[Wswss] Re: [Mw] Re: Simple 432 MHz return loss bridge

[Doug McGarrett]

Any small device is probably a 3dB hybrid.  I doubt if you want
to lose half your power, or half your incoming signal.  
What's the problem with a directional coupler?  That's
the way the entire microwave world works.  Build or
buy a 20dB coupler, and your prayers are answered.  I can design 
for you a 20dB coupler in stripline, if you want to build your own.
Free.  Just tell me what kind of material you can use and etch.  This is 
not a "complex" thing--it's pretty simple.  Two pieces of microwave
material screwed together with lots of screws, and some connectors.
A decent 50 ohm load.  Done.

--wa2say

At 01:48 AM 1/6/2005 +0000, Cliff Buttschardt wrote:
>Hi all.  Seems some simple problems can get awfully complex.  I would like to
>build a small signal----that is signal generator operated----return loss
bridge
>for the 420 to 450 band.  Most of the publications show complex microstrip
>designs.  I visualize two panel mount type "N" connectors spaced by the width
>of a BNC panel mount connector, that is about one inch, all soldered
together.
>Then possibly a #16 wire between the type "N's" and a ferrite bead suspended
>between the two, with pickup loop of teflon coated wire of say #28 size.  The
>loop is terminated on one side with a fifty ohm resistor.  I've used ferrite 
>#77 material which should be good to 440 MHz, but maybe this is wrong.  
>     The best directivity I can get is only 8 db or so using a spectrum
analyzer
>as a detector.  Is this the problem?  From the RSGB handbook is appears a
high
>impedance detector should be used but so far that has not improved things.
>There has to be a way of putting a small device such as this between a signal
>generator and an antenna rather than a complex directional coupler.  
>     If I am trying too hard that is just as valuable an answer as any BUT
>HP has a small device such as this and we should be able to duplicate it!!
>Cliff K7RR
>_______________________________________________
>Microwave mailing list
>microwave at wa1mba.org
>http://www.valinet.com/mailman/listinfo/microwave
>