Preferential crystal etching technique for the fabrication of millimeter and submillimeter wavelength horn antennas

Abstract

A horn antenna including first and second substrates having at least one first and at least one second horn shaped cavity formed in the first and second substrates, respectively. The horn shaped cavities taper from a narrow end and have a longitudinal axis along a plane parallel to a top surface of the first and second substrates. The second horn shaped cavity is disposed opposite the first horn shaped cavity and is a mirror image of the first horn shaped cavity. Internal surfaces of the first and second horn shaped cavities include a metalization layer. The horn antenna is fabricated by forming at least one mask having a longitudinally extending mask opening on the first and second substrates and preferentially etching the first and second substrate through the mask opening to form the first and second horn shaped cavities. A final shape of the first and second cavities is determined by the shape of the mask opening and the etching time which may be less than the time required to etch the first and second substrates to completion depending on the desired shape of the horn aperture.