A wideband transmitarray using triple-layer elements with reduced profile

Abstract

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%.

Near-field focused planar transmitarray with low profile design for microwave power transmission

“…5. The transmission phase curves are parallel, indicating that the transmitarray unit cell can achieve a broadband response [15]. When the electromagnetic wave emitted from the feed source reaches the transmitarray, the incidence angle of most of the unit cells is not perpendicular.…”

“…This can cause problems such as an increase in profile height as well as an increase in weight. In [15], a 360° phase change with a profile of 0.15λ is achieved using three dielectric substrates and three metal layers, but the inconsistency of metal layer structure introduced more optimization variables, which increased the difficulty of design. To further reduce the profile of the transmitarray unit cell, in some designs, unit cells with discrete phase states [16,17,18,19] are used to form the transmitarray antenna, but this reduces the overall antenna performance.…”