Evanescent Waveguide Filters - RF Cafe Forums

RF Cafe Forums closed its virtual doors in late 2012 mainly due to other social media platforms dominating public commenting venues. RF Cafe Forums began sometime around August of 2003 and was quite well-attended for many years. By 2012, Facebook and Twitter were overwhelmingly dominating online personal interaction, and RF Cafe Forums activity dropped off precipitously. Regardless, there are still lots of great posts in the archive that ware worth looking at. Below are the old forum threads, including responses to the original posts. Here is the full original RF Cafe Forums on Archive.org

-- Amateur Radio

-- Anecdotes, Gripes, & Humor

-- Antennas

-- CAE, CAD, & Software

-- Circuits & Components

-- Employment & Interviews

-- Miscellany

-- Swap Shop

-- Systems

-- Test & Measurement

-- Webmaster

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

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

https://www.physics.princeton.edu/~mcdonald/examples/EM/lewin_el_17_415_69.pdf

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

_________________

At bottom, life is all about

Sucking in and blowing out.

Posted  11/12/2012