[time-nuts] GNSS Antennas (was: Rooftop antenna and splitter)

[Attila Kinali]

On Thu, 31 Jan 2019 08:51:46 -0500
Bob kb8tq <kb8tq at n1k.org> wrote:

> Looking at network analyzer sweeps, it becomes pretty apparent that whatever 
> combination of things are involved, they only work inside each of the target sub-bands.
> Once you get to the edge, it all falls apart. It comes back together once you get to
> the edge of the next sub-band. Some of that is intentional filtering so sorting it out 
> that way … not so much. 

Transmission line phase shifters are pretty narrow band.
Getting them to 5% bandwidth with reasonable phase and
amplitude stability is already not straight forward. But
for a combined GPS/Galileo/Glonass L1/L2/L5 antenna,
a bandwidth of over 30% would be needed. Not an easy task
at all. Making them work for a few select bands is a lot
easier, if still a bit non-standard. At least EM simulation
tools help a lot with that.

			Attila Kinali

-- 
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