So, can you? Can one antenna support more than one position source?
Can you splice a GPS antenna?
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bnt83
Final Approach
There are GPS antenna splitters but few radio manufacturers support using them, and they cost about as much as an antenna.
Good to know.
weirdjim
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weirdjim
Let me set the stage for you. You are attempting to receive a signal from a satellite some 12,000 miles away transmitting a few watts which means nanovolts to your antenna (nano -- 10^-9). Now you want to split (- 3 dB) that signal still further to make your receiver work twice as hard, or take twice the time to give you position?
Boy, that seems like a hell of a good idea to me.
Jim
SkyDog58
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Canis Non Grata
Electronics and such is a foreign language to me, a lot like accounting is to others. That's why I'm glad you have the knowledge and can help me out.
So now my airplane gets to join the cool 2 GPS antenna club.
Frogs97
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bnt83
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BigBadLou
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Do not forget that an "aviation-approved" splitter costs about as much as the antenna. 
weirdjim
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Do not forget that an "aviation-approved" splitter costs about as much as the antenna.
And the guts of which are about $5.
Jim
BigBadLou
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Yup ... and the PMA sticker costs 100x that.
Timbeck2
Final Approach
Do not forget that an "aviation-approved" splitter costs about as much as the antenna.
Yep, which is why I bought my VOR/ILS splitter off e-Bay. $147 vs $25.
I seem to remember some antennas are 'active' and require power. Might not be as easy to split.
bnt83
Final Approach
There was a debate online somewhere about this very issue, equipment vendor B needs a GPS antenna and received STC that included an option to splice into a coax that feeds GPS signal from an antenna to equipment vendor A, a WAAS/LPV navigation system.
I highly doubt this would ever be acceptable on a Part 25 aircraft, but it would be handy if it was since it is very time consuming and expensive to put antennas on them with DTA of pressure vessels and all that.
cgrab
Pattern Altitude
Even though the GPS signal is weak, your GPS knows (should know) where to look for the satellites and as such can "focus" on the signal and collect enough data for the processor to get a location. The GPS remembers where it was when it was turned off so it knows where to look for the satellites. If you move a GPS a significant distance, it won't be able to find the satellites it is looking for and will take a long time to go through the whole catalog before it gives a location.