Platform Integrated Multiband MIMO Antennas for 5G Mobile Communications
Hui Li, Jinbo Yu, Yunze Diao, Kexin Liu
Abstract
To fulfil different requirements in complex wireless communication scenarios for internet of things (IoT), terminal devices enabled with multiband and MIMO antennas are in demand. In this article, a method for designing multiband and multiport platform integrated terminal antennas is proposed using <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> -port characteristic mode (CM) approach. An example of handset antenna system is taken to illustrate the design procedure. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> ports are firstly added along the handset, leading to a <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> × <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> impedance matrix. The status of the ports, i.e., short or open, is optimized based on the modal significances of the sub-impedance matrix at the target bands. Consequently, the optimized structure, with proper locations of breakings and groundings along the frames, is obtained. The feedings of the antennas are then selected from the grounding points based on the local modal currents of the desired modes. At the same time, low correlations between MIMO antennas are ensured by selecting the least correlated ports. As a result, six antennas are designed on the mobile handset, with two antennas covering the cellular bands of GSM900 (880–960 MHz) and DCS1800 (1710–1900 MHz) and other four antennas operating at the 5G bands of 2500-2690 MHz and 3300-3600 MHz. The proposed method is also applied to a transparent vehicular antenna for low profile and dual-band operations, showing its wide application to different terminal antennas.