A Broadband Circularly Polarized Planar Antenna Array Using Magneto-Electric Dipole Element With Bent Strips for Ka-Band Applications

Abstract

This letter proposes a Ka-band broadband circularly polarized (CP) planar array based on the magneto-electric (ME) dipole structure. The antenna element consists of linearly polarized (LP) ME-dipole and two rotationally symmetrical bent strips. The two strips are connected to the opposite side of the LP ME-dipole to obtain a rotating electric field required by CP radiation. A feed structure of microstrip is implemented to excite the antenna element through an H-shaped coupling slot. The tightly coupled array technique is adopted to enhance the axial ratios (ARs) of the element. The proposed CP element realizes an AR bandwidth of 28%. Then, an 8 × 8 array with a 1-to-64 full-corporate feeding network is designed for experimental validation. The test results indicate that the 8 × 8 array prototype exhibits an impedance bandwidth of 50% covering 24 to 40 GHz, a 3 dB AR bandwidth of 28% covering 26.7–35.3 GHz, a gain between 20.6 and 22.1 dBic over the whole overlapped bandwidth, and a radiation efficiency higher than 75%. Attributed to the excellent CP performance and ease of integration with front-end circuits, the designed array is a good select for Ka-band wireless and satellite communications.