[Premium-Rx] Insertion Loss and Return Loss of Passive Filters

[James A. (Andy) Moorer]

Unless the filter has been specifically designed to do so, the return loss 
will be unrelated to the insertion loss. We are taught to design for one 
specific feature of the filter, like insertion loss, and to leave the others 
"uncontrolled" - they just turn out however they turn out. Your filter 
sounds pretty typical to me.

You can design a filter that will have a given return loss as well as a 
given insertion loss, but it would be at least twice as complex as just 
designing for insertion loss.

James A. (Andy) Moorer
www.jamminpower.com


----- Original Message ----- 
>
> So my question is this - has this filter been poorly designed, despite the
> fact that the insertion loss criteria are completely satisfied? Or another
> way to put this question is - should the filter also have a good return 
> loss
> performance (ie. be a good match to 50 ohms) over the entire band of
> operation, whilst maintaining its band rejection performance requirements,
> in order to be considered as correctly designed?
>