Longitudinally Miniaturized H-Plane Horn Antenna With −30 dB Sidelobes Realized by Simple Blocks Redistributing the Aperture Field

A longitudinally miniaturized H-plane horn antenna with suppressed sidelobes by redistributing the field on the radiating aperture is proposed by loading a few rectangular blocks. The substantial longitudinal length reduction (around 50% of an optimal horn) will cause a nonuniform phase and nontapering magnitude distributions of the electric fields on the horn aperture, resulting in high sidelobes and decreased gain. Four pairs of rectangular blocks perturbing the fields are loaded near the radiating aperture, realizing a field redistribution for a tapered magnitude distribution and relatively uniform phase distribution on the aperture. Thus, the sidelobes are noticeably reduced to lower than −30 dB, and 10.6 dBi average gain in the frequency band of 10.5–15 GHz is achieved. A prototype of the proposed miniaturized H-plane horn antenna is manufactured and measured, and good agreements between the measured and simulated results are obtained. The proposed miniaturized H-plane horn has two advantages over other reported miniaturized horn antennas: 1) simple geometry resulting in easy fabrication and low cost and 2) −30 dB ultralow sidelobe level (SLL).