[time-nuts] frying pan antenna

Bruce Griffiths bruce.griffiths at xtra.co.nz
Tue Mar 16 03:28:42 UTC 2010


Below 600C the only significant source of microwave absorption in wood 
is the water content:
http://pubs.acs.org/doi/abs/10.1021/ie901336k

Bitumen has very low microwave loss so if the asphalt doesnt have any 
taconite in it its loss should be low.
http://www.nrri.umn.edu/egg/REPORTS/TR200419/CTS0510.pdf

You could always try the microwave oven test with some samples.

One thing to consider is the reflection loss from the roof due to its 
non unity dielectric constant.


Bruce

Mike Naruta AA8K wrote:
>
> True Bruce.  Alas, those trees to the West are matched by
> trees to the East.  Power lines run in front of the house
> to the South.  And the towers, guy wires, and wire antennae
> are to the North in the back yard.  It's like looking up
> a funnel to see the satellites.
>
> I have another Motorola patch under the roof that also works.
> What is the dielectric of wood sheathing and asphalt shingles?
> I may try the cake pans on the inside one; not much snow
> inside the attic.  :)
>
>
> Mike - AA8K
>
>
> Bruce Griffiths wrote:
>> A pity that the GPS receiver elevation mask can't generally be made 
>> to be azimuth dependent.
>> You could then have a higher elevation limit in the direction of 
>> those trees.
>>
>> However, it is possible in principle with an M12+T, M12M T or similar 
>> timing receiver which provides the relative timing contribution of 
>> each SV to the solution, to back out the contribution of a given SV 
>> and compute the corresponding timing correction for software 
>> correction of the PPS pulse timing.
>>
>> Bruce
>>
>
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