Wideband Horn Antenna With Integrated Conformal Metal Lens

A physics-based approach is used to study the conformal-lens integrated horn antenna. The conformal metal lens is obtained by bending the top face of the horn antenna. It is designed in such a way that different paths from the feed point of the horn to the radiation aperture have the same length and hence the same phase. As a result, a uniform phase can be obtained across the radiation aperture to increase the antenna gain. Our first design has a compact size of
$4.7\lambda _{0}$
at 21.5 GHz, where
$\lambda _{0}$
is the wavelength in air. It has an aperture efficiency of 80% and a −10-dB impedance bandwidth of 22.6% (19.1–23.9 GHz). It is a basic design with no matching parts. To widen the bandwidth, a second design is investigated. It is obtained by modifying the conformal surface and introducing a matching structure at the radiation aperture. To verify the idea, a prototype was fabricated and tested. It has an axial length of
$9.7\lambda _{0}$
and a flare angle of 60° at 35 GHz. Good agreement between the measured and simulated results is obtained. Our design has a very wide measured −10-dB impedance bandwidth of 123.0% (14.3–60.0 GHz). It has a measured 3-dB gain bandwidth of 54.6% (31.7–55.5 GHz), with the maximum measured gain given by 21.7 dBi. Its gain is 5 dB higher than that of a conventional horn antenna with the same axial length of
$9.7\lambda _{0}$
and flare angle of 60°.