A Quad-Port MIMO Antenna With Improved Isolation Developed by Colored Resin Fiber Material for Wideband Applications

The article explores a quad-port compact (56 x 56 x 1.5 mm(3)) multiple-input multiple-output (MIMO) antenna developed on a colored resin fiber material encompassing enhanced isolation for wideband applications. The design antenna configuration incorporates four ground stubs positioned among antenna pairs on the upper section of the substrate and eight rectangular-shaped ground slots to enhance antenna isolation. The antenna functions over a broad spectral range from 4.21 to 10.95 GHz, providing coverage for WLAN (5.15-5.35 GHz/5.725-5.825 GHz), C band uplink (5.925-6.425 GHz), downlink defense (7.2-7.7 GHz), and ITU band (8-8.5 GHz), with 88.91% fractional bandwidth. The antenna design ensures exceptional isolation, exceeding 21 dB among orthogonal antennas and 25 dB between oppositely placed antennas across the entire functioning bandwidth. Across the working band, the antenna showcases favorable diversity characteristics, including a lower envelope correlation coefficient (ECC < 0.085), higher diversity gain (DG > 9.95 dB), minimal channel capacity loss (< 0.39 bits/s/Hz), and negligible magnitude variation in mean effective gain among the antenna ports (< 0.1 dB). The acquired total active reflection (TARC) curve exhibits the antenna's robust resonance features over the application band and commendable time domain properties in the active spectral region. The findings of the simulation and measurements revealed a close alignment.