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  Topic: How can I measure antenna input power?
R. Fry

Replies: 6
Views: 1577

PostForum: Questions Related to Antenna Theory   Posted: Wed May 23, 2018 10:18 am   Subject: Re: power at the antenna, will this approach work?
I do not have a way to obtain some of the parameters mentioned in the reply. ... I hope this would lump all the mentioned parameters and represent the desired real power input to the antenna. How much ...
  Topic: How can I measure antenna input power?
R. Fry

Replies: 6
Views: 1577

PostForum: Questions Related to Antenna Theory   Posted: Tue May 22, 2018 11:36 am   Subject: Re: How can I measure antenna input power?
I would like to measure the power entering/leaving my antenna, at the antenna. ...
Power entering antenna system = IČR

where
I = r-f current across antenna system feedpoint terminals
R = the re ...
  Topic: Need magnetic loop antenna theory references.
R. Fry

Replies: 3
Views: 849

PostForum: Questions Related to Antenna Theory   Posted: Tue May 22, 2018 10:27 am   Subject: Need magnetic loop antenna theory references.
Just to note that the electric and magnetic radiation existing in the far field of a transmit antenna always have the same relationship to each other -- regardless of the antenna configuration that p ...
  Topic: free space impedence matching?
R. Fry

Replies: 8
Views: 15944

PostForum: Questions Related to Antenna Theory   Posted: Fri Feb 16, 2018 12:45 pm   Subject: Radiation Resistance
Radiation resistance is the result of an antenna acting to radiate e-m energy into space. It occurs whenever r-f current can be made to flow along the conductor(s) of an antenna.

Radiation resista ...
  Topic: Far Field radiation and Non Resonant Antennas
R. Fry

Replies: 11
Views: 17002

PostForum: Questions Related to Antenna Theory   Posted: Wed Jun 08, 2016 1:37 pm   Subject: An Elaboration on the Comments of G3TXQ:
For consideration/discussion, below are some clips on this topic from https://en.wikipedia.org/wiki/Electromagnetic_radiation . The bold font attribute was added to call attention to important points ...
  Topic: Far Field radiation and Non Resonant Antennas
R. Fry

Replies: 11
Views: 17002

PostForum: Questions Related to Antenna Theory   Posted: Mon Jun 06, 2016 1:20 pm   Subject: Re: Reference Books
... My thesis is that reactance does not radiate.
Agreed.

... If your disagreement is with a reference, kindly dispute with the author, I am not qualified to defend their work.
I have been agree ...
  Topic: Far Field radiation and Non Resonant Antennas
R. Fry

Replies: 11
Views: 17002

PostForum: Questions Related to Antenna Theory   Posted: Sun Jun 05, 2016 10:52 pm   Subject: Re: Electromagnetic Compatibility: Principles and Applicatio
... The radiation resistance is defined as that part of the antenna that contributes to the power radiated by an antenna. ... For an electrically small dipole or monopole antenna, where l, which is ...
  Topic: Far Field radiation and Non Resonant Antennas
R. Fry

Replies: 11
Views: 17002

PostForum: Questions Related to Antenna Theory   Posted: Sun Jun 05, 2016 11:20 am   Subject: Far Field radiation and Non Resonant Antennas
Properly matching the feedpoint Z of a non-resonant antenna to the transmission line connected there means that the r-f current and voltage at the feedpoint are in phase.

Other things equal, both t ...
  Topic: Farfield calculation for a scattering object
R. Fry

Replies: 1
Views: 7042

PostForum: Questions Related to Antenna Theory   Posted: Wed Jun 10, 2015 10:42 am   Subject: Farfield calculation for a scattering object
Depending on how accurately you construct the physical model of this situation, NEC (Numerical Electromagnetics Code) can produce good insight toward answering your questions.

In general, VHF/UHF s ...
  Topic: Dipole antenna characterization
R. Fry

Replies: 3
Views: 9499

PostForum: Questions Related to Antenna Theory   Posted: Wed Mar 11, 2015 10:33 am   Subject: Dipole antenna characterization
The inner surface of the outer conductor of a coaxial cable carries the same r-f current magnitude as the outer surface of the inner conductor, just 180 degrees out of phase with it.

When a coaxial ...
  Topic: Why does an antenna work even though only 1 end connects?
R. Fry

Replies: 9
Views: 18533

PostForum: Questions Related to Antenna Theory   Posted: Sun Feb 08, 2015 1:53 pm   Subject: Why does an antenna work even though only 1 end connects?
Maybe another person will respond to your questions better than I did.

I do suggest that you study antenna engineering texts and other areas of antenna-theory.com, where many of your answers can be ...
  Topic: Why does an antenna work even though only 1 end connects?
R. Fry

Replies: 9
Views: 18533

PostForum: Questions Related to Antenna Theory   Posted: Sun Feb 08, 2015 12:29 pm   Subject: Why does an antenna work even though only 1 end connects?
"current"... This means "electrons flowing", doesn't it?
Yes

"r-f current" ... This is still electrons flowing somewhere, isn't it?
Yes

"2nd conductor" ...
  Topic: Why does an antenna work even though only 1 end connects?
R. Fry

Replies: 9
Views: 18533

PostForum: Questions Related to Antenna Theory   Posted: Sun Feb 08, 2015 10:09 am   Subject: Re: Open ended
...Take for example my 27mhz radio-controlled car transmitter, and the corresponding receiver: both of those antennas are literally bits of wire soldered onto the circuitboard at only 1 end. What ma ...
  Topic: Why does an antenna work even though only 1 end connects?
R. Fry

Replies: 9
Views: 18533

PostForum: Questions Related to Antenna Theory   Posted: Sat Feb 07, 2015 1:01 pm   Subject: Re: Electro MAGNETIC - is that the clue?
...Is this in fact what's going on?...
The schematic included in the OP does not show how those components are constructed.

The antenna shown there radiates because (typically in the VHF spectrum) ...
  Topic: Feeder SWR & power loss
R. Fry

Replies: 22
Views: 48502

PostForum: Questions Related to Antenna Theory   Posted: Sat Jul 26, 2014 11:22 am   Subject: Feeder SWR & power loss
... 50 ohm receiver powers a 50 ohm load...
For some additional input -- I have taken part in factory tests of
high-power Class C single-tube/tuned cavity FM broadcast transmitters
driving 50-ohm t ...
 
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