Design of a Compact HMSIW Cavity-Backed Dual-Band 4-Port MIMO Antenna

Abstract

In this article, a novel, compact, dual-band 4-elements multi-input and multi-output (MIMO) antenna diplexer is investigated, prototyped, and tested. The proposed design is based on a planar half-mode Substrate Integrated Waveguide (HMSIW) technology, that diminishes size by 50% than of full-mode Substrate Integrated waveguide (FMSIW) cavity. Later, to enhance the bandwidth around 50%, a rectangular slot is introduced at the center of each cavity. The slot splits the dominant mode half-TE110 into an odd- and even-modes. The proposed antenna resonates at 3.3 GHz and 3.4 GHz when either Port-1 or Port-3 is fed, and Port-2 or Port-4 are terminated with matched loads. Similarly, the antenna operates at 4.2 GHz and 4.3 GHz, either Port-2 or Port-4 is fed, and the rest are matched terminated. The intrinsic isolation between any two ports is achieved below -23 dB with an antenna footprint of 1.0λ <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</inf> × 0.8 λ <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</inf> . The average gain in the lower and upper frequency bands are around 5.15 dBi and 6.1dBi, respectively while radiation efficiency is more than 80% in both frequency bands. The envelope correlation coefficient (ECC) of the MIMO antenna has been achieved < 0.13, directive gain (DG) around 9.9 dBi, and mean effective gain (MEG) around -3.05 dB in both frequency bands.