| Digital reconfigurable array antenna combines digital control circuitry with reflective array antennas by loading semiconductor devices.Without changing the external physical structure of the antenna,changing the circuit signal output by the digital control circuit can realize adaptive transformation of the main beam of the reflective array.The characteristics of beam scanning and beam agility make it very widely used in wireless communication and radar imaging.This thesis focuses on the digital reconfigurable reflective array antenna,studies the design and verification method of the reflective unit,and analyzes the working principle and performance characteristics of the far field radiation problem of the reflective array antenna.The main work of this thesis is as follows:The first chapter introduces the research background and significance of digital reconfigurable reflectors,and briefly describes the development history of reflector array antennas.According to the commonly used reconfigurable technology,the development status of the reconfigurable reflectarray antenna is introduced,which provides more guidance for the design of the digital reconfigurable array reflector antenna.The second chapter describes in detail the basic working theory of the microstrip reflectarray,the method of solving the compensation phase required by the reflector unit,and the common compensation phase implementation method.Then,a method of the digital phase quantitative analysis is put forward and explained.Finally,three common methods of reflectarray elements simulating are introduced.These contents lay a solid theoretical foundation for the design of reconfigurable reflectarray antennas.In chapter three,based on the working theory of the slot-coupled antennas,a 1-bit slot coupled reconfigurable reflectarray antenna is designed and proposed by loading the PIN diodes.Firstly,the working principle of the slot-coupled reflective unit is analyzed,and a relatively simple design idea is proposed based on the principle and the design method of the reflective unit.Then,a reconfigurable reflective unit is proposed by controlling the different states of the PIN diode with a phase difference of 180°.In addition,according to the design of the reflective unit,a 1-bit digital reconfigurable reflectarray antenna with a total of 100 reflective units is designed,that operating in the X-band.The simulated results show that the proposed antenna can achieve adaptive scanning of the main beam and the scanning angle can reach 50 degree.Finally,the application of the reconfigurable reflector array antenna in cleaning the blind area of the base station and the microwave aperture imaging is briefly described,which provides a practical idea for the reconfigurable array reflector antenna.The fourth chapter designs a planar microstrip 1-bit reconfigurable array antenna by loading a lower loss and cheaper PIN diode,which is based on the previous research.Firstly,combining with HFSS and ADS,a design method of reconfigurable reflective unit that can be quickly designed and can be accurately verified is proposed.And this method was used to design a 1-bit digital reconfigurable reflective unit operating at 4.75 GHz.Then,this reflective unit is used to perform a 12×12 array synthesis simulation and the overall array processing;At the same time,in order to simultaneously control 144 circuit signals,a hardware digital circuit control board was designed and processed.It can control the working status of the PIN diode on each reflective unit,and can check the circuit error through LED array to ensure the normal work of PIN.Simulated and measured results show that the antenna can achieve adaptive scanning of the main beam in two-dimensional directions at a frequency of 4.75 GHz.And the scanning angle can reach 50°.Experimental tests confirm the antenna's beam scanning capability.Finally,a 2-bit reconfigurable reflection unit working at 6.2 GHz was designed to lay the foundation for the design of multi-bit reflector arrays. |
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