[time-nuts] Choke Ring Antenna - Patch Placement?

[Bob Camp]

Hi

….. but the original helix antennas (at NBS) were not done quite right. They *did* have gain straight up. They re-scaled them (for a better pattern) later on. I seem to recall it being height to radius, but that probably isn't right.  

Bob

On Oct 11, 2013, at 3:45 AM, REEVES Paul <Paul.Reeves at uk.thalesgroup.com> wrote:

> Hi Bob,
> 
> Not quite true, the first couple of sentences are ok but the helix antennas used for GPS are quadrifilar volute helices, not the longer axial mode type, and their gain characteristic can be modified to provide an almost perfect pattern for satellite reception with a 'flat-top' elevation response and higher gain over the 30-60(-ish) degree area.
> 
> regards,
> 
> Paul        G8GJA
> 
> 
>> -----Original Message-----
>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On Behalf Of Bob Camp
>> Sent: 11 October 2013 01:03
>> To: Bob Stewart; Discussion of precise time and frequency measurement
>> Subject: Re: [time-nuts] Choke Ring Antenna - Patch Placement?
> 
> ..........
>> An ideal GPS antenna would not have a lot of gain straight overhead. You have less atmospheric loss in that direction. What you would >want is an antenna that has some gain at 30 to 60 degrees. That was the issue with the helix antennas. They have gain straight up >(and thus less at other angles).
> 
>> Bob
> 
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