Design and characterization of 2-bit passive unit-cells and transmit-arrays in X-band

This paper deals with a 2-bit phase quantization (0°/90°/180°/270°) unit-cell for passive transmit-array applications at 10 GHz. The unit-cell consists of a single ground plane, two identical substrates, and two rectangular patch antennas connected by a metallized via hole. We first present the architecture of the unit-cell and an equivalent lumped-element circuit model based on analytic formulas. Their performance is also evaluated by full-wave simulations. To validate the operation principle, several unit-cell prototypes have been manufactured and tested in a waveguide simulator. Finally, one-dimensional beam-steering using 20×20 unit-cells transmit-arrays is demonstrated in linear- and circular-polarization.