SparkFun Forums

[Lukel99]

I'm currently using a ceramic patch antenna similar to the one found here except with a U.FL connector, and I find that it is too directional for my application. The GeoHelix looks like a good antenna, but it is too expensive. I'd like to test the chip-scale antenna, but I had some questions about the test board in the datasheet.




1) Do I need a 50 ohm resistance in series with the antenna?
2) Should I place it as shown in this image?

3) What purpose do the holes in the ground plane serve?
4) Would it be worthwhile to create a pad that allows me to connect a component to ground in an L network configuration?
5) Should I get a surface mount U.FL connector and just get a male to male cable to connect the board I create to the gps module?
6) The module already has an LNA and SAW filter, so I assume that I don't need a redundant one on the antenna board?
7) The far end of the antenna is just soldered to a pad in the area without grounding, correct? I don't need an interconnect to go anywhere else on the board?

I admit that I know little to nothing about antenna design/ network creation and tuning, so the more specific the better. Thanks in advance!

[falingtrea]

The directionality of the GPS antenna is for a reason. Signal levels are pretty low coming from the satellite, so a high gain antenna is needed. Chip antennas like the one you are using are so low gain that they may be useless for a GPS application, without a lot of amplification.

[leon_heller]

You don't use a 50R resistor in the feed, the PCB connection is 50 ohm microstrip.

The vias are needed to ensure good grounding.

[Lukel99]

Would an omni like the chip antenna be better than a directional pointed in the wrong direction?

[Lukel99]

You don't use a 50R resistor in the feed, the PCB connection is 50 ohm microstrip.

The vias are needed to ensure good grounding.

I've been on the IRC channel, and they've been helping me a lot there. I think I'm close to having a functional 50 ohm microstrip. They also said the holes are for EMI reasons. Are you suggesting I via this ground plane to a matching plane on the other side of the PCB?

[Lukel99]

You don't use a 50R resistor in the feed, the PCB connection is 50 ohm microstrip.

The vias are needed to ensure good grounding.

I've been on the IRC channel, and they've been helping me a lot there. I think I'm close to having a functional 50 ohm microstrip. They also said the holes are for EMI reasons. Are you suggesting I via this ground plane to a matching plane on the other side of the PCB?

Seeing that this is the case. So, ground plane extends on both sides of the PCB, vias connect the 2 ground planes, microstrip runs through the center of the ground plane on the top layer?