Research On Electronically Reconfigurable Reflectionarray/Transmitarray Antennas

In the fields of satellite communications,such as space exploration and mobile communication,in order to adapt to the long-distance communication and relatively complicated space environment,it is essential to design high gain antennas.In recent years,reconfigurable reflectarray antennas(RRA)and reconfigurable transmitarray antennas(RTA)have been proposed.As a new generation of high-gain antennas,such antennas have the advantages of simple structure,easy conformality,easy fabrication,low cost and simple beam control.It can not only realize beam scanning quickly and flexibly,but also realize complex contoured beam and other functions.In this thesis,the RRA and RTA are studied in depth.The main contribution of this thesis is summarized as follows.1.Two kind of broadband RRAs are designed.Firstly,a broadband RRA with a single-layer multi-resonant element is proposed.The PIN diode is placed below the ground plane of the element,which not only facilitates the connection between the patch and the PIN diode,but also reduces the interference caused by the PIN diode and improves the aperture efficiency of the RRA.The element is able to implement two states by switching ON and OFF the diode.Simulated results show that the 3-d B gain bandwidth of the RRA is 18.3%,the peak aperture efficiency is 25%,and the beam scanning range can reach ±50°.Secondly,a 1-Bit broadband RRA with double-layer multi-resonant element is proposed.The antenna uses two square patches with different shapes to expand the bandwidth by forming two different resonance points.In addition,the thinner dielectric substrates are used to reduce dielectric loss without affecting the working bandwidth.Based on the proposed broadband element,a16×16 RRA at Ku-band is designed.Tested results show that the proposed RRA achieves 1-d B gain bandwidth of 22.5%,peak aperture efficiency of 25%,and beam scanning range of±60°.2.A new RTA is designed.Firstly,the gain bandwidth of the antenna is increased by designing a broadband transmitarray element.The element changes the polarization direction of the transmitted wave by switching the state of the PIN diode,and forms two opposite electric fields on the double-layer radiation patches.Based on the physical properties of the opposite electric field,the RTA element maintains 180° phase difference in a wider frequency range.Secondly,the phase optimization method of the RRA is used to reduce the phase errors and improve the radiation efficiency of the antenna.At the same time,based on the principle of polarization torsion,the DC bias line is designed as the polarization grid to control the polarization direction of electromagnetic waves,which effectively reduces the influence of the DC bias line on electromagnetic wave transmission.Simulated results show that the designed RTA can achieve the 2-D scanning range of ±40°.The peak gain of the antenna is 23.16 d Bi,the corresponding aperture efficiency is 24.1%,and its 1-d B gain bandwidth is 19.25%.The above results indicate that the antenna can effectively expand the bandwidth and achieve wide-angle beam scanning with higher efficiency.