A wideband transmitarray using triple-layer elements with reduced profile

A triple-layer wideband transmitarray (TA) which works at 18.5 GHz with reduced profile is presented in this paper. The unit cell composed of three metal layers, each layer is etched on the corresponding dielectric substrate. The top layer consists of double square rings, the same as the bottom layer. The intermediate layer consists of a Jerusalem cross slot. The thickness of designed unit cell is 0.15λ, where λ is the wavelength in free-space. A large frequency range is implemented by parallel sets of phase curves generated by proposed unit cell. The magnitude of transmission coefficient is less than 1 dB and the phase shift range exceeds 360 degree across the entire frequency range. We design, fabricate and measure a TA operating at 18.5 GHz to show the validation of this paper. Through the measurement, we can obtain that the 1-dB gain bandwidth is 14.8% (17.5–20.3 GHz), and maximum gain is 22.5 dB at 18.5 GHz. The proposed transmitarray’s maximum aperture efficiency is 46%.