Wideband Phased Array Based on Vertically Trapezoidal-Ring Antenna

A design for phased arrays with wideband operation and wide-angle scanning is proposed. The radiating element of the array is a single-turn trapezoidal-ring antenna which has a compact size and a wide beamwidth in the scanning plane. The 10dB-return-loss impedance bandwidth of the single element is about 44%, and the gain variation is about 2 dB within the impedance bandwidth. A 1 × 9 linear array based on the ring antenna is designed, and a prototype is also constructed. Simulated results demonstrate that the scanning range of the proposed phased array is from −60° to 60° for each frequency in the impedance bandwidth, and the gain fluctuation is lower than 3 dB as the beam is steered in the range of ±60°; moreover, a side lobe level of lower than −10 dB is also obtained. Measured results of the stand-alone element and the resultant array are respectively shown, and they have good agreements with the simulated data.