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Active ans passive GPS antennas

 
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Anubis
Antenna-Theory.com Newbie


Joined: 08 Oct 2015
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PostPosted: Thu Oct 08, 2015 1:11 pm    Post subject: Active ans passive GPS antennas Reply with quote

Hi all,

I have a question concerning active and passive GPS antennas. A passive GPS antenna contains only a patch antenna whereas an active one also adds an integrated LNA + filters.

Generally, for active antennas, the DC supply needed for the LNA comes directly from the SMA cable. My question is : if there is no DC supply whatsoever intended for the active antenna, does it behave as a passive antenna or not ? I mean, will the active antenna still work without any DC supply ?

Thanks for any answers.

Anubis
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admin
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Joined: 03 Jan 2007
Posts: 197

PostPosted: Thu Oct 08, 2015 5:48 pm    Post subject: Reply with quote

It *might*. It depends on the insertion loss of the LNA in the GPS band when the LNA is not powered. It may be noticeably worse (or they may install a switch that connects the LNA only when power exists).
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helix
Antenna Theory Regular


Joined: 29 Jan 2015
Posts: 64

PostPosted: Wed Oct 14, 2015 2:46 pm    Post subject: Reply with quote

I'd guess that most active GPS antennas are terrible when they're unpowered.
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