2 × 2 MIMO antenna system with different antenna types for mobile terminals

Multiple-Input Multiple-Output (MIMO) is becoming very common and essential technology in mobile communications due to its great advantage of the downlink speed improvement; however the coupling effect between antenna elements in mobile phones deteriorates gain and correlation of MIMO. To solve the problem, many previous researches add a diversity of bars between antennas, but it requires valuable space of mobile phones. On the other hand, existing MIMO antenna systems usually use same type of antenna elements. In this letter, we present a novel MIMO antenna system for mobile phones, which highly increases gain and correlation of MIMO. It consists of not same antenna elements (e.g., two planar inverted-F antennas (PIFAs) but different antenna elements (e.g., one PIFA and one coupling antenna with the property of a loop). To validate the performance of our proposed antenna system, we develop its prototype and perform a diversity of experiments. Experimental results show that the isolation between antenna elements does not exceed −20 dB, ECC is smaller than 0.02 in all considered bands, and the average gain is reasonable. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1337–1340, 2016