A radio detection device includes two or more reception antennas, for
detecting a detecting object by a mono-pulse method; the radio detection
device including: a variable gain unit for discretely changing respective
signal intensity of a difference signal and a sum signal of each
reception signal received by the two or more reception antennas; an A/D
conversion unit for performing A/D conversion process on the difference
signal or the sum signal, the difference signal or the sum signal having
the signal intensity changed by the variable gain unit; an angle
calculating portion for calculating an angle by the mono-pulse method
using the difference signal and the sum signal after the A/D conversion
process by the A/D conversion unit; and a control unit for performing a
control of individually switching a conversion magnification of the
signal intensity by the variable gain unit with respect to the difference
signal and the sum signal.