[time-nuts] GPS antenna??

Bob Camp lists at rtty.us
Mon Apr 8 17:59:50 EDT 2013


Hi

If the windows are of the permanently fixed variety - how about a rock …:)

Since most windows are likely pretty good sized, and this *is* a microwave conference …. how about some sort of meter square purpose built antenna? 

For the uber-exotic approach - modulate a laser with the GPS signal and move the signal through the window as light. 

Bob



On Apr 8, 2013, at 5:32 PM, Robert Atkinson <robert8rpi at yahoo.co.uk> wrote:

> Hi Alan and Tom,
> Note that under the Wireless Telegraphy Act 2006  here in the UK, active GNSS repeaters have to be licenced. See 
> http://194.33.160.59/radiocomms/ifi/enforcement/gpsrepeaters/
> and 
> http://stakeholders.ofcom.org.uk/enforcement/spectrum-enforcement/gpsrepeaters/
> Even a "normal" active antenna connected to another antenna would qualify as a repeater. Also the "transmit" antenna must be indoors so your through window scheme is out. How about a strip of closed cell foam with a slit for the coax  that you can trap in the window? This will allow the coax in while keeping the drafts out.
> 
> Regards,
> Robert G8RPI.
> 
> 
> 
> 
> ________________________________
> From: Tom Van Baak <tvb at LeapSecond.com>
> To: Discussion of precise time and frequency measurement <time-nuts at febo.com> 
> Sent: Monday, 8 April 2013, 22:12
> Subject: Re: [time-nuts] GPS antenna??
> 
> Alan,
> 
> Google for words like GPS re-radiator or GPS repeater. There are also units on eBay. If not to buy, at least to study examples.
> 
> The one I have is made by www.gpssource.com but it seems you could build one yourself. It's easy to test by looking at your indoor SV count and reception levels. With patch antennae you don't have to worry about RHCP issues, right?
> 
> /tvb
> 
> ----- Original Message ----- 
> From: "Alan Melia" <alan.melia at btinternet.com>
> To: "time-nuts measurement" <time-nuts at febo.com>
> Sent: Monday, April 08, 2013 9:59 AM
> Subject: [time-nuts] GPS antenna??
> 
> 
>> Hi all an interesting problem you may have encountered, I want to use a GPS 
>> frequency standard inside a building with no opening windows (opening 
>> windows are known as air conditioning in the UK :-))  )
>> This is part of a two day amateur microwave conference so we should have the 
>> expertise.
>> 
>> I intend to try and pass the signal through a a double glazed glass window 
>> unit (hopefully not metalised) using a couple of patch antennas. The outer 
>> GPS antenna is active so will need  a 5v supply via an inserter. Inner patch 
>> active, outer patch passive to avoid problems of feedback. Main antenna can 
>> be shielded from the "coupling" either physically or with a slab of 
>> absorber.
>> 
>> Has anyone tried this?.... does it work?.....any gotchas?
>> 
>> Thanks
>> Alan
>> G3NYK 
> 
> 
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