Dual mode feed horn or horn antenna for two or more frequency bands

摘要

A microwave feed horn or horn antenna (11,12) for at least two frequency bands comprises a conical waveguide section (42) whose aperture at the large end has an inside diameter (D1) approximately equal to one wavelength in the lower frequency band so as to produce substantially equal power patterns in the E and H planes in the lower frequency band. The slope (ß) of the inside wall of said conical section (42) is selected to cancel the electric field at the aperture of the horn in the higher frequency band, thereby producing substantially equal power patterns in the E and H planes in the higher frequency band. A pair of straight waveguide sections (40,41) connects the opposite ends of the conical waveguide section (42).