Characterization of Mesoscopic Dielectric Cuboid Antenna at Millimeter-Wave Band

A mesoscopic dielectric cuboid antenna (DCA), which can be connected to a standard waveguide, is proposed to achieve high directivity with a simple-structure and low-profile antenna compared with that of a horn antenna of same dimensions. We optimized the antenna dimensions based on simulation to maximize the antenna gain of 14.22 dBi, which is 1.9 dB higher than that of the horn antenna with the same dimensions. Simulation was performed both at 300 and 24 GHz. As a proof of concept, we designed and fabricated a scaled DCA with dimensions of 1.2λ × 1.2λ × 1.36λ and experimentally evaluated the radiation pattern at 24 GHz band. The full-width at half-maximum (FWHM) values were approximately 21% and 34% narrower than those of the horn antenna in the E-plane and H-plane, respectively. The frequency characteristic of sensitivity enhancement using the DCA as the reception antenna shows that the DCA is a nonresonant antenna with a wide bandwidth. Narrower FWHMs of the DCA have been discussed with respect to a two-dimensional nearfield phase distribution measured using the electrooptic sensing technique.