Design Of Low Profile Resonant Cavity Antannas And Reconfigurable Transmitarray Antennas

With the rapid development of modern wireless communication technology,various radios systems have increasingly higher requirements for the antennas.High gain antennas have always been one of the research hotspots.Fabry-Pérot(FP)resonant cavity antenna and reconfigurable transmitarray antennas(RTA)have many advantages,such as small size,low cost,light weight,scanning beam,and high gain without needing complex feeding networks necessary for the conventional antenna arrays.Being closely related the research projects,this thesis conducts in-depth research on the designing low-profile FP resonator cavity antennas and broadband RTA.The main contributions of this thesis can be summarized as follows.1.A low-profile dual-band dual-polarization FP resonant cavity antenna is presented.Firstly,a partially reflective surface(PRS)structure with larger positive phase gradient versus increasing frequency is proposed to achieve the dual-band characteristics with a small frequency ratio.Then,the electromagnetic band gap(EBG)structure is adopted as the reflection plane to reduce the profile of FP resonant cavity antenna.A rectangular microstrip patch antenna integrated into center of the EBG structure is used as a dual-band and dualpolarization feed for the FP resonant cavity antenna,The designed PRS structure and EBG structure are applied to the resonant cavity antenna operating in the satellite communication frequency band.Compared with the traditional dual-band design method,the proposed FP resonant cavity antenna with only one cavity is suitable for the dual-band operation with small frequency ratio.The measurement results demonstrate that the proposed FPRA has peak gains of 14.3 d Bi with the horizontal polarization at 12.4 GHz and 16.8 d Bi with vertical polarization at 14.1 GHz.Moreover,the measured 3 d B gain bandwidths in the lower and higher bands are 7.3% and 3.6%,respectively,which cover the receiving and transmitting bands of satellite communication in the Ku band.2.A broadband 1-bit RTA based on the polarization rotation element is proposed.In the element the polarization rotating surface is used as the phase shift,and the PIN diodes are soldered in center of the polarization rotating surface.By controlling the PIN diodes in the ON and OFF states,the polarization orientation of the wave emitted by the RTA element is changed.Based on the physical properties of the opposite electric field,broadband 180°phase differences are formed between the outgoing waves in the two states.For the first time,the polarizer grids are used instead of DC bias lines to avoid the blocking effect,and improve the radiation efficiency of the RTA effectively.A 16×16 unit transmission array antenna is designed and fabricated.Experimental results show that its 3 d B and 1 d B gain bandwidths are 45% and 17%,respectively.Its peak gain is 16.8 d Bi with radiation efficiency of 18.4%.By coding the phase distribution of the transmission plane,the proposed RTA has good beam scanning performance with 2-D scanning range of ±40°.