Test signal generator for coherent air-to-ground radars

Claim 1

Apparatus for ground testing of air-to-ground microwave doppler radar systems, comprising: a stationary target; a stationary radar transmitter remote from said target for propagating microwave signals toward said target; antenna means remote from said target and said transmitter for receiving the microwave signals reflected from said target, said antenna means including a rotatable vertical shaft, a motor drivingly connected to said shaft for rotation thereof, first and second arms extending in opposite diections from the top of said shaft, a microwave antenna positioned at the free end of said first arm, a counterbalancing weight at the free end of said second arm, waveguide means extending from said antenna through said first arm and said shaft to the base of said shaft; sensor means operatively connected to said waveguide means at the base of said shaft for providing signals indicative of the angular position of said antenna; and electronic means receiving the microwave signals from said waveguide means and angular position signals from said sensor means, for providing a display signal of the realistic amplitude and doppler history of the target-reflected microwave signals.