Gain and Radiation Pattern Enhancement of the H-Plane Horn Antenna Using a Tapered Dielectric Lens

Abstract

The design of a high-gain and low-profile $H$-plane horn antenna embedded into a large metallic platform is proposed. The antenna is composed of three parts: Coaxial-to-ridged transition, wideband $H$-plane antenna, and dielectric lens. The coaxial-to-ridged transition makes an efficient conversion from TEM modes in a coaxial probe to the fundamental TE10 mode in a ridged horn, and by choosing the ratio between horn aperture and length and suppressing the TE higher mode, the optimal design of the $H$-plane horn antenna can be obtained. Then, a tapered dielectric lens is located in the end-fire direction, which converts the TE wave into the leaky-wave mode, enhancing the peak gain. A prototype of the proposed antenna is finally fabricated and tested. The measured results are in good agreement with the simulated ones, which show that the proposed antenna has a very wide bandwidth from 2.5 to 20 GHz for the voltage standing wave ratio (VSWR) < 2.5 and exhibits a low thickness of only 8 mm ( $0.066\lambda-{L}$ , $\lambda-{L}$ is the free-space wavelength at the lowest operating frequency). Good radiation pattern and high gain can be achieved over a wide frequency band.