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LaPaglia

GPS external antenna Question

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brdad and I are working on a re-radiating antenna

 

we need the formula to figure the correct cap to block the dc on the coax and pass as much of the gps signal as possible. The circuit is a choke on the power line to block the rf to the power supply and a cap from the active antenna to the re-radiatior. 47pf works as does .0068mf just looking for the best value.

 

explained better here

 

Any ideas??

 

Lapaglia icon_cool.gif

Muga Muchu (forget yourself, focus)

 

[This message was edited by Lapaglia on November 05, 2002 at 04:36 PM.]

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I got a C- in circuit analysis 10 years ago, so keeping that level of expertise in mind:

 

Wouldn't any capacitor do equally well, as long as it could handle the power and pass the needed frequency range? What are the other considerations?

 

ApK

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yes, however, the absolutely *ideal* pass capacitor would have just the right capacitance *and* inductance to be series resonant at 1.575 GHz. This perfect capacitor would have near-zero impedance at that frequency because of the resonance. It would have *lower* impedance than a larger capacitor. Hence the reason for the ideal cap

 

Lapaglia icon_cool.gif

Muga Muchu (forget yourself, focus)

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