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switch matrix - RF Cafe Forums
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pradeep
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Post subject: switch matrix
Posted: Mon Jun 06, 2005 6:36 am
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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
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maxwell |
Post subject:
Posted: Mon Jun 06, 2005 7:46 am
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Colonel |
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Joined: Mon Sep 01, 2003
6:59 pm Posts: 38 Location: Boston
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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
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Guest |
Post subject:
Posted: Tue Jun 07, 2005 12:09 am
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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
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Guest |
Post subject:
Posted: Fri Jun 10, 2005 6:43 am
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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.
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Posted 11/12/2012
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