Two Antennas transfer functions

Hello all,

I read a paper talking about the transfer function calculation for an antenna link. So that we can obtain the S21 (magnitude AND phase) for two antennas. This was based on the measurement of what is called transmitting transfer function and receiving tranfer function. Does anybody have any information about this topic or have any resources about it ? any help will be appreciated.

thank you very much,
Adel

Hi, Adel:

If you know the Tx antenna's radiation patterns and the Rx antenna's port voltage and current with given plane-wave excitation, you can find it the Tx/Rx transfer function. This can be done on PatternView of IE3D. It is possible you can find similar functionalities from other packages.

Best regards,

Thank you very much Mr. Jian. But I heard that only one simulation run can be used based on a reciprocity theorem of the antenna. To obtain the Rx transfer function you just need to multiply the Tx transfer function by C0/(i*w). but I didn't find any one using this method.

Hi, adel_48:

You are right. One simulation of BOTH ANTENNAS is enough. However, when the Tx and Rx antennas are far away, it is better not to simulate BOTH ANTENNAS simultaneously. Instead, we should simulate the Tx antenna and Rx antenna separately. We just need their radiation patterns to find the the Tx and Rx transfer function. What I suggested is basic based upon this idea. We are simulating each antenna separately. You can consider it as ONE SIMULATION becase each antenna is not simulated twice.

I am not quite sure what you mean Tx transfer function and Rx transfer function. If you get the S21, it is already the transfer function in s-parameters form. Regards.

Hello Mr. Jian.

Yes, the transfer function of the two antennas is the S21. But some people use what is called Tx & Rx transfer function. And using both we can get S21 as S21 = Htx * Hrx * exp(-i*k*r)/(4*pi*r). They get the Htx as a relation between the transmitted fields and the terminal voltage of the transmitting antenna. And the receiving transfer function as the relation between the incident fields and the terminal voltage at the receiving antenna.

Actually I have another question. Do you think that if the two antennas are far apart such that coupling is small enough, we can simulate the Tx antenna. Get the fields. and then use them as the excitation of the Rx antenna. In this case, I am doing the simulation two times but for the smaller problem. Since the plane wave approximation might not be very accurate if the two antennas are not really far apart ?

Thank you Mr. Jian and best regards,
Adel

Hi, Adel_48:

I think we are talking about the same thing. Basically, we want to find 2 things:

1. Tx antenna's radiation pattern. That is basically the Tx transfer function in your discussion.

2. The relationship between the Rx voltage and the planewave incident filed intensity. This is what you call the Rx transfer function.

On IE3D's Tx and Rx transfer function, we are basically solving the same thing you are discussing even though we did not explicitly provide the terms for Tx transfer function, Rx transfer function and the other term. Thanks!

Best regards,

try XGDTD s/w