Dual Zeroth-Order Resonance Antennas With Low Mutual Coupling for MIMO Communications

In this letter, a dual-band multiple-input-multiple-output (MIMO) antenna array for mobile handheld devices is proposed. The two dual zeroth-order resonance antennas that use the composite right- and left-handed (CRLH) transmission-line theory are placed at two corners of the system printed circuit board (PCB) with an edge-to-edge distance of 12 mm (1/30 λ at 850 MHz). The neutralization-lines technique is employed to reduce the mutual coupling between the two antennas. The efficiency ( > 30%) of the antenna array can cover the GSM850/900 and DCS1800/1900/UMTS bands. The envelope correlation coefficient is lower than 0.4 in the lower band and 0.05 in the upper band. Two slots are inserted in the ground plane to further improve the isolation ( 20 dB) in the upper band. Details of the structure are described and discussed in the letter.