Waveguide is a broadband bandpass filter. You can couple one size to
another as long as there is overlap in the pass band. Go to low in
frequency and the waveguide just blocks the signal. The cut off frequency.
It is not a brick wall filter. Normally the cut off frequency is something
like the 1 dB mismatch loss frequency, go lower and the loss goes up
quickly.
Different problem in going too high.
To use my photon analogy:
Photons simply will not fit down the tube if they are too large (low
frequency). Go too high in frequency and you get other than single file
photons trying to get town the tube. Like two abreast, two rows two columns
etc etc.
Those are called higher order modes and you can use them if you take care of
launching and receiving the signal in a low loss high return loss manner.
http://www.rfcafe.com/references/electrical/waveguide-chart.htm
Then there are the non rectangular waveguides. Ridge waveguide is
physically smaller than rectangular waveguide. Circular is good for dual
pol and is exceedingly low loss but extra care has to be taken to prevent
polarization rotation.
-----Original Message-----
From: cstanners--- via Af
Sent: Saturday, September 20, 2014 6:41 PM
To: Jason McKemie via Af
Subject: [AFMUG] Waveguide compatibility info?
Does anyone have resources/FAQs/etc to understand Waveguide compatibility?
