Compact, Highly Efficient Huygens Antenna Array With Low Sidelobe and Backlobe Levels

An innovative Huygens antenna array is reported. It has a compact cross section and simultaneously exhibits high aperture and radiation efficiencies and low sidelobe level (SLL) and backlobe level. The fundamental system consists of a collinear
$1 \times 4$
magnetic dipole (MD) array unified with an in-phase collinear
$1 \times 4$
electric dipole (ED) array. The MD array is realized as TE
_0.5.0
-mode SIW waveguide sections with seamlessly integrated phase inverters. The ED array is accomplished with two metal plates orthogonally connected to the waveguide aperture. Low sidelobes are realized, thanks to a natural magnitude taper of the fields radiated by each Huygens section located further from the waveguide center where its excitation resides. This fundamental array is easily expanded to a
$4\,\times \,4$
array facilitated by an amplitude-weighted 1-to-4 microstrip feed network. An X-band prototype operating at 10 GHz was fabricated and tested. The measured and simulated results are in very good agreement. The measured
$\vert \text{S}_{11} \vert $
bandwidth is 570 MHz from 9.63 to 10.2 GHz. The measured realized gain is stable across the entire bandwidth with a 17.5 dBi peak value. All measured SLL and backlobe levels are less than −20 dB. The measured realized aperture efficiency is 67.0% and the simulated radiation efficiency reaches 92%.