NOVEL COMPACT AND DUAL-BROADBAND MICROSTRIP MIMO ANTENNAS FOR WIRELESS APPLICATIONS

Two novel microstrip MIMO antennas have been proposed and presented in this paper. The objective is to design a compact and dual-broadband MIMO antenna module appropriate for many wireless devices including WLAN, LTE and WiMax. The presented MIMO antennas have been analyzed, designed, simulated and investigated using CST MW simulator. They have been fabricated (FR-4 substrate), and their scattering matrices and total efficiencies have been measured. The first MIMO antenna module is composed of four proposed broadband microstrip antennas arranged in two MIMO antenna pairs. The first MIMO pair resonates at 5.2GHz (5.08–5.313 GHz) while the second pair resonates at 5.8GHz (5.643–5.96 GHz). This MIMO antenna has a compact size of 40× 40mm2, dualbroadband, minimum mutual coupling below −25 dB, bandwidth greater than 225MHz and gain of 3.8 dBi. The second MIMO antenna module consists of two proposed and modified dual-broadband microstrip monopole antennas, where, each has a dual resonance at 3.7GHz (3.46–3.94 GHz) and 5.2GHz (4.99–5.41 GHz). This MIMO antenna has an overall compact size of 20 × 50mm2, minimum coupling below −22 dB, bandwidth greater than 425MHz and gain of 2.5 dBi. Good agreement has been achieved between measured and simulated results. The proposed MIMO antennas cover many wireless applications with the following specifications: compact size, dual-broadband, moderate gain, good efficiency and high port-to-port isolation.