switch matrix - RF Cafe Forums

The original RF Cafe Forums were shut down in late 2012 due to maintenance issues - primarily having to spend time purging garbage posts from the board. At some point I might start the RF Cafe Forums again if the phpBB software gets better at filtering spam.

Below are the old forum threads, including responses to the original posts.

-- Amateur Radio
-- Anecdotes, Gripes & Humor
-- Antennas
-- CAE, CAD, & Software
-- Circuits & Components
-- Employment & Interviews

-- Miscellany
-- Swap Shop
-- Systems
-- Test & Measurement
-- Webmaster

pradeep

Post subject: switch matrix

Posted: Mon Jun 06, 2005 6:36 am

Lieutenant

Joined: Mon Jun 06, 2005 12:38 am
Posts: 2

hi
i am working on switch matrix in the frequency range of 18GHz.
when i interconnect the switches(electromechanical switch) in series by using semi rigid cable, return loss is becoming bad in ku band frequencies.
please give ur suggestion for improving the performance.
regards
pradeep

_________________
pradeep
Research engineer
INDIA

maxwell

Post subject:

Posted: Mon Jun 06, 2005 7:46 am

Colonel

Joined: Mon Sep 01, 2003 6:59 pm
Posts: 38
Location: Boston

Can you replace most or all of your coaxial cable with waveguide? Waveguide loves 18 GHz and you eliminate the lousy connectors that coax has to use. In fact, a lot of your cable problems could be due to the connector interfaces. One way to check is to do a TDR on the path and see if your reflections are concentrated at connectors. Sometimes a judicious trimming of cable lengths can significantly reduce VSWR induced ripple and slope.

- Maxwell

Guest

Post subject:

Posted: Tue Jun 07, 2005 12:09 am

hi max,
thank you for your reply.I may not be able to use wave guide in system.i have to use coax only. please post your suggestion regarding connectors and cables works at 18GHz

regards
pradeep

Guest

Post subject:

Posted: Fri Jun 10, 2005 6:43 am

You need to minimize the cable length to under a quarter wave length in order to minimize the standing wave, you may want to scrap the cable and use sma "bullets" to connect the switches. Another trick is to adjust the phase in between the switches by either changing the length of the cable or using a phase shifter. I had a similar situation once where I was not meeting my output power requirement due to mismatch in between various modules. Like you, I was using cable. I resolved the issue by pains takingly adjusting the cable length in between each module until I obtained optimized perfromance.

Posted 11/12/2012

Webmaster:

Kirt Blattenberger,

BSEE - KB3UON

RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The World Wide Web (Internet) was largely an unknown entity at the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps while tying up your telephone line, and a nice lady's voice announced "You've Got Mail" when a new message arrived...

All trademarks, copyrights, patents, and other rights of ownership to images and text used on the RF Cafe website are hereby acknowledged.

My Hobby Website: AirplanesAndRockets.com

My Daughter's Website: EquineKingdom