Broadband Circularly Polarized Bowtie Antenna Array Using Sequentially Rotated Technique

A circularly polarized bowtie antenna array for wideband application is presented, which employs a dual-polarized bowtie antenna with electromagnetic coupling feed as the radiating element. By introducing a swallow-tailed feed-strip and an end vertical loading, a wide impedance bandwidth is achieved with a reduced antenna size, without using any impedance matching circuits. Four array elements are used in a 2 × 2 configuration to obtain high gain performance. To improve the axial ratio (AR), the array elements have been sequentially rotated. The proposed antenna has an impedance bandwidth for VSWR ≤ 1.5 of 46% ranging from 1.1 to 1.77 GHz. The AR results are better than 0.75 dB within the impedance bandwidth. The gain of the array varies from 10.8 to 12.2 dBi within the operating band. Acceptable agreement is found between the simulated and measured results, verifying the proposed design with wide impedance, AR, and gain bandwidths.