Most airborne GPS systems have multiple antennas and can be
made directional.
Not sure how much I can say in this forum until I check security.

The one on Zero Six Hotel is velcro'd to a plastic picture frame,
mounted upside-down over the front seat. (I generally don't carry a
passenger.) It has that little swivel "ear" antenna that points up.

I suppose it would work equally well pointing down, but I've never
tried it.

The problem I have in visualizing a jam on an aircraft is this: the
jammer is at sea level, the plane at 20,000 feet and looking to dive
to 4,000, and the satellite is at whatever, feet or miles.

So I'm on the ground on horseback with my handy Green Beret Jamming
Unit, aiming a signal at this plane that wants to attack me. Are you
saying that I can send up this umbrella beam that will wrap around the
GPS in the F-15 and thereby get between it and the satellite?

(You have probably guessed already that I majored in government.)


all the best -- Dan Ford
email: www.danford.net/letters.htm#9

see the Warbird's Forum at www.warbirdforum.com
and the Piper Cub Forum at www.pipercubforum.com