LAUSR

A substrate integrated waveguide (SIW) H-plane horn antenna with miniaturized longitudinal dimension and increased gain is proposed by loading slow-wave (SW) structures in the form of metallized blind via-holes inside the flare region of the horn for vehicular millimeter wave communications. The slow-wave structure can reduce the phase velocity around the center line of the broad wall and compensate the large phase difference between the center and edge of the aperture caused by reduction of longitudinal length of the horn. Compared with optimum horn with the same aperture width, the gain of miniaturized SIW horn is successfully increased, while the longitudinal dimension is decreased. A SW-SIW horn antenna which covers the 28 GHz band (27.5–28.35 GHz) allocated by Federal Communications Commission for the 5G millimeter wave communications is designed to verify the feasibility of the miniaturized SIW horn antenna facilitated by the proposed slow-wave structure. The SW-SIW horn realizes 53.83% reduction of longitudinal length compared with the optimum horn. The gain of the SW-SIW horn is improved by 1.1 dB on average over 27.5–28.5 GHz compared with optimum horn. A prototype of the proposed SW-SIW H-plane horn antenna is manufactured and measured. The measured results agree well with the simulations.