[time-nuts] Galvanic decoupling of GPS antenna

Yuri Ostry yuri at ostry.ru
Wed Jun 16 21:09:34 UTC 2010


I'm trying to put gps (for a coarse timing sync and RTC
auto-setting) to a small controller that must be completely
galvanically decoupled from outside world. Antenna power must be
supplied from separate power source (ground potential of isolated part
of circuit can slowly float up to +/- 250 volts referenced to ground
of antenna power supply).

First thinked about using some choke to inject power, then DC-blocking
capacitor around 20-30 pf and then smt 1:1 wideband transformer, but
looks like Mini-Circuits don't make standard models for frequencies
over 1200 MHz, their search engine give me some part numbers that looks
like special order ones, and cannot be found in their catalog.

Is there any chances to get decent performance if I'll simply split
stripline (both ground and signal traces) by dc-blocking caps? Idea
looks not very good to me, of course, I suspect that i'll get all
sorts of interference right to GPS LNA input...

Maybe there is some well proven solution with easily obtainable parts?

 Yuri                          mailto:yuri at ostry.ru

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