[time-nuts] Antenna for t-bolt

[Azelio Boriani]

Chuck,
I usually see GPS antennae flashed by lightning: have succedeed opening and
repairing a couple of them but at times they are too bad to do anything. I
use a network analyzer to test them after repairing here at work.

On Tue, Apr 3, 2012 at 8:24 AM, gary <lists at lazygranch.com> wrote:

> Going back to software filtering brings us full circle. ;-)
>
> Searching the interwebs, I found this:
>
>> http://www.ll.mit.edu/mission/**aviation/publications/**
>> publication-files/atc-reports/**Dinius_1995_ATC-238_WW-15318.**pdf<http://www.ll.mit.edu/mission/aviation/publications/publication-files/atc-reports/Dinius_1995_ATC-238_WW-15318.pdf>
>>
>
> They more or less state the obvious, but do provide some test results. Now
> the obvious is you want good cross polarization, i.e. the ability to reject
> the wrong polarization. Basically the intended signal is RHP, but the
> direct bounce is LHP, so you want the antenna to have good RHP gain and
> poor LHP gain, or more accurately, the ratio between the two.
>
> The next source of interference is the bounce from the ground, which could
> be multiple hops and thus potentially RHP. That is where a ground plane or
> choke ring came in handy.
>
> Page 37 has the conclusions.
>
> I have a similar Trimble patch somewhere (Trimble 16248-50). It has never
> seen action (at least by me) since the voltage requirement is quite odd. I
> don't have it in front of me, but I think 4.5v. That particular antenna
> also has a SAW filter in it. It is a Navy item.
>
>
>
> On 4/2/2012 10:15 PM, Hal Murray wrote:
>
>>
>> caf at omen.com said:
>>
>>> Presumably a timing antenna would block low elevation signals to reduce
>>> multipath.
>>>
>>
>> Maybe, but there is a software aspect to the filter.  You get to select
>> the
>> elevation angle.
>>
>> I don't remember seeing any specs about the filtering angles of various
>> antennas.  Has anybody seen something like that?
>>
>>
>>
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