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  Topic: Grid Antenna Maximum Wire Separation
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Replies: 2
Views: 131

PostForum: Questions Related to Antenna Theory   Posted: Tue Jun 19, 2018 12:11 am   Subject: Grid Antenna Maximum Wire Separation
Do you have a picture?

If you are using a wire mesh reflector at 5.8GHz, then the same reflector should be fine for all lower frequencies (since the separation in wavelengths will be less).

Idea ...
  Topic: resonat
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Replies: 1
Views: 243

PostForum: Questions Related to Antenna Theory   Posted: Thu May 24, 2018 7:47 pm   Subject: resonat
Typically that means the antenna radiates efficiency at that frequency. So most of the power delivered to the antenna is radiated away instead of reflected or absorbed.

Antenna impedance usually h ...
  Topic: Need magnetic loop antenna theory references.
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Replies: 3
Views: 425

PostForum: Questions Related to Antenna Theory   Posted: Thu May 10, 2018 11:27 pm   Subject: Need magnetic loop antenna theory references.
What specifically are you looking for?

Magnetic dipoles are typically loop antenna that are much smaller than a wavelength. They are inefficient and horizontally polarized. Basically their fields ...
  Topic: Radio telescopes and sensitivity
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Replies: 1
Views: 385

PostForum: Questions Related to Antenna Theory   Posted: Wed May 02, 2018 5:06 pm   Subject: Radio telescopes and sensitivity
See Antenna Temperature:
http://www.antenna-theory.com/basics/temperature.php

The noise is receives is proportional to the temperature the antennas "sees". So if deep space, use ~4K
  Topic: does the measured power actually leave the antenna?
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Replies: 2
Views: 521

PostForum: Questions Related to Antenna Theory   Posted: Mon Apr 16, 2018 6:29 pm   Subject: does the measured power actually leave the antenna?
If your antenna has VSWR of 1.4, then yes, 97.2% is delivered to the antenna.

How much is radiated depends on your antenna efficiency: http://www.antenna-theory.com/basics/efficiency.php

Many ...
  Topic: pigtail-pipe (dipole) antenna for wifi
admin

Replies: 1
Views: 785

PostForum: Questions Related to Antenna Theory   Posted: Sun Apr 01, 2018 8:42 pm   Subject: pigtail-pipe (dipole) antenna for wifi
The target length for a very thin wifi dipole antenna is about 0.49lambda, or 61mm. This means each arm is about 30mm. Two things reduce the correct length:

- The fatter you make the arms, the wi ...
  Topic: Reduce chance of TVI
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Replies: 1
Views: 799

PostForum: Questions Related to Antenna Theory   Posted: Sun Mar 18, 2018 3:26 am   Subject: Reduce chance of TVI
I don't think it should matter, those antennas pointed at your garden are receive only antennas
  Topic: antenna Q factor is low
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Replies: 2
Views: 1153

PostForum: Questions Related to Antenna Theory   Posted: Tue Mar 06, 2018 8:55 pm   Subject: antenna Q factor is low
If your Q is low, you need to find the loss or maximize inductance

tightly couple your loops, improves your inductance faster than the resistance goes up
if you are backed by metal, you need ferri ...
  Topic: Far field in arrays
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Replies: 4
Views: 2361

PostForum: Questions Related to Antenna Theory   Posted: Wed Dec 27, 2017 11:46 pm   Subject: Far field in arrays
You didn't ask if it is impossible to use an array under the far field distance, you asked what conditions are required such that the far field approximations are accurate
  Topic: Far field in arrays
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Replies: 4
Views: 2361

PostForum: Questions Related to Antenna Theory   Posted: Wed Dec 27, 2017 5:22 pm   Subject: Far field in arrays
The entire array. If you have a large array and aren't far away relative to the size of the array then the angle of arrival for each antenna will be different, so you can't use the traditional beamst ...
  Topic: How can you disable antenna that the Xbox One controller use
admin

Replies: 1
Views: 1971

PostForum: Questions Related to Antenna Theory   Posted: Mon Nov 27, 2017 9:53 pm   Subject: How can you disable antenna that the Xbox One controller use
Yes, you found the antenna. Looks to me to be a modified pifa antenna, a bit different than an IFA, but they are somewhat similar anyway: http://www.antenna-theory.com/antennas/patches/pifa.php

...
  Topic: RFID Antenna complex impedance calculation
admin

Replies: 3
Views: 3340

PostForum: Questions Related to Antenna Theory   Posted: Mon Sep 25, 2017 5:07 pm   Subject: RFID Antenna complex impedance calculation
Makes no sense. Measure the antenna with a single port and you can get the impedance directly.
  Topic: RFID Antenna complex impedance calculation
admin

Replies: 3
Views: 3340

PostForum: Questions Related to Antenna Theory   Posted: Fri Sep 22, 2017 5:32 pm   Subject: RFID Antenna complex impedance calculation
First question: Why are there 2 ports in your measurement? Antenna is a 1 port device.
  Topic: Artifact: is it an antenna?
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Replies: 3
Views: 3529

PostForum: Questions Related to Antenna Theory   Posted: Tue Sep 19, 2017 9:25 pm   Subject: Artifact: is it an antenna?
Yeah that is a PIFA antenna [http://www.antenna-theory.com/antennas/patches/pifa.php]

Basically, the lowest frequency of operation is about a quarter wavelength for the length of the arm. The arm ...
  Topic: Artifact: is it an antenna?
admin

Replies: 3
Views: 3529

PostForum: Questions Related to Antenna Theory   Posted: Mon Sep 18, 2017 6:17 pm   Subject: Artifact: is it an antenna?
That does look like an IFA or PIFA antenna, modified for some reason (additional bandwidth? lower operating frequency?) From the size, I'd estimate somewhere in the 75-300Mhz region.

The back si ...
 
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