Wideband Four-Port Single-Patch Antenna Based on the Quasi-TM1/2,1/2 Mode for 5G MIMO Access-Point Application

A wideband four-port single-patch antenna for fifth-generation (5G) MIMO access-point application in 3.3-5.0 GHz (41% centered at 4.15 GHz) is presented. The antenna uses a simple square patch of size 42 mm
$\times$
42 mm (
$0.58 \boldsymbol {\lambda } \times 0.58 \boldsymbol {\lambda } $
at 4.15 GHz) mounted 10 mm above a ground plane. To generate four isolated waves in a wide band for MIMO application, the square patch is short-circuited to the ground plane using four simple L-shape metal walls to form four resonant quadrants for the quasi-TM
_1/2,1/2
mode excitation. Each resonant quadrant is excited using a slot-coupled probe feed to have dual-resonance behavior with good impedance matching over a wide band. It is obtained that the single-patch antenna can generate four isolated waves in 3.3-5.0 GHz with impedance matching better than −10 dB, port isolation >15 dB, antenna efficiency >80%, and envelope correlation coefficients <0.03. Details of the proposed antenna are presented. An extended design for enhanced port isolation of the proposed antenna is also studied.