Study On Planar Antenna Based On Resonant Loading

Antenna is an important part of radio information system.With the rapid development of wireless communication and information technology,it is required to be miniaturized,multifrequency and wideband.At present,the continuous advancement of printed circuit technology has promoted the development of antenna design.Printed antennas have received extensive attention and research due to their low profile,small size,flexible design,and easy integration.For example,the microstrip patch antenna has good directivity and is covenient to form an array antenna to obtain high gain;the printed monopole antenna is omnidirectional and easy to achieve multi-frequency characteristics.Therefore,these printed antennas are widely used in satellite communication,radar,mobile communication and other communication equipment.In recent years,antenna based on the principle of closely spaced loading technology has become one of the research hotspots because of its unique advantages,such as no additional impedance matching network and high radiation efficiency.In view of the application of closely spaced near-field loading technology in antenna miniaturization and multi-frequency bands,the thesis takes miniaturized microstrip patch antennas and multi-functional printed monopole antennas as the research objects,and studies a series of closely spaced near-field loading planar antennas.The main research results of the thesis include:(1)The design idea of planar antenna loaded with near-field closely spaced resonant element is summarized.The loading technology and the principle of closely spaced loading are studied,and the application of loading technology in antenna miniaturization and multifrequency is introduced in detail.The structure of various reactance loading elements and the coupling relationship between them and the driving element are sorted out in order to simplify and clarify the circuit structure and component relationship,and reduce the analysis complexity of antenna system based on resonator loading as far as possible.The design idea of planar antenna loaded with near-field closely spaced resonant element is summarized.(2)It is proposed that the ?/4 transmission line resonator can be used as a reactance element,embedded in the near field of the microstrip patch,and the resonance frequency is reduced by coupling the edge of the radiating patch with the ?/4 transmission line resonator.The ?/4 transmission line resonator was embedded in the radiation patch of the microstrip patch antenna,and the resonator was used as a reactance loading to couple with the edge of the radiation patch to reduce the resonant frequency of the antenna.At the same time,because the resonator is embedded in the microstrip patch antenna,the overall size of the antenna is not enlarged,and a compact microstrip patch antenna is realized.Based on the equivalent circuit,the antenna was simulated and analyzed.(3)It is proposed that resonators with different structures can be used as closely spaced nearfield reactance loading elements,and it is clearly pointed out that single-sided conductor planar resonators can be used in the field of antenna design,and the structure of reactance loading elements has been expanded.Four printed monopole antennas based on resonator loading are designed.The resonator is loaded near the antenna as reactance element,and its equivalent circuit is analyzed and parameters are extracted.Three coupling modes between reactance loading element and driving printed monopole are introduced in detail.The corresponding equivalent circuit models of the three coupling modes are established,and the relevant performance parameters of the antenna are analyzed in detail.The differences and commonness of these four printed monopole antennas based on resonator loading are summarized.(4)It is proposed to use single-sided conductor planar resonators with different sizes(same structure)to couple with a driving printed monopole to achieve impedance matching of dualfrequency antennas.Several dual-band printed monopole antennas are studied.Based on the equivalent circuit model,the process of dual-band point matching is described in detail by using Smith impedance circle,and the radiation mechanism is analyzed.At the same time,two miniaturized dual-band printed monopole antennas are designed.At first,the drive monopole is miniaturized by meander technology.At the same time,different reactance loading elements are loaded in the near field of the drive monopole to realize dual-band characteristics.By analyzing the surface current distribution of these miniaturized dual-band printed monopole antennas,the radiation characteristics of the antennas are summarized and verified by simulation.The above work focuses on the study of planar antennas loaded by resonators.These methods of loading resonators at close range are not limited to these specific planar antennas,and can also be extended to antennas with other structures.