BoatBanter.com - View Single Post

Tom Francis - SWSports

On Mon, 05 Jan 2009 13:49:18 -0500, wrote:

I am sure the antenna itself is the key

It is and it depends on whether it's a passive or active antenna. You
can also modify passive antennas to make then semi-active and actives
to make them semi-passive.

It's a whole science unto itself.

Most internal GPS antennas (and external antennas also) are bifilar
meaning that the antenna acts as a simple 1/2 wave dipole antenna but
it has reduced axial length - constructed as a helix antenna in which
the turn angle can be used to control the ratio of the orthogonal
linear field components and the input impedance. The advantage being
that you can build a flat, round, square, oblong, egg shaped or what
ever type antenna which will receive signals along the edges of the
antenna in addition to signals at acute 90 degree angles.

Aren't you glad you asked? :)

--

"Every normal man must be tempted at times
to spit on his hands, hoist the black flag,
and begin to slit throats."

H. L. Mencken