Garmin GpsMap 396 - Flight Test

GPS units need to have a "quadrifilar" design antenna or they will not
work well.
I had an older Garmin that I connected to an older stock GPS antenna
outside the Cherokee and it still would not work reliably. There is
information on this design antenna on the web. Magellan uses the quad.
http://www.qsl.net/n8imo/qha_4.html

You are either funning us, or you have absolutely no idea what a quadrifilar
antenna is. A two foot high antenna mounted on a 6 foot high mast isn't
going to mount easily on anybody's airplane, let alone a homebuilt.

Your "older Garmin ... connected to an older stock GPS antenna" probably
didn't have an amplifier in the antenna with enough gain to overcome the
loss in the coax you used.

Most GPS external antennas use a modified patch antenna with a 25-30 dB
amplifier mounted to the backside of the patch.

Jim


"darthpup" wrote in message
oups.com...
GPS units need to have a "quadrifilar" design antenna or they will not
work well.
I had an older Garmin that I connected to an older stock GPS antenna
outside the Cherokee and it still would not work reliably. There is
information on this design antenna on the web. Magellan uses the quad.
http://www.qsl.net/n8imo/qha_4.html

In article ,
"RST Engineering" wrote:

You are either funning us, or you have absolutely no idea what a quadrifilar
antenna is. A two foot high antenna mounted on a 6 foot high mast isn't
going to mount easily on anybody's airplane, let alone a homebuilt.

Jim, have you ever seen the GPS antenna for the Goodyear Blimps?
Of course not! Do you think they want everyone to know they have a two
foot high quadrifiler antenna mounted on a six foot mast buried in the
middle of the envelope?