[Premium-Rx] Passive Filter Performance

[George Georgevits]

Hi All,

Thank you to everyone who responded.

I did some further thinking, assisted by the learned responses I received,
and have come to the following conclusions for the case of my band reject
passive filter:

1. All energy presented to the filter has to go somewhere
2. The filter (assuming it is made from ideal components) is made from L's
and C's, which only can store or pass energy, they cannot dissipate it
3. Therefore, the filter MUST reflect signals with frequencies in the reject
band
4. Hence it must present a low return loss (ie high SWR) across the reject
frequency band
5. Outside the reject band, it must present a high return loss, ie. it is a
good match
6. The only way to present a good match to the reject band signals is to use
a diplexer and route the reject band signals to a matched dummy load, where
they are dissipated without reflection

If I have missed something, please let me know.

Once again, thank you everyone.

George Georgevits
VK2KGG