Design and Analysis of a Wideband Multiple-Microstrip Dipole Antenna with High Isolation

Abstract

A wideband multiple-microstrip dipole antenna with dual polarization is proposed in this letter. The antenna consists of a radiator, a cross-shaped slot coupler, a pair of microstrip baluns, and a reflector. When baluns are excited, the cross-shaped slot coupler would work as a four-way equal-split power divider and generate four differential signals at four ends of the slotlines. Afterward, the signals would be coupled to four modified dipoles to radiate and synthesize slant ±45° linear polarizations. The proposed design is verified by the fabrication and testing of a prototype antenna. Measured results agree well with the simulated ones, giving a wide impedance bandwidth from 1.68 to 2.75 GHz, a high port-to-port isolation (better than 37 dB) within the operating frequency bandwidth, and a good radiation pattern. Besides, the proposed antenna maintains a compact structure measuring 0.78λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 0.78λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 0.18λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> .