A high frequency amplifier is mounted in the immediate vicinity of a feeder of a microstrip antenna. A microstrip antenna includes a dielectric member and a grounded conductor member which is applied thereto. A second dielectric member is disposed on the side of the grounded conductor member which faces away from the dielectric member, and the high frequency amplifier is mounted on the surface of the second dielectric member which faces away from the grounded conductor member, and is connected to the feeder of the microstrip antenna. A transmission distance between the feeder and the high frequency amplifier, which represents an initial amplifier stage, is greatly reduced, thus drastically reducing disturbances caused by external noises and improving the noise figure of a receiving equipment.