Two-Port Same-Polarized Patch Antenna Based on Two Out-of-Phase TM10 Modes for Access-Point MIMO Antenna Application

Abstract

A new two-port same-polarized rectangular patch antenna based on generating two out-of-phase TM₁₀ modes for multiple-input–multiple-output (MIMO) access-point antenna application is proposed. Two simple probe feeds located at two opposite positions along the resonant direction of the TM₁₀ mode modify the excited electric field distribution inside the resonant cavity such that the zero or very weak electric field excited by the first probe feed occurs in the close proximity of the second probe feed. This behavior leads to good port isolation. A design example of the proposed antenna in the fifth-generation band of 3.4−3.8\xa0GHz shows the excitation of two out-of-phase TM₁₀ modes with impedance matching <italic>S</italic>₁₁ (<italic>S</italic>₂₂) lower than −25\xa0dB, port isolation <italic>S</italic>₁₂ lower than −15 dB, envelope correlation coefficient less than 0.02, and antenna efficiency larger than 92%. An additional method of placing a conducting block on the ground plane and below the patch center to finely adjust the <italic>S</italic>₁₂ to have a much lower value is also studied.