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Old October 4th 05, 08:20 AM
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Default Connecting several bandpass filters.

Hi

I have come up with one of those crazy DYI ideas which I would like to try
to implement but one thing still remains.

I have two UHF (TV) arial pointing in different directions and would like to
connect them together through BP filters to minimize noise.
BP = Bandpass
Antenna 1: UHF channel (Europe) BP 1 ch 22-37, BP 2 ch40 -44, BP 3 ch 49 -
68/ or high pass
Antenna 2: UHF channel (Europe) BP 1 ch 21 / or low pass, BP 2 ch38 -39, BP
3 ch 47

I have found formulas to design each section of BF but how to you connect
several BP filters in parallel??? I have investigated some old TV filter and
they have a coil (12 WDG) in and out of each BP section but is that the way
to do it and how does it influence the design of each BP.

The only approach that I can find is to split the signal into three (- 6dB )
then feed each into a BP filter and the Combine them again (-6dB). This will
result in each BP section seeing 75 Ohms as they shouland they would not
interfere with eachother. Ofcouse i would need a 20 dB amplifier to fix the
loss.

But is there a better way.

Best regards

Svend Holby