Design of a high gain and low sidelobe coaxial collinear antenna array

A high-gain and low-sidelobe coaxial collinear (COCO) array antenna is developed in the UHF band. The bandwidth of the array element reaches to 5.8% and the gain is 6.054dB. To suppress the grating lobes, a new method of spacing array element is considered and confirmed. A 42×15 coaxial collinear array antenna is designed with this method. The grating lobes of the array is down to -30dB. The gain of finally array is 38dB, sidelobe level is less than -30dB, the Half-Power Beam Width (HPBW) is 2.16 degrees in E-plane, and 2.12 degrees H plane.