I am new to filter design. I am following the book "Microstrip filters for RF/microwave applications" 2nd edition by Jia-sheng Hong. I tried to reproduce the simulated resonant response of S21 to find the two peaks. (one example from the book is attached as fig1.) You can see that the two peaks are always hitting 0dB. But in my simulation, the peaks are distinct but not 0dB, it is < -40dB, No matter I use calibration as None or TML with reference offset. Can someone help me how to get the peaks to resemble the book (with the peak value of 0dB)?
I am using microstrip filter. All the conductors and vias and substrates are lossless. Also, S11(Not shown) is ~0dB
Thanks very much!