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Old December 17th 05, 06:09 AM posted to rec.radio.amateur.antenna
Roy Lewallen
 
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Default Passive reradiating antenna

Toni wrote:
Hi,

I've seen here before suggestions about using a tuned loop to increase
the gain of radio controlled clocks. Do you think this could also be
used to increase the gain of a gps receiver?


No. If you were to increase the gain of your GPS antenna, either by
redesign of the antenna or by an external parasitic structure of some
sort, it would have to result in a narrower pattern. So you'd reduce the
reception in some directions.

I guess that loop should be 1wl circumference, or about 2 1/2 inch
diameter, easy enought to cary in a pocket and play with.

I know one can not have more than 0 dB with full omni, I just guess the
minimalistic antenna in pocketable gps is way below 0 dB and could
maybe be improved a little.


0 dB relative to what?

Once you get the desired coverage angle, the only way to improve the
reception of the GPS is to improve the receiver signal/noise ratio. The
only way you can do that from outside the GPS is to use an external
antenna with a preamp having a lower noise figure than the GPS's receiver.

Could this be modeled in EZNEC, one segment with some series resitance
for high loss antenna and the other 19 to simulate the loop?


I'm not sure what the "high loss antenna" is. If you mean the GPS
antenna, it's not high loss at all, but is likely very efficient. If
it's a patch antenna, you can't model it at all with EZNEC. But even if
it's a quadrifilar helix, you can't model it with one segment.

Roy Lewallen, W7EL