Gain Enhancement of Horn Antenna Using a Metal Lens

Abstract

A compact wideband open-horn antenna is proposed for point-to-point wireless communications. The antenna consists of a spatial power divider and an <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$H$ </tex-math></inline-formula> -plane lens. Both the power divider and lens are metallic, fabricated by using 3-D-printing technology. Our proposed lens has wrinkled subchannels of different lengths to convert the original quasi-cylindrical wavefront into a nearly planar wavefront across a wide frequency range, giving a wideband high-gain antenna. The operating principle and the design guideline are given. Using the guideline, two design examples with different <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$E$ </tex-math></inline-formula> -field magnitude distributions are studied and fabricated for Ku-band applications. The first design has a uniform <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$E$ </tex-math></inline-formula> -field magnitude distribution, with its maximum measured gain and normalized sidelobe level (SLL) being 18.1 dBi and −9.4 dB, respectively. The second design has a tapered <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$E$ </tex-math></inline-formula> -field magnitude distribution. In this case, the maximum measured gain and normalized SLL are 19.6 dBi and −15.0 dB, respectively. The overall measured 3-dB gain bandwidths of the two designs are more than 46.7%. It is found that the sizes (axial lengths) of the proposed designs are smaller than those of optimum horn antennas by more than 60%.