Lens-corrected coaxial-groove horn for illuminating ultra wide area

Aperture antennas for satellite communications and radar systems require covering a desired area with a high gain and a low loss. When the coverage becomes much wider, horns are suitable as such antennas. Previously, we had developed multimode horns with coaxial grooves for a circular coverage. We had also proposed a dielectric-dome antenna achieving a wider illumination area up to ±70°. However, the aperture is large and also the dome is too heavy. For realizing a compact antenna to illuminate such a wide area, this paper proposes a lens-corrected multimode horn with a coaxial groove and a doughnut-shaped lens that is different from conventional lens-corrected horns with a simple pencil-beam. The aperture-field distribution for shaping the radiation pattern is determined by directivity synthesis based on the phase-retrieval method. As design examples, we present lens-corrected coaxial-groove horn antennas at 24 GHz. Their usefulness is verified by numerical and experimental evaluation for the fabricated antenna.