Design of a Planar Array of Low Profile Horns at 28 GHz

Abstract

A planar array of low profile horns fed by a transverse slotted waveguide array in the low millimeter-wave regime (28 GHz) is presented. The array of transverse slots cannot be directly used as antenna as it has grating lobes due to the fact that slot elements must be spaced a guided wavelength. However, these slots can be transformed into low profile horns that with their radiation patterns attenuate the grating lobes. To this aim, low profile horns with less than 0.6λ0 height were designed. The horns include a couple of chips that contribute to further reduce the grating lobes especially in the H-plane. The good performance of the designed array was demonstrated by both simulations and experiments performed on a manufactured prototype. A 5 × 5 array was designed that has a measured realized gain of 26.6 dBi with a bandwidth below 2%, still useful for some applications such as some radar systems. The total electrical size of the array is 6.63λ0× 6.63λ0. The radiation efficiency is very high and the aperture efficiency is above 80%. This all-metal solution is advantageous for millimeter-wave applications where losses sustained by dielectric materials become severe and it can be easily scaled to higher frequencies.

High gain low profile horn array with circular polarization using a 3D printed anisotropic dielectric composite material at 38 GHz

“…In terms of radiation pattern, the maximum gain is not affected by the use of the polarizer, while the grating lobes are bigger than expected due to unwanted scattering produced by the polarizer. However, these values remains under the 12 dB of attenuation considered in most of the previous works regarding this type of antenna 8,31 .…”

“…To this aim, a single low-profile pyramidal horn has to be first designed and optimized following some guidelines from Refs. 30 , 31 . The objective is to have a high-aperture efficiency in each single element of the array by exciting two modes of the horn.…”