Microstrip Filter Antenna Design And Application Research

With the rapid development of wireless communication technology,the RF system with miniaturization,integration and multi-function is becoming the focus of discussion.As the integration of antenna and filter,the filtering antenna can not only reduce the size of the whole system,but also improve the overall selectivity and the level of out-band suppression with good radiation characteristics.In this paper,two main design methods of the filtering antenna are researched and two microstrip filtering antennas with desirable performance are designed.The main contents of the paper are as follows:Firstly,the current research status of the filtering antenna is expounded,and the two main design methods of the filtering antenna are analyzed and discussed respectively.Meanwhile,utilizing the even-odd mode analysis method,the E-shaped resonator is analysed and an instance is designed for the later chapters.Secondly,a compact wideband planar filtering quasi-Yagi antenna is presented.A compact feeding structure makes a contribution to the broadband and miniaturization of the planar quasi-Yagi antenna.For the implementation of filtering response,a E-shaped resonator is introduced by the parallel coupling structure.Results indicate that the proposed filtering antenna owns broad bandwidth and high selectivity with stale gain in the passband.In addition,the suppression on harmonics is more than the second harmonic.Thirdly,a dual-band orthogonal polarization microstrip filtering antenna array at C-band is designed.An E-shaped resonator is used to feed the microstrip patch by the slot on the ground for achieving a wideband antenna unit with high selectivity.Changing the size of the patch and the orientation of the coupling slot,two different antenna units are achieved with different center frequencies and orthogonal polarization.Then,a microstrip line is used for coupled feeding,and the antenna units with different frequencies are placed on the different sides of the feeding microstrip line at different distances.For each working frequency,microstrip line is resonant and the antenna units near the point with maximum current density are fed with the same phase for enhanced radiation.For other frequencies,the feeding phase of antenna units gradually becomes different,so the radiation is weakened.This feed structure can achieve good filtering characteristic.The dual-band orthogonal polarization microstrip filtering antenna array can achieve wide bandwidth,good radiation performance and low frequency ratio(1.11)at the same time,and it has high selectivity and isolation.The two microstrip filtering antennas designed in this paper can achieve wide bandwidth and have stable radiation in the passband.Meanwhile,these two antennas have good filtering response with compact structure,and own important value in some engineering applications.