Research On Beam-scanning Leaky-wave Antenna At Fixed Frequency Based On Metamaterial

With the development of science and technology,modern communication systems are developing toward high integration and high reliability.In modern communication systems,antenna works as a key component for receiving and transmitting electromagnetic waves.Therefore,its design and innovation are crucial for the communication system.Beam-scanning antenna combines the advantages of omnidirectional antennas and directional antennas.It not only has a high gain,but also the direction of its radiation beam can be controlled mannually to meet people's different needs for communication.Leaky-wave antenna is widely concerned in the microwave field because of its own beam-scanning characteristics,and it has the advantages of low cost,easy manufacturing,high gain,low profile,narrow beam width,wide bandwidth at the same time.The left-handed materials developed in the past two decades have brought new opportunities for the development of leaky-wave antenna.Combining leaky-wave antenna with left-handed materials can achieve the radiation effect of beam-scanning at fixed frequency.The advantage of this fixed frequency beam scanning antenna is that it only requires ordinary electronic elements,and uses a very simple and compact feeding structure without any phase shifter to achieve beam scanning,which makes it an attractive low-cost alternative to realize beam-scanning performance.In summary,beam-scanning leaky-wave antenna at fixed frequency based on metamaterials has important theoretical significance and practical application value.The main work and innovations of this work include the following three parts:(1)A novel design of composite right/left handed beam-scanning leaky-wave antenna at fixed frequency based on basic transmission line is proposed.In addition to the basic radiation structure,the antenna also has corresponding electrically controllable feeding network and port matching structure.Finally,the antenna can be controlled by controlling the voltage of the varactor diodes to achieve beam scanning from-55 ° to +41° at 5.2GHz,and the overall angle coverage reaches 96 °,The maximum gain of the antenna is 4.46 d Bi,while antenna gain is 4.05 d Bi in the broadside direction.(2)A novel design of composite right/left handed beam-scanning leaky-wave antenna at fixed frequency based on substrate integrated waveguide is proposed.Since the basic guided wave structure of the antenna is substrate integrated waveguide,the antenna has the advantages of high gain,high radiation efficiency,and easy integration with other planar circuits.By introducing left-handed structure on the waveguide,the antenna can achieve a fixed-frequency beam scanning from-28 ° to + 22 ° at 16 GHz by controlling varactor diodes,with antenna gain higher than 10 d Bi.(3)A novel design of composite right/left handed beam-scanning leaky-wave antenna at fixed frequency based on corrugated substrate integrated waveguide is proposed.In order to overcome the defect that the upper and lower metal layers of the substrate integrated waveguide structure cannot be separated by voltage,the antenna uses the structure of corrugated substrate integrated waveguide.Since corrugated substrate integrated waveguide uses a quarter-wavelength microstrip line to replace the metal via of the substrate integrated waveguide,the loading of active devices becomes easier and feasible.By introducing left-handed structure on the waveguide,the antenna can finally achieve a fixed-frequency beam scanning from-50 ° to + 65 ° at 2.98 GHz through controlling the voltage of varactor diodes,with a total angle coverage of 115 °,and gain of antenna higher than 6d Bi.