On Fri, 16 Dec 2005 22:09:02 -0800, Roy Lewallen
wrote:

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.

Heh heh. This can also be beneficial... I was slightly involved with
this a few years ago:

"Raytheon’s Anti-jam GPS Receiver (AGR) supports the Tactical Tomahawk
missile program. The AGR is a PPS (i.e., Y-code) GPS receiver that
operates on both the L1 and L2 frequencies. When configured with a
multi-element Controlled Reception Pattern Antenna (CRPA), the AGR’s
post-correlation nulling techniques allow continued satellite track in
the presence of high levels of hostile jamming.

The AGR’s patented approach to anti-jam also implements satellite beam
steering, to further enhance the tracking thresholds, and to mitigate
the “spurious nulls” that can degrade the performance of other nulling
implementations (e.g., pre-correlation).

The AGR sequentially tracks up to eight visible satellites, and
provides high-quality pseudorange/delta pseudorange (PR/DPR)
measurements corrected for the effects of selective availability. The
Tactical Tomahawk’s navigation processor then uses the PR/DR
measurements to yield a high-performance navigation solution."

ref: http://www.raytheon.com/products/pgs/