Study And Design Of Tunable Reflectarray Antennas Based On Liquid Crystal

Reconfigurable reflectarray antennas have benefited from increased attention in the recent past, since they combine some advantages of reflectors and array antennas, such as high gain, strong directivity, small volumes and light weight. Compared with microstrip reflectarrays, the reflectarray antennas based on liquid crystals (LC) can be used for beam reconfiguration or beam scanning through the inclusion of phase-shifter devices that change the phase of reflected field as a function of control signals applied to them.Liquid crystal material in high operating frequency can still achieve high turning rate with wide band. So the study of reflectarray antennas based on LC for space exploration, terahertz communication and so on, has important significance. Researches on the analysis of the reflectarray elements and arrays have been done in this thesis.A Ku band microstrip reflectarray antenna has been designed, and the gain of the reflectarray antenna is 20dB when the antenna in a direction of 30°. To assess the reconfigurability with LC phase shift, different unit cells have been realized and analyzed using CST, showing good performance. Based on this unit cell a reflectarray with beamsteering capability has been designed and realized. The simulations demonstrate that the maximum scanning angle is 30° over a 4.9% bandwidth (336GHz-353GHz) in the low THz range by optimizing the unit cell geometry.