Two-dimensional dual-polarized millimeter-wave horn antenna arrays

A two-dimensional dual-polarized monolithic horn antenna array has been designed for millimeter-wave applications. The antenna consists of two dipoles suspended at different positions from the apex inside an etched pyramidal cavity. For dual-polarization, the dipoles are oriented perpendicular to each other. The dipoles are integrated on a 1.2- mu m thick silicon-nitride membrane. The theoretical pattern is calculated by approximating the horn structure by a cascade of rectangular waveguide sections. The boundary conditions are matched at each of the waveguide sections and at the aperture of the horn. Due to the symmetrical design of this antenna, there is no coupling between the dipoles and the patterns are calculated for each polarization independently. The mutual coupling between the dipoles was measured using a microwave scale model and found to be less than -30 dB. The input impedance and resonant length were also measured, and values in the range of 50-150 Omega for the resonant resistance and 0.19-0.24 lambda for the resonant length were found.<>