Increasing the ground plane can increase the positional accuracy in static positioned situations according to the "u-blox M8N - ground planes, antennas and positional accuracy" post at DIYdrones measured during 10-15 minutes at a static position.
For improved comparison I looked up all dimensions of the used patch antennes and guessed ground plane sizes based on PCB dimensions, and sorted them
- by GPS IC [older to newer]
- by ground plane size [smaller to larger]:
6H 25×25×4mm patch on 38×38mm
M8N 25×25×4mm patch on 36×36mm
M8N 25×25×4mm patch on 38×38mm
M8N 35×35×3.5mm patch on 50×50mm
M8N 35×35×6.5mm patch on ⌀80mm
M8N 25×25×4mm patch on ⌀90mm
Note #1: All compared modules do contain a temperature compensated oscillator (TCXO).
U-blox GPS Antennas - Application Note
That DIYdrones post references the same U-blox antenna application note as in the answer from PeterJ. On the other hand the "Design considerations" (section 5) for "Patch antennas" (5.1) and "Ground plane" (5.1.1) of the U-blox antenna application note GPS-X-08014-A1 is not written very consistent.
measuring 25 x 25 mm2 down to 10 x 10 mm2
Remark: The patch antennas do not measure mm2 but mm1 (or shortened: mm).
Figure 17: Typical Radiation Pattern of a Patch Antenna
Remark: One should read the text above to note that this text should be: "Figure 17: Typical Radiation Pattern of a 16 x 16 mm Patch Antenna"
Figure 18: Typical gain and axial ratio of a patch antenna with
respect to ground plane size
Remark #1: "Figure 18: Typical gain and axial ratio of a patch antenna with respect to square ground plane size"
Remark #2: For which patch antenna dimensions?
- On page 19 the text becomes really sloppy:
50 mm2 square ground plane
Remark: A 50 mm2 square ground plane size measures sqrt(50) ≅ 7,07 × 7,07 mm1. What is meant here is a 50 x 50 mm1 = 2500 mm2.
- However in Figure 19 the horizontal label axis is correct:
Ground plane [mm x mm]