A Planar Huygens Antenna Utilizing Crossed Electric and Magnetic Dipoles

TL;DR

This paper presents a planar Huygens antenna using crossed electric and magnetic dipoles that achieves high directivity and gain at 4.5 GHz, offering a low-profile, PCB-compatible design with improved efficiency over traditional small-loop magnetic dipoles.

Contribution

It introduces a novel magnetic dipole source with a 0.5lambda slot near a doubled-length electric dipole, resulting in a highly directive, high-gain antenna with simple feeding and PCB compatibility.

Findings

Achieves up to 8.37 dBi directivity at 4.5 GHz

Demonstrates full agreement between analytical, numerical, and measured results

Offers a low-profile, low-complexity design suitable for high-gain applications

Abstract

The natural source of a magnetic dipole in antennas is typically an electrically small loop, which can be utilized in conjunction with an electric dipole to realize an electrically small Huygens' antenna. However, these antennas suffer from low radiation efficiency and their theoretical directivity limit is 4.8 dBi. Magnetic dipoles with an electrical size larger than 0.5lambda are highly desirable for high-gain applications. This paper builds on the development of a magnetic dipole source that utilizes a 0.5lambda slot positioned near a printed dipole with a length twice that of the slot. Such a combination of electric and magnetic dipoles yields a highly directive radiation pattern, resulting in a higher gain than a uniformly illuminated antenna of similar size. The prototype is designed to operate at 4.5 GHz, with a directivity of up to 8.37 dBi. The analytical, numerical, and measured results agree fully. This high-gain superdirective antenna is highly desirable due to its excellent features, including being low-profile, PCB compatible, and having a low-complexity feeding topology, compared to the existing approach of the two-element end-fire array.