GNSS Multi-Band L1/L2 Helical Antenna (SMA) BT-560

What are the offsets for the L1 and L2 phase centers of the antenna?

The figure given here says +/- 2mm https://cdn.sparkfun.com/assets/7/3/e/8 … asheet.pdf but there’s more info about the performance of the coupler here https://cdn.sparkfun.com/assets/1/b/3/f … 00P03S.pdf

The phase center offset is the distance from the antenna ARP (usually the bottom of the antenna mount) to the phase center. The specification only has phase center accuracy ±2mm. The specs show the antenna is 58.6mm high overall. The L1 and L2 phase centers will be anywhere from 0 - 58.6

Can anyone tell the actual offset values?