Re: WG20 Round flange

Christopher Bartram <cbartram@...>

Hello John

The answer is that _if_ you can calibrate the length of transmission-line as an attenuator, eg. by using a stable, well matched source and a VSWR indicator like the HP415, and confirm that it's well matched, then it would make a perfectly usable, albeit frequency-dependent, attenuator. The phase response might be also be a problem in some applications ...

If you were starting from scratch, measuring the return-loss might be difficult problem to solve, as good coaxial components such as directional couplers at frequencies above 18GHz (where conventional SMA connectors run out of steam), are difficult or expensive to buy. Waveguide components are much easier to find, and work better than coaxial/planar ones at 24GHz and up.

Transmission-lines, such as a waveguide operating below its cut-off frequency, have been, and I think still are, used as attenuation standards, as it's possible to directly relate the physical dimensions to attenuation.

Vy 73


Christopher Bartram MIET
Christopher Bartram RF Design
Llygad yr Haul
Powys SY17 5LE

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