Slit-Loaded Series Feed Network for Millimeter-Wave Array Antenna With a Low Sidelobe Level Over a Wide Bandwidth

A slit-loaded series feed network and its design procedure were proposed for millimeter-wave (mm-wave) array antennas with a low sidelobe level (SLL) over a wide bandwidth. In the proposed feed network, slit structures are used to suppress internal reflections within the array and to control the aperture amplitude in such a way to reduce the SLL. Four types of slit-loaded structure units are investigated to control the coupled power on an antenna element. A 1×13 end-fed and 2×26 centerfed array antennas were designed and fabricated based on the proposed design procedure, and their performances were measured. The proposed arrays were shown to have impedance bandwidths of 11.3% (75-84 GHz) and 10.2% (77.5-85.8 GHz), respectively. Moreover, they show stable radiation patterns with low SLLs under -17 dB over the frequencies of 75-83 and 78-84 GHz, respectively. The designed arrays were compared with other mm-wave array antennas and shown to have a lower SLL over wide bandwidths.