Frequency/Isolation Reconfigurable Compact Novel Quad-Element MIMO Configuration for WLAN/WiMAX Applications

Abstract

A compact novel quad-element MIMO antenna with frequency and isolation reconfigurable feature is introduced for WLAN and WiMAX services. The antenna elements are based on circular curve-shaped monopoles having a compact area of 12 mm × 22 mm. The decoupling structure is an inverted L-shaped Defective Ground Structure (DGS, etched on the ring-shaped common ground plane, which acts as a bandstop filter. The presented MIMO design has a compact size of 34 mm × 34 mm. The reconfigurable frequency capability between the frequency bands of 3.3 - 3.7 GHz and the 4.4 - 5.7 GHz is achieved by switching the integrated Positive-Intrinsic-Negative (PIN) diodes between ON and OFF states. Simultaneously, the reconfigurable isolation ability between these bands is obtained by controlling the DGS decoupling elements' lengths by switching the incorporated PIN diodes between the OFF and ON states. The introduced decoupling structure accomplished good decoupling levels of 15 and 19 dB across the targeted frequency bands of WiMAX (3.4 – 3.6 GHz) and WLAN (5.15 – 5.35 GHz). The diversity ability of the MIMO configuration in terms of ECC and TARC is below 0.085 and -10 dB across both the operating bands.