For HAS/E6: Choke-Ring & “UFO” Antennas are performing much better than Helical & Patch/Puck Antennas. I guess that’s not unexpected. My Helicals and Pucks “can” produce accurate HAS/E6 positions, but they can also get it wrong fairly easily.
Antenna selection appears to be much more critical for Galileo HAS/E6 than for General RTK due to the underlying processing techniques. The error-canceling benefits of Double-Differencing in RTK enable smaller antennas to maintain a stable integer fix. However, the Zero-Difference nature of HAS/E6 leaves the solution vulnerable to uncompensated local errors, requiring superior antenna hardware to ensure an accurate PPP convergence.
Over-Simplified Summary: HAS/E6 Convergence guesses wrong less often with a good antenna verses with a small one.
I know that’s an obvious statement, but my testing shows a substantial difference in HAS verses RTK’s ability to perform with inferior antennas.