145 MHz interference - the problem
The interference as seen on a nearby antenna - on two frequencies around 138
and 153 MHz, each containing multiple interfering frequencies!
The 138 MHz group:
The 153 MHz group:
145 MHz interference - a solution
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144 MHz |
<==> |
6-cavity
filter
used end-to-end |
<==> |
144MHz |
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| Antenna |
<==> |
Duplexer
e.g. MX-72N
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Duplexer |
<==> |
Radio |
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432 MHz |
<=== |
================= |
===> |
432 MHz |
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Filter response end-to-end - rejection notches
Filter response - passband loss
At least I learnt a little more about the facilities in the RIGOL
DSA815/TG spectrum analyser! | 
