[time-nuts] Practical Survey-In Accuracy?

Bob Camp kb8tq at n1k.org
Thu Aug 28 18:33:20 EDT 2014


Hi

Simple answer - yes. 

My observation over the years is that your typical roof absorbs quite a bit of RF starting way below GPS frequencies. My *guess* is that shingles are a bit lossy. Shingles + moisture more so. Shingles + dirt + moisture even worse. I also believe that plywood suffers the same way. Also consider that you have things like flashing, ridge vents, and gutters involved.  Somewhere below 2 MHz or so things begin to get less crazy. 

I’ve spent a lot of time putting antennas up in a lot of attics and then moving them outdoors. 

Bob



On Aug 28, 2014, at 9:30 AM, Bob Stewart <bob at evoria.net> wrote:

> Hi Attila,
> 
> 
> Is wood, nails, and asphalt shingle really that big of a problem at these frequencies?  The antenna is within 2 ft of the highest point of the roof.
> 
> Bob
> 
> 
> 
> ________________________________
> From: Attila Kinali <attila at kinali.ch>
> To: Bob Stewart <bob at evoria.net>; Discussion of precise time and frequency measurement <time-nuts at febo.com> 
> Sent: Thursday, August 28, 2014 8:15 AM
> Subject: Re: [time-nuts] Practical Survey-In Accuracy?
> 
> 
> On Sat, 23 Aug 2014 16:38:42 -0700
> 
> 
> 
> Bob Stewart <bob at evoria.net> wrote:
> 
>>   Given that my antenna is just a puck at the peak of the attic (never got around to adding the DIY choke-ring)
> 
> A choke ring will not help you much in the attic. You already have lots
> of reflecting and refracting surfaces/volumes above the antenna.
> Unless you get to the top of your roof, i wouldn't bother adding a choke ring.
> 
> 
>             Attila Kinali
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.




More information about the time-nuts mailing list