A Wideband, 1 bit Transmitarray Antenna Design With Flat Gain Response
Sen Liu, Hiroyasu Sato, Qiang Chen
Abstract
A wideband transmitarray antenna exploiting 1 bit polarization-rotation unit cell is proposed in this article. A printed antipodal fermi tapered slot antenna is introduced as the source feed. Considering the radiation characteristics of the source feed, system-level performances in terms of spillover, illumination, and aperture efficiencies are analyzed, revealing the inherent restriction of wideband operation. In order to obtain wideband performance, a novel three-layer polarization-rotation 1 bit unit cell is developed to introduce phase errors over the aperture, which act as one kind of degree-of-freedom during the system design. An optimization method is employed to further balance the overall phase errors experienced over a wide frequency band, resulting in a flat gain response. To verify the design concept, a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$13\times 17$ </tex-math></inline-formula> -element ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$195\,\, \text {mm}\times 255 \,\,\text {mm}$ </tex-math></inline-formula> ) antenna prototype is fabricated and measured with a realized gain of 22.5 dBi at 10 GHz and 1 dB fractional gain bandwidth of 37% achieved, demonstrating great potentials in many communication applications.