Four-port MIMO antenna loaded with FSS in FR2 band for wireless applications

This work reports a four-port MIMO antenna integrated with a novel wideband frequency-selective surface (FSS). The proposed MIMO antenna is fabricated on Rogers-dielectric with permittivity 2.20 and thickness of 0.254 mm with an overall area of 30 × 36 mm². The radiating patch is achieved by merging three ring-hexagonal geometries, which are fed by an asymmetric tapered transmission line with a partial-rectangular ground printed on another surface with a pair of rectangular slots and an open-ended slot beneath the feedline. A novel de-coupling structure achieves isolation of more than 10.0 dB in MIMO configuration with a pair of radiating elements placed mirrored-adjacent sequence and the other pair placed oppositely. A novel 7 × 7 frequency-selective-surface of dimension 56 mm × 56 mm with an operating bandwidth of 10-43.30 GHz is also fabricated on the same substrate as an antenna and is placed 10.0 mm apart from the MIMO-antenna, which enhances the average peak-realized-gain by 8.0 dBi. The MIMO antenna achieves - 10.0 dB bandwidth of 3.45-7.25 GHz (Band-A) and 19.70-82.10 GHz (Band-B). The MIMO-FSS antenna achieves better diversity parameter with ECC_M-FSS[Formula: see text] 0.02 (Band-A), 0.01 (Band-B), DG_M-FSS[Formula: see text] 9.998dB (Band-A), 9.996 dB (Band-B), TARC_M-FSS[Formula: see text] - 4.0 dB (Band-A), - 6.0 dB (Band-B), CCL_M-FSS[Formula: see text]0.18 b/s/Hz (Band-A), 0.25 b/s/Hz (Band-B), MEG_M-FSS[Formula: see text] - 3.0 dB (Band-A and Band-B), and MEG (port_a-port_a)[Formula: see text]0.0 dB (Band-A and Band-B). The SAR_M-FSS values at 3.50 GHz, 5.90 GHz, 24.0 GHz, 28.0 GHz, 38.0 GHz, 39.0 GHz, 41.0 GHz, 43.0 GHz, 47.0 GHz and 60.0 GHz are below threshold value of 1.60 W/Kg at 1 g of the tissue. The bending analysis at 15°, 30°, and 45° of the MIMO-FSS antenna matches the - 10.0 dB bandwidth at 0-degree bending, suggesting application in flexible electronics. The antenna also maintains stable 2D radiation patterns in principal planes at a lower frequency of 3.50 GHz & 5.90 GHz, and is acceptable in the remaining higher frequency application bands. The MIMO proposed antenna loaded with FSS also records the enhancement of peak realized gain by 5.85 dBi in Band 2.