How to measure Bandwidth and Q of high-pass T-match circuit?

[VINAY_RAO]

Hello all,

Here I attached the circuit and dB plots of its S11, S21 and ZM1. I designed this circuit for fr (center freq/resonating freq) =2.4GHz and Q = 5. From theoretical concept, I am calculating Bandwidth as
B.W = (fr/Q) = 480MHz.
How can I measure simulated Bandwidth and Q from the plot which I attached for the given T-match circuit?






Regards,
Vinay Rao.

 

[capcas]

I dont know why are you measuring the BW from Q. Usually we measure BW from S21 and then calculate the Q of the circuit. Your filter seems to be high pass filter and high pass filter usually have cut off frequency rather than of BW.

 

[VINAY_RAO]

Hello capcas,
Thanks for your reply. Yes it is high pass filter. What i defined "B.W = (fr/Q)" is one of the definition of Q. I designed this circuit for Q=5. How can i measure resulted Q from the simulation plot? For high pass, i have to measure cut-off frequency and then i got to find out 'Q' you mean?

 

[capcas]

Usually for high pass and low pass filter you measure Q by the rejection it provides, please look at Microwave Engineering by Pozar. In this circuit you are getting almost infinite Q because of ideal nature of selected elements.