[TowerTalk] antenna for data collection out at sea

[mpride@us.ibm.com]

With respect to a dual system (148 MHz and GPS - 1500 MHz) the system
requires a receiver for the GPS only, there is no transmitter involved at
1500 or 1200 MHz.  There are commercially  available dual band antennas for
this type of purpose.  The GPS antenna of course has to be circularly
polarized and zenith facing (pointed up into the sky) where the 148 MHz
antenna is vertically polarized. The commerically available ones have this
basic design.

You may be already aware that a simple patch antenna that measures about 1
inch square makes a fine GPS antenna coupled with a 20 to 30 dB gain preamp
and could be made moisture resistant.  Check with Marine stores for these
kinds of antennas, but to keep things low cost, consider having 2 separate
antennas mounted on a convenient package.

I don't think the GPS signals will be received at 1800 M below the surface
(if that what you are planning).  Maybe 1 meter below the surface, but not
1800 M.

Regards,

Mark, K1RX



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