Research On Smart Skin Antenna And Miniaturized Antenna For Wireless Communications

As a multi-functional and intelligent antenna system,smart skin antennas are realized by introducing a perception layer as well as a control and execution layer in the structure of the conventional skin antennas.And they can achieve working-state detection and adaptive regulation.To improve the aerodynamic and stealth performance,smart skin antennas are usually embedded into the aircraft and other equipment platforms for structural integration.When subjected to aerodynamic,vibration and impact loads,the antenna array will inevitably generate structural deformation,which results in gain decrease,beam deviation and sidelobe degeneration.Thus,it is necessary to investigate the radiation characteristic of deformed antenna array and compensation method to improve the antenna performance.In smart skin antenna systems,the compact and low-profile antennas help to reduce the total volume and weight,and the requirements for integration of structure and function can be satisfied.In the civil wireless communication systems,the terminal equipments are getting increasingly miniaturized,integrated,lightweight and portable,which also demands for antennas with simple configuration and small dimension.Therefore,it is of great significance to research on the miniaturized multiband/wideband antennas.Based on the scientific project and hotspot in antenna research,the dissertation engages in the research on smart skin antenna and miniaturized antenna for wireless communications.The major contributions obtained are listed as below:1.The system scheme of the smart skin antenna is studied.Combining the traditional conformal load-bearing antennas with intelligent structures and adaptive control technology,a smart skin antenna receiving system using electronic compensation is proposed.The system mainly consists of a composite skin antenna,RF receiving channels and beam control/measurement and control units,which meets the functional requirements for loadbearing,electromagnetic waves reception,performance detection and regulation.2.The composite skin antenna is analyzed and designed.(1)An array antenna composed of a load-bearing framework and antenna elements is presented.The framework and antenna elements are realized by employing 3D printing and printed circuit technology,respectively.And this leads to cost reduction and flexibility enhancement.(2)A distributed sensor network made up of the Fiber Bragg Grating(FBG)strain sensors is constructed,and contact measurement can be obtained to detect the deformation of antenna array.This method is rapid and accurate,and has little effect on the antenna structure.iii)The structure parameters of composite skin antenna are optimized,and a prototype is fabricated by adopting the composite process.The design method is validated by experimental tests.3.The radiation patterns of antenna array with small deformation and the electronic compensation method are analyzed.(1)The pattern function of array antenna is derived according to the superposition theorem,and its expression in the global coordinate is obtained by coordinate rotating and translating.The radiation patterns of microstrip array antennas before and after the defomation are calculated and compared.(2)The phase compensation method is developed and applied in compensating for symmetric arch-shaped,asymmetric wedge-shaped and spherical deformation.Caculated results indicate that the compensated and undeformed patterns are in good agreement in the regions of main lobe and adjacent sidelobes.4.The RF receiving channels and beam control circuits are investigated and designed.(1)Based on active phased array technology,the general structure of RF receiving channels and beam control circuits is presented.The modular design method is used for easy maintenance and debugging.Besides,the circuit modules are extensible and reusable.(2)According to the main technical and functional requirements,the cascade RF channels are constructed which include the amplifier,variable attenuator,phase shifter and power combiner.Besides,the distributed beam control circuits are designed to realized the functions of beam/switch control,power management and external interfaces.(3)The hardware circuits are fabricated and tested,and it is demonstrated that the measured performance basically meets the design targets.5.The quasi-static compensation performance of the proposed smart skin antenna receiving system is tested and investigated.(1)An experimental equipment for generating deformation and a measurement and control software platform are both designed.The former mainly contains antenna clamps,sliding rail,stepper motors and etc.The latter is developed by using C#,which enables interacting with the hardware system as well as data storing and processing through a visual interactive interface.(2)Amplitude and phase calibration of the receiving channels are implemented with the planar near-field scanning.Moreover,the radiation patterns under several deformation conditions are measured on basis of the planar array.By comparing planar,deformed and compensated results,displacement measurement and pattern compensation methods are verified.6.Miniaturized multi-band/wideband antennas for wireless communications are ainvestigated and designed.Based on planar printed antennas,(1)an asymmetric coplanar strip(ACS)-fed multi-band antenna is proposed,which achieves nearly 50% size reduction compared with coplanar waveguide(CPW)-fed antennas.The multi-band characteristic is realized by etching two rectangular split-ring resonators(SRRs)on the radiating patch.(2)A multi-band antenna with a compact radiator is presented.The bended resonant branches are employed,and dipole-like radiation patterns can be produced.(3)Two types of miniaturized ultra-wideband(UWB)antennas are developed,and two multiple-input–multiple-output(MIMO)antennas are also proposed,each of which consists of two antenna elements with mirror or orthogonal arrangement.Besides,the isolation between elements is enhanced by adopting decoupling technology.