Re: 13cms bandpass filter

John Lemay


Many thanks, that off-air plot is very helpful.

The close proximity of 2350MHz to our usual working frequencies is a bit of
a challenge, but I'll see what comes of a practical test.


John G4ZTR

-----Original Message-----
From: [] On Behalf Of
Brian Howie GM4DIJ
Sent: 05 June 2022 09:16
Subject: Re: [UKMicrowaves] 13cms bandpass filter

In message <002d01d87849$94c84c10$be58e430$>, John Lemay
<john@...> writes
'Evening all

I've been busy in the workshop producing swarf. Sadly, I've not found a
buyer yet.....

However, as a by-product, I've been developing a narrow band 13cms
filter, because my low loss, wideband interdigital filter may not have
enough (or
any) attenuation against close-in cellular signals.

A plot of the latest filter is attached.

What I would like to know, is just what frequencies are in use for
mobile phones, which are close to 2320MHz ? I've accessed information
on frequency allocations - but what is happening in practice ?

If anyone here would like to provide a practical test, please get in
contact off reflector and I'll be pleased to loan this prototype.


John G4ZTR
It was the stuff starting at 2350 that was giving me grief. I'm 500m
from a major telecoms mast. A single cavity filter fixed it. It was a
bit lossy , but I could put it after the preamp. There was a discussion
earlier in the year.


Brian GM4DIJ

Brian Howie

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