Transmitted Power of a waveguide using CST

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Ashubhu

Joined: 20 Sep 2008
Posts: 49
Helped: 10
Location: INDIA

29 Apr 2009 10:56 change port power

Hi everybody
i am analyzing Cylindrical waveguide using CST Microwave studio. I want to calculate Total Power transmitted and Power loss for a cylindrical waveguide using CST but I am not understanding hw can i calculate it? Plz help me.

Thanks

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mauloftin

Joined: 29 Oct 2008
Posts: 262
Helped: 22
Location: CZ

29 Apr 2009 11:18 s11 input power loss formula

Ashubhu wrote:

Hi,

I do not know, where is problem exactly, but you have cylindrical waveguide - so you have one port on the one side and second port on the second side - after calculate, you have S21, S11, S12 and S22 (S21=S12 and S11 = S22). This is your transmitted and return loss.

But if you have cylindrical waveguide for your for your frequency (so that mean correct diameter), S21 = 0 dB and S11= - ∞ dB (exactly about -50 - -60 or -100 dB).

Can you give me more specification of your problem ?

Ashubhu

Joined: 20 Sep 2008
Posts: 49
Helped: 10
Location: INDIA

29 Apr 2009 15:55 cst problem s21

Hi, thanks for your reply
i have considering Cylindrical waveguide exactly. For this, i want the total power transmitted(Pt) and power loss(PL) calculation as you can see in Liao's Book. These i want to calculate using CST. Power transmitted and power loss with modewise is also of the intrest. So you plz help me hw can i calculate using CST. S-parameter we have found but Power transmitted and power loss are different from that.

Thanks

Kezman

Joined: 05 Jul 2006
Posts: 62

29 Apr 2009 17:37 transmitted power loss

The power will be reflected, transmitted and loss.
1-S11*S11 represent the power except reflection loss. If waveguide does no has loss, S21*S21=1-S11*S11. However, practical waveguide has loss, 1-S11*S11-S21*S21 represent transmission loss

Ashubhu

Joined: 20 Sep 2008
Posts: 49
Helped: 10
Location: INDIA

30 Apr 2009 4:23 change waveguide port power in cst

Kezman wrote:

Very-very thanks Kezman, I highly appreciate your suggestion. Really this will help me for solving my problem.
One more thing i wanted to know. S11 and S21(S-parameters) in CST is obtained with mode-wise. So the power Transmitted and power loss will be for the related mode. Wheathe or not, we can obtained the Total Power transmitted and Total Power loss???
One more thing ,Can we change input exciting signal power to any value in CST?

Kezman

Joined: 05 Jul 2006
Posts: 62

02 May 2009 17:54 power transmitted in waveguide

The same to it!
You can simulate any mode in CST, but practically, the loss lie on the mode which you inspirit on the input port.

You need not to change power on port, because S-Parameter is the proportion of power in CST. If you want to get loss about the power, you can calculate: Transmitted Power (dBm)=Input Power(dBm)-|S21|(dB). If you want to get loss about Watt, you can Input Power(Watt)-Transmitted Power (Watt)