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Evanescent Waveguide Filters - RF Cafe Forums

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 Post subject: Evanescent Waveguide Filters
Posted: Wed Nov 25, 2009 3:13 pm 

Joined: Wed Nov 25, 2009 3:06 pm
Posts: 1
I am attempting to design an evanescent waveguide filter in XBAND. The a dimension for my filter waveguide is 0.518'' and is based on the following paper:

"Evanescent Mode Compact Waveguide Filter" by Dr Qingyuan Wang

Anyone know how to transition into this filter? Any standard quarter wave transformer from say, WR112, will have to involve a section of waveguide in cutoff thereby contributing considerable loss/attn in the passband. I've tried just butting WR112 up against the filter for my HFSS or CST or WASPNET run but have difficulty reproducing the 20 dB return loss presented in the paper.

Any input appreciated.

Jason Wrigley

 Post subject: Re: Evanescent Waveguide Filters
Posted: Thu Nov 26, 2009 4:07 am 
User avatar

Joined: Fri Feb 17, 2006 12:07 pm
Posts: 268
Location: London UK
Hi Jason
George Craven was one of the pioneers of evanescent mode filters and other circuit elements realized in waveguide below cut-off. He therefore has left a legacy of very many papers and books on the topic, if you search on the IN for his name I am sure you will turn up a lot of data.
I found this, for example:

It discusses the equivalent circuit of the interface to an inductive section of evanescent waveguide.

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