Broadband Circularly Polarized Microstrip Antenna Array Using Sequentially Rotated Technique

In this letter, a broadband circularly polarized microstrip antenna array with a separate feed network layer is presented. A Wilkinson power divider that provides high isolation between elements and subarrays is employed in constructing the noncoplanar corporate feed network of the array. The corporate-fed 4 4 antenna array composed of sequentially rotated 2 2 subarrays is designed and fabricated. The measurement results indicate that the proposed array exhibits a 1-dB axial-ratio (AR) bandwidth of 47.8% in which the return loss is below -10 dB.