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GPS antenna

Hello This is actually not about antenna, but about signal propagation. I need to add GPS capability to existing product. The only available place is under rubber keypad (the rest of the instrument is EMI coated anyway). The keypad is grey... The active antenna/GPS module combo I picked up works fine until I insert them inside of the box (under the keypad). Antenna is 10x10mm, keypad is ~ credit card size. There is no coating there. Antenna picks

6-8 satellites when it sees sky (ceiling, actually but there is no metal between it and the sky), and loses all of them once I try to slide it in the instrument. I know nothing about plastics. What is the chance that they added some conductive/magnetic filler to make (keypad) rubber grey (or soft or whatever other properties it has)? Any clues? Thanks!
Reply to
Michael
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Notebook type (and most other) keypads have a conductive array "below" each press point - which is used to scan the keys. It is this conductive array that acts like a shield; add a gain of

40dB more or less...
Reply to
Robert Baer

Our keypad is made of few small discreet membrane switches, the rubbery part has ~1/8" long feet pushing them, the antenna is supposed to fit between them.

Reply to
Michael

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I can recommend a good (great) antenna design engineer if you need one (USA). Clearly, this thing looks like it's going to have a lot of tuning and coupling issues.....

Reply to
mpm

It may be that your instrument has very weak spurious radiation at

1575MHz that is causing a problem.

As an aside...did you know that your remote keyless car thingy is typically at 315MHz and that the 5th harmonic of that falls right on the GPS band?

Reply to
brent

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