Wideband Microstrip Comb-Line Linear Array Antenna Using Stubbed-Element Technique for High Sidelobe Suppression

This paper presents a novel wideband microstrip comb-line linear array antenna using end feeding developed in the millimeter-wave. The proposed antenna is designed for 28 GHz and has 12 elements. The reflection-canceling slit structure technique is adopted to develop a broadside beam with low reflections at the input. The proposed array is designed using stub-studded radiating elements that create more resonances to broaden the impedance bandwidth. The structure is a novel comb-line linear array antenna with stub-studded radiating elements and was developed by applying stubs to eight of the radiating elements of the array to increase the input impedance bandwidth. This helps to attain a wideband linear array antenna on a single dielectric substrate, which conventionally has a narrow bandwidth. The input impedance bandwidth is from 23.5 to 33.11 GHz, which is equivalent to a bandwidth of 33.95%. The radiation pattern bandwidth is from 27.5 to 29.25 GHz for sidelobe levels of below -20 dB equivalent to a bandwidth of 6.167%. The proposed antenna array presents features such as a simple structure with low fabrication cost and an enhanced impedance bandwidth with high sidelobe suppression. The feasibility of the proposed antenna array was evaluated by simulation and measurement in the millimeter-wave band.