GPS掩星探测天线相位中心的校准

Calibrating Antenna Phase Center in GPS Radio Occultation Measurements

GPS天线是GPS接收系统的关键部件,它的性能特点直接影响GPS信号的有效接收．天线相位中心的变化直接影响GPS伪距和载波相位观测量的测量．而且,相位中心并不是固定的,它会随不同的来波方向发生移动．为了更好地满足一些高精度的需要,相位中心的变化量在解算时必须被考虑进去．本文讨论了一种GPS天线相位中心的校准方法,利用微波暗室测量出不同方位角和不同俯仰角的相位方向图,即可解算出不同来波方向天线相位中心点的精确位置．对自主研制的双频GPS天线相位中心进行了测定,在仰角±75°范围内,其相位中心变化4mm以内．

Antenna is a main part in the CPS receiving system. Its performance has a direct effect on receiving CPS 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 CPS 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 CPS antenna that designed and manufactured by us was tested. The antenna phase center variation is within 4 mm at different elevations ranged from -75° to ＋75°.