Analysis of the Transmission Performance Limits for a Multi-layer Transmitarray Unit Cell

This communication presents a theoretical study that establishes the performance limits for a multi-layer transmitarray unit cell. This is the first study to be applicable to unit cells in which the conducting resonators, on the different layers, are shaped differently. A theoretical calculation is derived at the beginning. The theoretical calculations predict that, for an S21 amplitude of -1 dB, unit cells having two and three conducting layers provide a phase shifting range of 170° and 360°, respectively. Additionally, for a given phase shifting range of S21, a new methodology for analyzing the maximum S21 amplitude, based on different substrates, is proposed. For the first time, we prove that it is efficient to attain the maximum S21 amplitudes by employing a smaller substrate permittivity or a quarter-of-wavelength substrate electrical thickness. Finally, the theoretical calculations have been validated through computer simulation

Wideband Frequency Selective Surface Based Transmitarray Antenna at X-Band

In this paper, a wideband multilayer transmitarray antenna is designed for Ku frequency band. The unit cell is designed at 12GHz using frequency selective surface structure. Double square ring with center patch based multilayer unit cell is simulated. The effect of substrate thickness variation on transmission coefficient magnitude and phase range is discussed. The horn antenna designed at X-band will be used as feed source for transmitarray antenna. Transmitarray simulation results show wide impedance bandwidth from 10 to 13GHz. Wide gain bandwidth of 1.975GHz with peak gain of 18.96dB is achieved. The proposed transmitarray design will find applications in high gain, directional, low profile antennas for X-band communication systems

Wideband Transmitarray Antenna Using Compact 2-Bit Filtering Unit Cells

A wideband transmitarray (TA) antenna using compact 2-bit filtering unit cells is presented with the center frequency designed at 10 GHz. The presented TA antenna features wide bandwidth with a compact aperture size, filtering radiation performance, and low cross-polarization levels. A novel compact 2-bit phasing scheme is first proposed and illustrated by utilizing the resonating characteristics of resonators. Charging and discharging principle of a resonator is utilized to realize a 180° phase shift, while J-invertor originating from the coupling between resonators is utilized to realize a 90° phase shift. Based on the proposed phasing scheme, novel 2-bit compact filtering unit cells are designed with a compact four-copper-layer configuration. Finally, a high-gain TA antenna was designed, fabricated, and measured for radiation performance verification. Owing to the elaborately designed unit cells and the cut-off effect of the feed horn, a filtering radiation performance with flat in-band gain and high out-of-band suppressions is obtained. Measured results show that a flat 3dB gain bandwidth of 21.3% is achieved with a thin thickness of 0.11λ 0 . High suppressions of 34.3 dB and 30.1 dB are measured over the lower and upper out-of-bands. In addition, a low cross-polarization level of -38.5 dB is obtained for high-quality wireless communications