Effect of Q-Factor on filter performance

Hi,

I understand that for inductors the higher the Q-factor the lesser the loss, but may i know for a bandpass filter, other than affecting the insertion loss what other effect does the overall Q of the bandpass filter have on the circuit.

Thank you
Wancai

Look at the book "HF Filter Design and Computer Simulation",Randall W. Rhea
1994.

Effect of elements low Q is illustrated on picture. Thin yellow curves are for lossless elements filter.

From what i understand, the higher the Q, the edge of the bandpass will be more squarish whereas for lower Q, the edge of the bandpass is very roundish. And it seem that if i increase the thickness of the substrate, the Q tends to improve.

But i like to know is that any software that is able to calculate the Q of the tranmission line? I think genesys can do it, but i can't seem to recall how issit been done? Thanks.

Rogers Corp. has a free downloadable program called mwi.exe that can calculate losses of transmission lines. This is only the resistance and dielectric hysteresis losses. It does not calculate the radiation loss.

Here is an example of Genesys Tline module calculation of microstrip line parameter, including unloaded Q

thanks ,it's very useful~~

me too,it's very useful

As for band pass filter the width of central lobe (for amplitude to vary b/w h0/√2)
is w0/Q , so higher the value of Q sharper will be the response around w0 and hence in general better response

lerning...