A Wideband Pattern-Reconfigurable Loop Antenna Designed by Using Characteristic Mode Analysis

In this letter, a pattern-reconfigurable antenna for indoor communication is proposed, which can provide stable conical and broadside beams. Although this type of pattern-reconfigurable antenna can provide large radiation coverage, it usually suffers complex structure, narrow bandwidth, and distorted pattern. In order to get rid of the complex radiators, a simple loop patch is introduced to generate the conical and broadside beams. Through slotting the loop patch with the aid of characteristic mode analysis, the two desired radiation modes can be well excited in the same band. Meanwhile, the modified loop patch can provide stable radiation patterns by suppressing unwanted higher order modes. For achieving the reconfigurable beams, a reconfigurable feeding network is designed to switch two working modes. Finally, the proposed pattern-reconfigurable antenna is fabricated, and the measured overlapped 10 dB operating bandwidth is about 27.3% ranging from 3.61 to 4.75 GHz. The results show that the proposed pattern-reconfigurable antenna has a wide bandwidth and stable radiation patterns, which exhibits attractive potentials for fifth-generation (5G) indoor communication in sub-6 GHz.