Calibrating Antenna Phase Center in GPS Radio Occultation Measurements

Antenna is a main part in the GPS receiving system.Its performance has a direct effect on receiving GPS signal efficiently.The variation of antenna phase center affects the measurement of carrier phase and C/A code.The antenna phase center is not always stable.Its coordinates will change with the variation of the signal directions.To fit some high accuracy survey,the phase center variations must be taken into account.This article presents a method for calibrating GPS antenna phase center.Phase patterns are measured at different azimuth and different elevation angles in an anechoic chamber.The coordinates of the phase center can be calculated by analyzing the data from the phase patterns.The dual-band GPS antenna that designed and manufactured by us was tested. The antenna phase center variation is within 4mm at different elevations ranged from -75°to +75°.