Wideband Unit-Cell Design For X-band Transmitarray

This paper presents in detail the design of a wideband unit-cell for X-band passive transmitarray. The unit-cell is based on multi-layer structure and consists of four conducting layers printed on two identical substrates. A set of eight unit-cells are optimized to cover full 360° phase range and to obtain eight transmission phase states with a step of 45° for a common -3 dB bandwidth of 2.0 GHz. To evaluate the performance of the proposed unit-cell, a transmitarray antenna is designed and simulated at X-band. The simulated results show that the transmitarray provides maximum gain of 23.6 dBi, corresponding to a high aperture efficiency of 38.0%.