# Parameters S12 Reverse transmission coefficient

1. ## Parameters S12 Reverse transmission coefficient

Hello everyone. Parameters S12 Reverse transmission coefficient, I would like a material that explains this subject. The materials that I find in the internet very weak. Because it simply says what it is and delivers a generic calculation, but does not explain what implies the quadripole applied to the antenna.
As far as I understand she somehow does the signal isolation.

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2. ## Re: Parameters S12 Reverse transmission coefficient

S12 has no dependency on antenna or other RF devices.S-parameters are definitions that relate interrelation of the Ports of a system either antenna or amplifier..
Can you post a sketch what you mean by ??

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3. ## Re: Parameters S12 Reverse transmission coefficient

Yes, that is true, but I used this as an example to simplify my doubt is related to microwaves. Here is the outline give example.

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4. ## Re: Parameters S12 Reverse transmission coefficient

Originally Posted by lufer17
Yes, that is true, but I used this as an example to simplify my doubt is related to microwaves. Here is the outline give example.
"Quadripole" means 2-Ports right ?? So, since the antenna has one port only, there won't be S12 or S21 etc.It will have S11 only and the quality of the antenna is defined S11 only by s-parameters.
If S11 is low as desired threshold, the antenna impedance is close to wanted. Antennas are checked also by EM Radiation Pattern , take it into account..

5. ## Re: Parameters S12 Reverse transmission coefficient

Maybe he talks about dual polarization antenna. Circular polarisation created by a power splitter with 90° phase delay.

6. ## Re: Parameters S12 Reverse transmission coefficient

S12 - Reverse Transmission (leakage or isolation or Insertion Loss....
I am referring to this item I did not understand the theoretical part and the practical part regarding the quadripole.

I can understand the parameter s11 on reflection coefficient and how it is calculated and its practice.

S12. I understood practically nothing.
Independent of the three figures and antennas that was put as an example

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7. ## Re: Parameters S12 Reverse transmission coefficient

Originally Posted by lufer17
S12 - Reverse Transmission (leakage or isolation or Insertion Loss....
S12. I understood practically nothing.
Imagine an amplifier..It has one input and one output port right ?? If you apply a signal to input port, you achieve amplified signal at the output.
But if you apply a signal to output port, you cannot obtain even applied signal level, even-more the signal will be attenuated.
Same analogy.. S12 is a Reverse Transmission Coefficient.A signal is applied to Port2 and someone observe the signal at Port1..

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