Four-Port Multiband MIMO Filtenna with an Isolation Filter for Sub-6 GHz 5G Applications

In this paper, a four-port multiple-input-multiple-output (MIMO) filtenna (antenna with filter) system with isolation enhancing band-reject filter (BRF) is presented. The filtenna system is designed by integrating a multi-functional filter (MFF) in the antenna’s feed line. The MFF has two modes of operation. In its 1
^st
mode, the filtenna system acts as a dualband antenna in the frequency range of 2.3-4.5 GHz and 5.3-5.5 GHz. While, in the 2
^nd
mode, it acts as a single band antenna in the frequency range 3.3-4.1 GHz. To improve the isolation between the antenna elements, an open stub line (OSL) based BRF has been incorporated in the ground plane of the filtenna system. The overall design is integrated into a Rogers RO 4003C substrate (ε
r
=3.55, tanδ=0.0031) of dimension 100×65×1.52 mm
³
. The designed antenna system is suitable for sub-6 GHz fifth-generation (5G) systems.