Metamaterial-Based Components for a Compact Dual-Band Beam Pattern Diversity System

A compact dual-band beam pattern diversity system based on composite right/left-handed (CRLH) transmission lines (TLs) is presented. The dual-band pattern diversity system is beam-formable by employing a CRLH delay line, which introduces additional 0deg and -90deg phase delay at 2.4 GHz and 5.2 GHz respectively at the output of the dual-band rat-race coupler to two-element antenna array, which is configured to have lambda/4 element spacing at 5.2 GHz. Subsequently, this new proposed system is capable of exhibiting endfire patterns at the higher operational frequency while having sum/difference radiation modes at the lower frequency. The concept of adding CRLH components in a system leading to beam pattern diversity makes the overall system more flexible. Experimental results demonstrate two sets of orthogonal radiation patterns at dual frequencies. Good measured isolation of the system, -30.3 dB at 2.4 GHz and -20.3 dB at 5.2 GHz, validates the decoupling property.