An SIW Horn Antenna With Flat-Top Beam for Millimeter-Wave Applications

In this letter, a flat-top beam (FTB) antenna realized by a substrate-integrated waveguide (SIW) H-plane horn is presented for millimeter-wave applications. Its FTB is formed by manipulating electromagnetic fields on its radiating aperture. In addition, a multibeam antenna array consisting of six FTB antenna elements is also investigated to provide a horizontal omnidirectional coverage. For validation, both the elementary FTB antenna and multibeam antenna array are simulated, fabricated, and tested. It can be observed that the measured and simulated results are in good agreement. For the elementary antenna, a good FTB pattern can be maintained across the whole operating band, which is wider than any previous FTB work. Moreover, a measured peak gain of 7.5 dBi is obtained, with a side-lobe level lower than -17.2 dB. For the multibeam antenna array, a nearly uniform power distribution is obtained in the horizontal plane by merging six FTBs. Overall, the proposed antenna has the advantages of simple structure, single feeding, ease of integration, and good radiation performance, demonstrating its potential for millimeter-wave applications.