A Printed Balun-Fed Dipole Antenna and Its Simple Design for Dual-Polarized Operations

This paper presents comprehensive study on a novel compact balun-fed dipole antenna (BFDA) and its simple PCB design for dual-polarized operations. Unlike conventional printed baluns that only function as feed transitions, the proposed embedded balun is electromagnetically coupled to the radiators and actively participates in the resonance formation and bandwidth enhancement. The antenna integrates a balun-based feed with printed dipole patches through connecting vias, enabling a compact form factor, wide impedance bandwidth, and promising radiation performance. The working principle of the balun-embedded feed and its effects on impedance bandwidth, port isolation, and polarization purity is provided. For dual-polarized operations, two orthogonally oriented BFDAs are simply co-located within the same aperture, achieving a very miniature area without compromising the isolation. The fabricated prototype exhibits a port-to-port isolation exceeding 40 dB across 12 GHz to 15 GHz. The impedance bandwidth is above 23% under a compact antenna volume of 0.36λ0× 0.36λ0× 0.09λ0. The measured radiation patterns exhibit stable and broadband characteristics, where the co-polarization levels have a good agreement with simulations while some discrepancies for the cross-polarization levels are observed. A figure of merit (FoM) that combines antenna volume, impedance bandwidth, and port isolation is introduced to facilitate comparison among dual-polarized antennas with similar design objectives. These results demonstrate that the presented antenna has great practical potential for space-constrained, high-performance, and cost-effective wireless applications.