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  Topic: Impedance transition from antenna to free space
helix

Replies: 2
Views: 4016

PostForum: Questions Related to Antenna Theory   Posted: Tue Dec 06, 2016 6:42 pm   Subject: Impedance transition from antenna to free space
Powewave -- consider the difference between intrinsic impedance and characteristic impedance and this should resolve the apparent paradox.
  Topic: About antenna noise temperature
helix

Replies: 1
Views: 4658

PostForum: Questions Related to Antenna Theory   Posted: Sun Jul 31, 2016 3:56 pm   Subject: About antenna noise temperature
Antenna noise temperature is not necessarily correlated directly to a physical temperature but it's merely a way to express the noise power received by an antenna...

Probably what you want to kno ...
  Topic: Inconsistent SWR readings using a Buddipole Antenna 40&2
helix

Replies: 1
Views: 4704

PostForum: Questions Related to Antenna Theory   Posted: Mon Jul 18, 2016 10:56 pm   Subject: Inconsistent SWR readings using a Buddipole Antenna 40&2
What do you mean when you say you make measurements both inside and outside the shack.

One thing, you report different VSWR readings at different power levels. That shoukdn't ordinarily happen, ...
  Topic: Isotropic antenna with 100 kHz- 6GHz BP
helix

Replies: 6
Views: 7395

PostForum: Questions Related to Antenna Theory   Posted: Thu Jul 14, 2016 12:51 am   Subject: Isotropic antenna with 100 kHz- 6GHz BP
http://www.comsistel.com/HAM%20documents/kanda2.pdf

Is a good start.
  Topic: FM Radio Reception by the Human Brain/Head
helix

Replies: 10
Views: 10611

PostForum: Questions Related to Antenna Theory   Posted: Wed Jul 13, 2016 3:05 am   Subject: FM Radio Reception by the Human Brain/Head
The microwave auditory effect, which does NOT refer to perception of intelligible speech, but merely any sound, is reported in legitimate scientific literature:

https://scholar.google.com/scholar?q ...
  Topic: FM Radio Reception by the Human Brain/Head
helix

Replies: 10
Views: 10611

PostForum: Questions Related to Antenna Theory   Posted: Tue Jul 12, 2016 2:19 pm   Subject: FM Radio Reception by the Human Brain/Head
Interesting. RF propagation is very complicated and depends greatly on the frequency.... it's hard to make general statements. However given the signal strength required for the microwave auditory ...
  Topic: FM Radio Reception by the Human Brain/Head
helix

Replies: 10
Views: 10611

PostForum: Questions Related to Antenna Theory   Posted: Tue Jul 12, 2016 2:17 am   Subject: FM Radio Reception by the Human Brain/Head
It is indeed possible for RF to be "heard"

https://en.m.wikipedia.org/wiki/Microwave_auditory_effect


However 1) this happens mostly at relatively high power levels (do you live nea ...
  Topic: Isotropic antenna with 100 kHz- 6GHz BP
helix

Replies: 6
Views: 7395

PostForum: Questions Related to Antenna Theory   Posted: Tue Jul 12, 2016 2:01 am   Subject: Isotropic antenna with 100 kHz- 6GHz BP
It is possible, the constraint is how much sensitivity do you need.

In fact a quick search showed a product like this already exists.


http://www.arww-rfmicro.com/html/18200.asp?id=1124
  Topic: Passive antenna for off grid cell reception
helix

Replies: 2
Views: 6251

PostForum: Questions Related to Antenna Theory   Posted: Sat Jun 25, 2016 3:47 pm   Subject: Passive antenna for off grid cell reception
This is a very interesting question. How far is your camp from the nearest cell tower?
  Topic: Slits Method
helix

Replies: 1
Views: 5483

PostForum: Questions Related to Antenna Theory   Posted: Fri Jun 17, 2016 12:08 am   Subject: Slits Method
The slots must be transverse to the current flow in order to have any appreciable effect. That is, they must force current to "reroute"around the slot. Since the current is zero at the rad ...
  Topic: 2D pattern in slot antenna by HFSS got problems
helix

Replies: 1
Views: 5530

PostForum: Questions Related to Antenna Theory   Posted: Thu Jun 16, 2016 4:21 am   Subject: 2D pattern in slot antenna by HFSS got problems
I think some of your trouble has to do with the coordinate system you're calculating far fields in. It's easiest if you define a new coordinate system for the far field calculation whose z axis is al ...
  Topic: running multiple FEKO simulations in a row
helix

Replies: 2
Views: 7068

PostForum: Questions Related to Antenna Theory   Posted: Sat May 21, 2016 2:54 am   Subject: running multiple FEKO simulations in a row
You can download a lua script from the official feko site that steps a parameter in cadfeko and will also load all the solutions in postfeko. At least you could fit the previous version (7, I think). ...
  Topic: Oxidation on Loop Receive Antenna
helix

Replies: 2
Views: 6721

PostForum: Questions Related to Antenna Theory   Posted: Mon Apr 11, 2016 1:41 pm   Subject: Oxidation on Loop Receive Antenna
Aluminum oxide, also known as alumina, is an incredible insulator and low loss dielectric. But a thin surface layer should not have much effect on your loop.
  Topic: Averaging during calibration
helix

Replies: 3
Views: 6244

PostForum: Questions Related to Antenna Theory   Posted: Fri Mar 18, 2016 5:20 am   Subject: Averaging during calibration
eCal generally produces less accurate calibrations than mechanical standards that are within spec (ie, not damaged).

I suggest looking into ways to verify your calibration (I'm sure there are many) ...
  Topic: Far-Field Question
helix

Replies: 4
Views: 7570

PostForum: Questions Related to Antenna Theory   Posted: Wed Mar 09, 2016 3:57 pm   Subject: Far-Field Question
Nothing "magic" happens suddenly when you cross d^2/lambda. Look up how it's derived... It has to do with phase front curvature (deviation from plane wave) from an aperture (which you don' ...
 
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