Substrate integrated horn antennas with improved aperture efficiency

The tapered aperture distribution of the substrate integrated horn antenna always limits its aperture efficiency and widens the antenna beam width. Therefore, the integrated H-plane horn has rarely been considered for the applications where fan-beam types of radiation pattern are required. Here, the amplitude distribution of the integrated horn aperture has been improved to be almost uniform by the three methods of applying hard boundary conditions to the lateral walls of the horn. Among these three methods, air-filled integrated horn in which the internal substrate is removed by keeping a thickness of the dielectric on the walls shows wider improvement over the bandwidth.