HB VHF low-pass filter
K7ITM wrote:
I question the bit about insertion loss 7MHz away being a non-issue
with only a single open stub across the line. If you put an open stub
of lossless 50 ohm line a quarter-wave long at 153MHz across the feed
line, it puts a short across the line at 153, but it puts 0.26-j3.58
ohms across it at 146MHz. That's a 99% reflection, or SWR close to
200:1 at 146. It's only about a 17dB loss, but that's more loss than
I'd want.
You're correct. Someone pointed this out to me via email so I'll
retract my recommendation of using the stub.
Thanks,
Bill
|