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Suitable GNSS (GPS L1) antenna for a smart watch application
Can you please advise which, if any, of your passive GNSS antennas might be suitable for use an as internal (GPS L1) antenna in a smart watch application? Keeping in mind that space is extremely tight, the main PCB is circular (~37mm diam), there is some off-pcb room, there's an LCD screen above and a human body (and battery) underneath it.

I've determined the following from your datasheets:

SR4G008 Sinica - lists wearables, min 40x20 PCB with device on long edge. Performance looks quite degraded at 40mm, so I'm assuming a smaller, circular PCB will be even worse.

SR4G013 Belti - lists wearables, designed for small ground planes, states "High  resistance to detuning makes this antenna ideal for small wearable devices.", although PaulAustralia suggests here ( that it is very sensitive to surroundings. No ground clearance required.

SR4G053 Raptor - lists wearables, multi-band (not required, but may be at some point). Requires no ground on 3 sides, what about the 4th side? What is the sensitivity to ground or lack of it here? The eval board is 85mm high, so I'm guessing it needs quite a lot.

The M20047-1 active model lists smart watches in the applications section, but page 12 of the datasheet states that "edge of the host PCB that the module is to be placed at must be a minimum of 40mm in length.", which is not really feasible for a smartwatch application.

We're also investigating possibly placing the antenna along with a SAW+LNA in the band. Would any of the above be workable in this position?


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1 Answer

answered by

Hello RogW,

The Sinica would be your best option. You should definitely consider adding a SAW and LNA to boost the receive GPS signal. Your watch will need it since the ground plane is smaller than 40mm. We have also worked with other smart watch designs with some success in adding a small monopole to the bezel of a watch. Please contact to further our discussion.

Best regards,

Geoff S.

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