Wideband Conformal Transmitarray Employing Tightly Coupled Huygens Element at E Band

A new method to achieve wideband conformal transmitarrays is presented by employing tightly coupled Huygens element in this paper. The element is composed of five pairs of metallic strips which are printed on two sides of a dielectric substrate. The tightly coupled elements can achieve a high transmission and a nearly full phase coverage in a wide bandwidth from 71 to 87 GHz. To further analyze the element, equivalent circuit models are developed. Good agreement is achieved between circuit and full-wave simulations. A cylindrical conformal transmitarray at 78 GHz is designed, fabricated and measured. The measured results have good agreement with the simulated ones. The measured peak realized gain is 26.6 dBi with an aperture efficiency of 37.2%. The measured 3-dB gain bandwidth is 20.4% from 71 to 87 GHz, which can fully cover the E-band spectrum.