Design of a Hollow Dielectric Loading for Wideband Gain Enhancement of a Horn Antenna

The far-field gain of commercial horn antennas primarily depends on aperture area and flare length. Traditionally, for every dBi of gain increment, the flare length should increase by 20% and the aperture area by 10%. External lens classes, such as gradient refractive index, concave, or Fresnel, are used to improve gain by <= 2 dBi, but at the cost of a volumetric increase by 75% in the range of 4.8-6 GHz. We propose a hollow dielectric loading (HDL) loaded in the flare section of the horn antenna. The shape and position of the HDL are optimized using an evolutionary algorithm to obtain the maximum gain from a conical corrugated horn antenna (CCHA) at boresight. The optimized design yielded a total volume 40% smaller than traditional horn while achieving 3.5 dBi peak gain improvement in the operating frequency range. We also observed an improvement in the electric field by 24% while retaining parity in the impedance bandwidth. A 3D-printed prototype of the optimized CCHA and the HDL is fabricated and measured. The measured and simulated results demonstrated good agreement with a maximum difference of 4%.