Compact bandwidth-optimized two element MIMO antenna system for 2.5 – 2.7 GHz band

This paper presents design of a compact two element planar MIMO antenna system for a USB dongle operating in the 2.5-2.7 GHz frequency band. The proposed MIMO antenna system consists of two meander line monopoles and uses a decoupling technique based on a direct connection of the antenna elements to improve the antenna system diversity. In order to provide the required MIMO antenna system bandwidth, the optimization of the connection line parameters was performed. The designed MIMO antenna has the compact size of 10 mm×20 mm (that is 6 and 12 times lower in corresponding dimension than the operating wave length), more than 200 MHz bandwidth for the return loss S
₁₁
and the insertion loss S
₂₁
simultaneously, and exhibits pattern diversity when different antenna elements are excited. Also the designed antenna has planar structure (standard FR4 PCB technology) and, therefore, low production cost. The performed analysis of the envelope correlation coefficient shows excellent MIMO antenna system characteristics. Experimental measurements of the fabricated antenna system prove the simulation results.