PURPOSE: To decrease a transmission loss by composing a microwave device of an integrated circuit, which includes an antenna element and amplifying circuit, and plane antenna and providing a waveguide between the feeding part of this plane antenna and integrated circuit.

CONSTITUTION: A feeding part 1 of the plane antenna is a place where all signals transmitted from the plural antenna elements are fed. Then, a dielectric substrate 2a is provided on the lower surface of the plane antenna and on the much lower surface, an earth conductor 3 is provided for a place excepting for the connection of a waveguide 5 to the lower surface of the feeding part 1. An electromagnetic wave radiated from the feeding part passes through the dielectric substrate 2 and the waveguide 5 is connected to a place where an integrated circuit 6 and the earth conductor 3 are removed. Thus, a microwave can be propagated with a small loss and non-contact.