| In recent years,the technical requirements for spaceborne antennas in the fields of communication,radar,navigation and detection are increasing with the rapid popularization of satellite payload applications.On one hand,the antenna is required to possess excellent electrical properties such as high gain,high efficiency and beam scanning ability.On the other hand,the antenna is also desired to be low profile,light weight and high integration,so as to obtain the maximum benefit at the lowest price of the volume and weight occupation of the satellite payload.Reflector antennas and array antennas are two commonly used forms of spaceborne high-gain antennas,which are becoming more and more mature after years of development.However,the payloads represented by high-throughput satellites and small satellites put forward more stringent requirements for satellite antennas with low cost,light weight,low profile,and easy deployment.Obviously,the traditional antennas are no longer fully competent.Therefore,it is necessary to carry out innovative designs on existing antenna forms or introduce new antenna types,such as reflectarray antennas,which are of important theoretical significance and application value for improving the technical capabilities of our country’s spaceborne antennas.The dissertation focuses on the research of new spaceborne array antennas.On the basis of exploring the frontier development directions of array antennas such as multi-beam antenna feed arrays,phased array antennas,and reflectrray antennas,the dissertation mainly focuses on the operation principle,theoretical research and engineering implementation of Tx/Rx duplexing array antenna,broadband reflectarray antenna and low profile reconfigurable reflectarray antenna.The innovative work of the paper can be summarized as follows:1.The multi-beam feed array technology based on the horn antenna and the technology of the shared phased array antenna for transmitting and receiving are studied,focusing on seeking breakthroughs in the highly integrated and compact design of horn antenna and the feed network with multi-frequency and multi-polarization channels.Firstly,a broadband orthogonal mode coupler based on symmetrical double-arm E-plane coupling,h-type ultra-wideband frequency duplexer and optical wall shaped horn are designed and cascaded into a feed chain to cover Ku＿FSS(Fixed Satellite Service)frequency band(10.7GHz～14.5GHz),which integrates four channels to realize the dual-frequency and dual-linear-polarization multiplexing.At the same time,the designed unit cell meets the array spacing requirement of the multi-beam antenna feed array,which can be utilized to effectively improve the communication capacity of the whole satellite payload.Secondly,a unit cell of Tx/Rx duplexing phased array which can be used in K / Ka-band satellite communication system is innovatively proposed.The unit works with dual frequency and dual circular polarization with the advantages of high gain and high channel isolation.The unit is composed of broadband horn antenna and waveguide feed network to realize the integration of two orthogonal circular polarization channels in Ka band and two different sub-band channels in K band.The transverse envelope of the element is 23 mm,which is optimal compared with works of the known literatures.Finally,based on the K/Ka-band phased array unit,an architecture of Tx/Rx duplexing phased array antenna is proposed.The architecture simplifies the complexity of T/R networks and realizes low mutual coupling,low loss,high isolation and good reliability of phased array.The simulated and measured results show that beam scanning range the array is ±20° and ±18° in K and Ka frequency bands,respectively,which meets the global beam coverage requirements of synchronous orbit satellites.The measured aperture efficiency of the prototype is greater than 71% and 61% at 20 GHz and 30 GHz respectively,the isolation of different frequency channels is greater than 50 d B,and the isolation of different polarization channels is greater than 20 d B.Therefore,the excellent electrical performance is certified.2.The spaceborne broadband reflectarray antenna technology is studied.Firstly,a single-layer reflectarray unit cell with a patch of three metal square rings nested is proposed,which effectively expands the bandwidth through the nesting design of square metal rings.The phase-shifting range of the unit cell is greater than 360° within the incident angle of 60°,and the reflection amplitude is less than 2d B within the incident range.On the basis,a bias-fed reflectarray is designed,and influence of multi factor in the engineering implementation of reflectarray is carried out as the tolerance analysis.The measured results of the reflectarray show that the aperture efficiency is greater than 44.5%,and the 3-d B gain bandwidth is 17%.With the results,the broadband design is basically realized.The reflectarray can realize ±52° beam-steering,and the gain loss is less than 3d B.It has the characteristics of large scanning angle.Secondly,an innovative glass based reflectarray antenna operating in V-band is proposed.It can be integrated with solar panels to improve the payload capacity with low loss and low cost.The unit design adopts the double-layer glass structure,which avoids the air cavity between the traditional unit dielectric plate and the ground,and realizes the double-layer combination through the metal bonding between the glasses.The unit cell is simulated and proved to gain a bandwidth of 19.6% and a good amplitude phase consistency curve within ± 40°.Through the simulated and prototype measured results of 0 ° and 30 ° static reflectarray,the aperture efficiency of the reflectarray reaches 46%,which is the first time on the V-band reflectarray antenna,and its 3-d B gain bandwidth reaches 19%,which has highly competitive electrical performance.3.The low-profile reflectarray and reconfigurable reflectarray antenna technologies are studied.Firstly,through the research on the near-field coupled feeding technology,a feed source based on the leaky wave structure is innovatively designed,and the irradiation efficiency of the feed source is improved by the side-feeding of two CTS structures.In addition,the design of the feed source adopts the waveguide magic T to provide in-phase and out-of-phase excitations for the two CTS structures,therefore,to obtain the simultaneous sum and difference beams to achieve antenna calibration or target tracking.The overall thickness of the reflectarray based on this feed is less than 3% of the traditional front-feed reflectarray with the same aperture,and will not increase with the expansion of the array scale,which can provide excellent low-profile characteristics.Secondly,in order to improve the efficiency of the reconfigurable reflectarray,a 2-bit reflectarray unit cell consisting of a polarization layer and a reflector layer is developed by using a hybrid configuration of tunable polarization and tunable resonant electrical length,which is configured to possess polarization rotation and 2-bit phase shift.Compared with the traditional 2-bit reflectarray unit cell,the proposed design utilizes the irrelevance between polarization and frequency,and effectively expands the bandwidth.Finally,based on the above-mentioned low-profile feed and 2-bit reflectarray unit,a novel reflectarray antenna with ultra-low profile and 2-bit phase quantization beam-steering capability is proposed.In order to verify the design concept and beam-scanning performance,a prototype with 9×67unit cells is designed,processed and measured.The experimental results show that the aperture efficiency is 35.1% and the irradiation efficiency is 43.4%,which can realize two-dimensional beam scanning in the range of ± 30°.The reflectarray is scalable and provides a feasible low-cost solution to develop low profile,high gain and beam scanning array antennas for satellite applications. |
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