[time-nuts] Effect of temperature on cheap puck style GNSS antennas?

[Matthias Welwarsky]

Dear list members,

My DIY GPSDO has a rather well defined dependence to the environmental 
temperature, which correlates almost linearly with a frequency shift of the 
OCXO. However, at times I see the error against the GNSS reference increasing 
with its case temperature not warranting such effect.

My antenna is one of those cheap, magnetic, active antennas you'd put on a car 
roof. It's facing south and has full exposure to the sun, obviously.

During sunrise I see the TIC error increasing 20ns-30ns over lets say 2000 
seconds. The GPSDO case temperature rises, too, during that time as the room 
temperature increases, but it is only by 0.3°C.

I'm wondering if the temperature of the antenna, which of course rises much 
faster than the room temperature, can have an effect of this magnitude?

Best regards,
Matthias