Study On Transmitarray Antenna And Its Beam-Steering Technology

Transmitarray antenna（TA）,as a kind of high-gain antenna,combines the characteristics of lens antenna and array antenna.TA has the advantages of a simple overall structure,flexible and controllable beam,and no complex feed network.Recently,TA has received lots of attention because of its wide range of applications,including long-distance wireless communication and radar detection.In this thesis,combined with the development requirements of high gain and beam-steering antenna in the current wireless communication system,the problems of narrow beam scanning range,high complexity,narrow working bandwidth,and high array profile of TA are studied.Therefore,the purposes of this thesis are to explore a novel TA element and its array beam-steering technology,a design concept of beam scanning TA based on lens-loaded elements,and a 1-bit dual-beam TA based on metasurface（MS）elements are proposed respectively.The main research work of this thesis is as follows:1.Study on the problems of narrow beam scanning range and high complexity of TA,a design concept of wide-angle beam scanning TA based on the lens-loaded element is proposed through the hybrid element technology.Firstly,the multiplexing of phase shifters（PSs）is realized by combining the receiving layer patches to form a 2×2 subarray,which can eliminate the use of 75%of the number of PSs compared to the traditional beam scanning TA design.Secondly,the lens is excited by multiple radiation patches in different positions of the radiation layer,which can realize wide-angle beam scanning by sub-area coverage with stable array antenna gain.Finally,a group of lens-loaded passive TAs was designed,fabricated,and measured using the above TA elements to verify the proposed design concept.The experimental results show that the designed TA obtains a maximum gain of 23.8d Bi at12.5GHz in the broadside direction,and the corresponding aperture efficiency is 34.1%.The1-d B and 3-d B gain bandwidths are 3.2%（12.2～12.6GHz）and 7.2%（12.0～12.9GHz）respectively,and within the beam scanning range of±60°,the maximum gain loss is less than 3.5d B.2.Study on the problems of narrow bandwidth and high profile of TA,a 1-bit dual-beam TA based on MS is proposed.Firstly,two orthogonal slots are designed in the metal of the receiving layer and the radiating layer,the metals on the two layers can be mutual ground and their polarizations are orthogonal.This design can avoid the mutual influence of the upper and lower metal while realizing the polarization rotation characteristic.Secondly,the transmission amplitude of the polarization rotation element is improved by connecting the two layers of reception and radiation with via,where the 1-d B transmission amplitude at14.0～19.1GHz is obtained.Meanwhile,two phase-states of 0°and 180°are achieved by rotating the upper metal.Further,a 20×20 scale wideband TA was designed,fabricated,and measured by the proposed TA element to verify the effectiveness of the design.The experimental results show that the single-beam TA has a 3-d B gain bandwidth of 35.4%（14.2～20.3GHz）,and achieves a peak gain of 22.3d Bi at 18.6GHz.Finally,a single-feed dual-beam TA is designed by the superposition of the array antenna aperture field.The array profile of TA is 0.055λ_16.5GHz,and only a single-layer dielectric substrate is used to achieve wideband characteristics and low-profile design.