The MU radar with an active phased array system: 1. Antenna and power amplifiers

Abstract

The MU (middle and upper atmosphere) radar of Japan is a 46.5‐MHz pulse‐modulated monostatic Doppler radar with an active phased array system. The nominal beam width is 3.6° and the peak radiation power is 1 MW with maximum average power of 50 kW. The system is composed of 475 crossed three‐subelement yagi antennas and an equivalent number of solid state power amplifiers (transmitter‐receiver modules). Each yagi antenna is driven by a transmitter‐receiver module with peak output power of 2.4 kW. This system configuration enables very fast and almost continuous beam steering that has not been realized by other mesosphere‐stratosphere‐troposphere radars. Also, a variety of sophisticated operations are made feasible by dividing the antenna array into several independent subarrays. A brief description of the system, particularly its antenna and power amplifiers, is presented herein.