To compensate for a phase error caused by the difference between paths for a sum signal and a difference signal from a feeding section to a tracking receiver and a temperature change between the paths even when a connection length between the feeding section and the tracking receiver gets longer due to mount restriction such as assurance of visual field for an antenna or the like.

This sensor uses an IF signal oscillator 30 that generates a signal with a frequency equal to that of an IF signal, generates a reference RF signal from this reference IF signal and an LO signal, uses a calibration sum signal coupler 39 and a calibration difference signal coupler 40 to give this reference RF signal to a sum signal output terminal and a difference signal output terminal of a feeding section 3 and has a memory 51 that controls a phase shift amount of a phase shifter controller 50 on the basis of an output of an elevation angle error signal monitor 49 and a temperature monitor signal 52.