A Flat-Top Beam Nonuniform Waveguide Slot Antenna Based on Beamforming

This letter presents a nonuniform waveguide slot antenna with a flat-top beam. The radiation from the slot can be regarded as magnetic current radiation. By introducing the mode compression concept, the far-field distribution of the antenna is derived. The desired magnetic current distribution, and hence beamforming, can be achieved by adjusting the relative positions of the slots and their distance from the waveguide centerline. To verify the proposed method, a nonuniform waveguide slot antenna is designed, fabricated, and measured. The measured results are in good agreement with the simulations. The H-plane pattern of the proposed antenna achieves a flat-top beam within the angular range of −40° to 40°, with a variation of less than 2 dB and a beam slope of 0.81 dB/°.