Mr. Rabie

In CST MWS  (and I guess in other tools too) you cannot add an imaginary part to the discrete port. What you can do, simulate it on MWS with 50 Ohms discrete port, get the antenna impedance (which by the way do not depend on the discrete port impedance, it just operates a normalization on the signals) and later when done the 3D simulation open the project in Design Studio, the circuit simulator of CST. There you'll see your antenna represented as a small box (containing the just simulated S parameters) and then you may attach a port whose impedance is complex. 

You can get it simulated under Design Studio with complex impedance and even see the Far/Near Field results updated in MWS (the 3D solver), just need to check on the "combine results" option under the Transient Task.

good luck,

marcelo

Mr. Rabie

In CST MWS  (and I guess in other tools too) you cannot add an imaginary part to the discrete port. What you can do, simulate it on MWS with 50 Ohms discrete port, get the antenna impedance (which by the way do not depend on the discrete port impedance, it just operates a normalization on the signals) and later when done the 3D simulation open the project in Design Studio, the circuit simulator of CST. There you'll see your antenna represented as a small box (containing the just simulated S parameters) and then you may attach a port whose impedance is complex. 

You can get it simulated under Design Studio with complex impedance and even see the Far/Near Field results updated in MWS (the 3D solver), just need to check on the "combine results" option under the Transient Task.

good luck,

marcelo

Hi!

In the case of discrete port: Define a discrete port impedance directly in port setting (only real valued impedance is support). In the case of waveguide port: Waveguide port generaly needs some homegeneous space in front.

As I did in HFSS, I'd got directly real and imaginary part of impedance on separate graphs w.r.t. frequency, and that can be plotted on the same graph further.

As Dr. perotoni is saying that's perfectly correct. Initially, you'll have to take 50 ohm.

That you can do on ADS.

Discrete ports are mainly used to simulate lumped element sources inside the calculation domain. These ports are a good approximation for the source in the feeding point of antennas when calculating farfields. In some cases, these ports may also be used to terminate coaxial cables or microstrip lines.

Thanks,

All The Best!

you can simulate the antenna with discrete port with Zo=50 ohm

then you can export the input impedance (real and imaginary)

and by using matlab program, all the RFID tag parameters can be calculated through simple program

reflection coefficient, transmission coefficient and read range

Hi all, 

I designed a small dipole antenna (lamda/15), so that the input impedance of the antenna is complex (real and imaginary). i did matching network in Design Studio  and I got the good S11but when I did  this in CST MWS  with using the same matching circuit (one L parallels and one L series) , I got very bad S11less than -6 dB ONLY ) 

What I can do ....please help me 

Hi Maged

If I understood correctly theres something wrong - the antenna's S11 has to be the same in both MWS and DS (DS takes the results from MWS). Maybe your L and C are not the same, or the port in DS is not set at 50 Ohms (fixed with a right click on it).

Hi Marcelo, 

Thank you. 

I am sure about the values of  lumped element  and the impedance of DS port.

Maybe something about the connected.... please see the attached  

Hi Maged

I guess I know whats may be going on... A discrete port is a perfect balanced excitation. From your figure one lumped element is in series with the generator; the other blue lumped device is shunting both generator and lumped element. Is it what you got in DS?

Hi Marcelo, 

Yes, one lumped element as a series inductance (Ls)  with DS port and other as a parallel inductance . I got s11 equal -6  dB at 600 MHz, 

Hello Mr. Rabie,

Did you get that? Could you share whit me?

Thanks a lot

Hi Maged and Dr Perotoni,

I am facing problem for excitation of Split Ring Resonator. The design figure is attached below. kindly, tell me that how can I design lumped element in parallel with DS in CST. And what value of lumped element assigned in CST.

Thanks

dear Maged Aldhaeebi can you tell me that how you placed lumped element in series with discrete port. As you upload pic above.

thank you.