • 75
2 votes
1 answer
271 views

How do small loopstick and short whip antennas work on the MW broadcast band? How do they perform and compare each other? Use reasonable and realistic physical parameters for a small pocket radio in ...
Ryuji AB1WX's user avatar
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1 vote
2 answers
291 views

I would like to know how a digital AM radio does the tuning without having any variable capacitor gang that is usually used in any analog radio circuit.
user avatar
0 votes
3 answers
407 views

I would like to know why most pocket radios come with a shorter whip antenna of about 20 cm, which is not a resonant one for FM or SW bands. So, how come they work like that?
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