L86 ground plane requirements

IoT Modules GNSS Module
1

Hello, currently designing a pcb with L86-M33
I have the following questions:

  1. From datasheet:

The performance of embedded patch antenna depends on the actual size of the ground plane around
the module. It is recommended to design a 30 mm × 30 mm ground plane shown below. In addition,
components, especially thick ones, cannot be placed in the areas in any case (interfering vias are not
allowed either).

Should the ground plane be square?
Any differences with a circular shape?
Since the design allows it, are there benefits/downsides using a larger ground plane 40x40, 50x50, 60x60?

  1. From datasheet:

It is recommended to reserve an integrate ground layer to isolate the GNSS module from others.

My stackup on the gps area (other PCB part is Signal/GND/GND/Signal+PWR) is as follow:
GND/GND/Signal+PWR/GND and the gnd layers meet only at a ground plane corner.
Should this ground plane be kept separated from the other ground plane in the pcb (only attached to the other ground plane in a single place to provide a cleaner ground?

Should the suggested ground plane be a flooding area also under the GNSS module on all layers with the only exception being the keepout for the antenna feed point?

Is VIA stitching required for the different layers ground planes (also under the module?) What is the recommended stitching separation?

Thank you

2

Hi Thom_So,

  1. The ground plane is better to be bigger than 30 *30. But considering your PCB space, 30 *30 area may have a better use of PCB. And the ground plane can be square.

  2. It is recommended that components, especially thick ones, cannot be placed in the ground plane areas in any case.

  3. More VIA on the PCB will be better.

Best regards