Multiple‐input‐multiple‐output antenna with pattern reconfiguration and correlation reduction for WLAN applications

Abstract

A Yagi-Uda inspired novel pattern reconfigurable multiple-input-multipleoutput (MIMO) antenna array is proposed in this article. The antenna consists of two co-axially excited microstrip patch radiators with modified ground plane. A conducting strip with an integrated PIN diode is optimally placed midway between two MIMO patch radiators placed at a distance of 0.22 0 (0 is the free space wavelength at 2.4 GHz) apart. By switching the diode OFF or ON, the conducting strip directs or reflects the main beam of the two MIMO elements at an angle of ±30 • or ±60 • , respectively, thereby, enabling 30 • wide band scanning and four switchable beams radiated by the two antennas. The novel MIMO antenna exhibits 17 dB isolation improvement between the two radiators when the diode is switched ON as a result of the beam deflection. For all switching modes, the MIMO antenna demonstrates an average gain and efficiency of 5 dB and 92%, respectively, at the resonance frequency of 2.4 GHz. The novel antenna is fabricated and measured to verify the simulation results. This simple, low-cost, efficient, and mutually isolated antenna array can be very useful in MIMO WLAN applications. K E Y W O R D S antenna, envelope correlation coefficient, mutual coupling reduction 1 INTRODUCTION Antenna engineers have been exploring multiple-input-multiple-output (MIMO) technology recently due to their inherent advantages such as increasing signal-to noise-ratio, spectrum efficiency and channel capacity, especially in a multipath environment. 1-3 Also, because of the emerging handheld nature of smart devices, patch antennas have been commonly used in MIMO antennas due to their simplicity, flexibility and low cost. However, MIMO patch antennas usually suffer from mutual coupling because of the undesired surface waves radiating inside the substrate, space waves transmitted among individual elements of the array, as well as the surface waves propagating through the ground plane. 4 This coupling This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Enhancing Performance of Millimeter Wave MIMO Antenna with a Decoupling and Common Defected Ground Approach

“…One fundamental approach involves manipulating the physical arrangement of the antenna elements. Techniques such as element spacing, orientation, and polarization are explored to reduce the coupling effect [26]. Innovative electromagnetic structures, such as metamaterials and electromagnetic band gap (EBG) structures, are employed to control the coupling between antenna elements [27].…”