REVIEW ARTICLE Design of a dual-band MIMO dielectric resonator antenna with high port isolation for WiMAX and WLAN applications Aftab Ahmad Khan 1 | Rizwan Khan 1 | Sajid Aqeel 1 | Jamal Nasir 1,2 | Jawad Saleem 1 | Owais 1 1 COMSATS Institute of Information Technology, Abbottabad, Pakistan 2 Faculty of Electrical Engineering, Wireless Communication Centre (WCC) Universiti Teknologi Malaysia, Johor Bahru, Malaysia Correspondence Aftab Ahmad Khan, COMSATS Institute of Information Technology, Abbottabad, Pakistan. Email: aftabjadoon@ciit.net.pk Abstract A novel dual-band MIMO dielectric resonator antenna with high port isolation for WiMAX and WLAN applications is designed and investigated. The proposed antenna operates at 3.5 and 5.25 GHz bands. High port isolation is achieved using hybrid feeding mechanism that excites two orthogonal modes at each frequency bands. The measured impedance bandwidth of the proposed antenna covers the entire WiMAX (3.4–3.7) GHz and WLAN (5.15–5.35) GHz bands. The scalable behavior along with the frequency ratio of the antenna has also been investigated in this work. The measured isolation between antenna ports is 252 dB at the lower band and 246 dB at the upper band, respectively. Envelope correlation coefficient, diversity gain and mean effective gain have also been investigated. Moreover, measured results are in good agreement with the simulated ones. KEYWORDS dielectric resonator antenna, envelop correlation coefficient, mean effective gain, mul- tiple input multiple outputs 1 | INTRODUCTION Worldwide interoperability for microwave access (WiMAX) and Wireless local area network (WLAN) have gained a pre- dominant importance in multiple input multiple output (MIMO) applications due to high-speed connectivity between laptops, cell phones, and other communication devices. In MIMO system, multiple antennas are used at both transmitter and receiver to improve reliability and capacity of the system without adding extra power or spec- trum. 1 In order to design multiple antennas, the challenging task is the mutual coupling between antenna elements, as it increases the correlation and deteriorates the performance of the system. 2 In microstrip patch antennas (MPAs), numerous methods have been presented for single-band 3–5 and dual-band anten- nas 6,7 to reduce mutual coupling between antenna ports. These methods include defected ground structure, neutraliza- tion line, eigenmode decoupling and capacitively loaded loops. At high frequencies, metallic antennas suffer from low radiation efficiency and bandwidth. Dielectric resonator antennas (DRAs) are better alternatives for both mobile handset and wireless communication applications due to small size, high radiation efficiency, wide impedance band- width, low cost and negligible losses at higher frequencies. 8 DRAs are 3-dimensional structures offering one more degree of freedom that allows a variety of excitation methods with orthogonal polarizations. There are only a few investigations on dual-band DRAs for MIMO applications. 9–12 In Ref. 9, a dual-band cylindrical DRA for MIMO LTE terminal is presented where orthogonal excitation schemes have been used to achieve 235 dB for the first band and 222 dB isolation for the second band. Authors in Ref. 10 proposed a compact and multiband DRA in which printed line has been used to achieve a resonance at 800 MHz, however, isolation is very poor at this band. A dual-band and wide-band dual-polarized cylindrical DRA is presented in Ref. 11 in which authors achieved 236 dB and -37 dB isolation using strip and slot fed excitation methods for port 1 and port 2, respectively. But in this design, the Int. J. RF Microw. Comput. Aided Eng. 2016; 1-11 wileyonlinelibrary.com/journal/mmce V C 2016 Wiley Periodicals, Inc. | 1 Received: 11 June 2016 | Revised: 27 September 2016 | Accepted: 27 September 2016 DOI 10.1002/mmce.21058