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  Topic: Acceptance test of antenna meas. system including chamber
gelunmak

Replies: 1
Views: 9281

PostForum: Questions Related to Antenna Theory   Posted: Fri Aug 06, 2010 6:43 am   Subject: Acceptance test of antenna meas. system including chamber
Hi everyone

Do you know are there any objective Acceptance-Test to verify an antenna measurement system is reliable?

e.g. isolation of the shield chamber > 110 dB, the aligment of the system, ...
  Topic: RF coil design
gelunmak

Replies: 3
Views: 16328

PostForum: Questions Related to Antenna Theory   Posted: Fri Jan 08, 2010 9:21 am   Subject: RF coil design
Actually, the simulations is very simple, i'm quite sure nothing screwed up because the simulated result are pretty much agree with experiment in term of the resonant frequency (S11 dip).

I maybe m ...
  Topic: RF coil design
gelunmak

Replies: 3
Views: 16328

PostForum: Questions Related to Antenna Theory   Posted: Tue Jan 05, 2010 9:42 am   Subject: RF coil design
hi everyone,

i'm doing some rf coil, with tuning capacitors, simulations using HFSS. The impedance bandwidth is very very narrow (S11), which is expected. I found that when i changed some minor v ...
  Topic: Near-field vs Far-field radiation pattern
gelunmak

Replies: 5
Views: 19770

PostForum: Questions Related to Antenna Theory   Posted: Mon Aug 24, 2009 9:42 am   Subject: Near-field vs Far-field radiation pattern
Hi All

As far as i know, the relationship between NearField Radiation Pattern and FarField Radiation Pattern is bounded by Fourier Transform.

i.e. NearField --> (FFT) ---> FarField

But ...
  Topic: Gain of a small Antenna
gelunmak

Replies: 6
Views: 17725

PostForum: Questions Related to Antenna Theory   Posted: Thu Aug 06, 2009 6:27 am   Subject: Gain of a small Antenna
Thanks for Admin's reply and i like the statement "gain should be measured as total gain unless specifically stated otherwise".

So for the case of circular polarization antenna, it's eith ...
  Topic: Antenna gain
gelunmak

Replies: 2
Views: 11684

PostForum: Questions Related to Antenna Theory   Posted: Wed Aug 05, 2009 8:55 am   Subject: Antenna gain
I've the same experience of having incorrect gain value when using some simulations software.

Of course, i tried to use a simple dipole to test the software but the value is higher than the expecte ...
  Topic: Gain of a small Antenna
gelunmak

Replies: 6
Views: 17725

PostForum: Questions Related to Antenna Theory   Posted: Wed Aug 05, 2009 8:37 am   Subject: Gain of a small Antenna
Yup, Efficiency is great. So we should target for high-efficiency small-antenna instead of high-gain small antenna (assuming we're targeting Omni-pattern, which is always true for small-antenna.)

...
  Topic: Gain of a small Antenna
gelunmak

Replies: 6
Views: 17725

PostForum: Questions Related to Antenna Theory   Posted: Tue Aug 04, 2009 6:20 am   Subject: Gain of a small Antenna
I pretty much understand the performance of such small antenna with multi-pol. And so i realize they are different from those standard-size or large antenna (like base station array) in term of gain. ...
  Topic: Gain of a small Antenna
gelunmak

Replies: 6
Views: 17725

PostForum: Questions Related to Antenna Theory   Posted: Mon Aug 03, 2009 9:12 am   Subject: Gain of a small Antenna
Let say i've a small antenna which usually is a multi-pol antenna with high cross-pol (i.e. say neither pure-vertical nor pure-horizontal pol.) across the bandwidth.

How would you describe the gain ...
  Topic: Achieve good return loss in low freq patch antenna?
gelunmak

Replies: 6
Views: 19617

PostForum: Questions Related to Antenna Theory   Posted: Wed Jul 29, 2009 8:32 am   Subject: L-probe antenna
Are you talking about L-probe feeding patch antenna? If yes, it's already a wideband design like using U-slot. Try to use air-substrate with thickness about 0.1 lambda.

Bty, so what is your bandw ...
  Topic: Antenna Quality Factor (Antenna-Q)
gelunmak

Replies: 1
Views: 16198

PostForum: Questions Related to Antenna Theory   Posted: Fri Jun 12, 2009 10:34 am   Subject: Antenna Quality Factor (Antenna-Q)
Is the Q-factor important in antenna theory?
What's is defination & equation of Antenna-Q?
Is it Q=fc/(f2-f1)? [fc-center freq, f1 and f2 are cutoff freq]

What i understand is higher the Q ...
  Topic: Transmitting and Receiving Antennas (CP, EP, LP)
gelunmak

Replies: 5
Views: 19610

PostForum: Questions Related to Antenna Theory   Posted: Fri Jun 12, 2009 2:37 am   Subject: I see. thks
So i'm using the IEEE definition. My way to memorize is to let the Thumb be Propagation Direction, and the 4 fingers will be the sense of rotation.

Anyway, thanks and it was a very good discussion ...
  Topic: Transmitting and Receiving Antennas (CP, EP, LP)
gelunmak

Replies: 5
Views: 19610

PostForum: Questions Related to Antenna Theory   Posted: Thu Jun 11, 2009 7:17 am   Subject: Thank you
Many thanks. Yup, Polarization Loss Factor is one of my interested toipc.

Yr explaination is clear for me, and so i was wrong in my guess in the question above. In case one, it's not 0.6667, it s ...
  Topic: Transmitting and Receiving Antennas (CP, EP, LP)
gelunmak

Replies: 5
Views: 19610

PostForum: Questions Related to Antenna Theory   Posted: Wed Jun 10, 2009 9:33 am   Subject: Corrections ...
I made a mistake on the vertival dipole transmitting 1W of power. The power will radiate in all directions, so i can't get back all power even when i use a vertical dipole.

So for the question, an ...
  Topic: Transmitting and Receiving Antennas (CP, EP, LP)
gelunmak

Replies: 5
Views: 19610

PostForum: Questions Related to Antenna Theory   Posted: Mon Jun 08, 2009 10:17 am   Subject: Transmitting and Receiving Antennas (CP, EP, LP)
Another question related to circular / elliptical polarization:

What i understand is if i've a Linearly Polarized Antenna, say a vertical dipole, transmitting 1W of signal. Theoretically, I can re ...
 
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