Research On Multi-functional Antenna Based On Electromagnetic Complementarity Principle

With the development of self-driving,virtual reality and other emerging technologies and the promotion of 5G,the wireless communication scene is becoming more and more complex.In order to meet the fast and high-capacity communication in these scenarios,the communication system needs to have more excellent and diverse performance.The circuit part of the equipment already has a relatively mature integration technology,but as the first loop in the system,the antenna is difficult to integrate with other parts.Too much pursuit of the integration of antenna and circuit will greatly degrade the performance of the antenna to a certain extent.Therefore,in the case of improving the antenna integration as much as possible,how to achieve excellent performance and diverse functions of the antenna has always been a technical problem.Compared with other types of microstrip antennas,the antenna based on electromagnetic complementarity principle has a more flexible design method,and can achieve a variety of radiation performance suitable for different application scenarios,which improves the possibility of realizing a better multi-function planar antenna in the future high-frequency fully integrated system.At present,the research on electromagnetic complementary antenna is mainly based on the combination of separated structures.The volume of the antenna is usually large,and the radiation pattern is mainly focused on unidirectional radiation.Then other radiation types of electromagnetic complementary antennas or multi-function antennas guided by the principle of electromagnetic complementarity still have potential to be explored.In this thesis,according to the principle of electromagnetic complementarity and different application requirements,several kinds of planar antennas with different radiation properties are realized.The main work is as follows:1.A planar antenna with unidirectional radiation based on the principle of electromagnetic complementarity and a three-port MIMO antenna are proposed.A monopole branch in the same plane is introduced into a loop antenna equivalent to a magnetic dipole,and they as a whole,realize the characteristic of unidirectional radiation.In addition,this antenna is used as a unit to realize a three-port MIMO antenna.The innovation of this design lies in the ingenious use of the current distribution characteristics of different parts of a single planar structure rather than the three-dimensional combination of discrete structures,and the further realization of the MIMO antenna shows excellent pattern diversity performance and low correlation coupling.The design is suitable for multi-input and multi-output systems requiring low profile and high isolation.2.A quasi-isotropic planar antenna based on electromagnetic complementarity principle and another antenna to realize filtering response are proposed.A half-mode patch/half-mode SIW equivalent to a magnetic dipole acts as a fan-shaped monopole through lumped capacitance coupling excitation.They act together as a whole and a quasi-isotropic radiation can be obtained.Furthermore,a quasi-isotropic antenna with filtering response is realized by introducing a uniform impedance resonator.The innovation of this part is that the filter response is realized on the planar quasi-isotropic antenna for the first time,which helps to reduce its contribution to the noise figure when integrated with the circuit.This design has potential application value in future Internet of things systems that require omnidirectional coverage and filtering of irrelevant signals.3.A planar antenna with omni-directional circularly polarized radiation based on electromagnetic complementarity principle is proposed.Based on the dual principle,the antenna is flipped periodically at the zero point of the high-order mode of the half-mode microstrip antenna,thus an equivalent long magnetic current source array is generated at the opening.At the same time,a rectangular patch is introduced periodically at the junction of two adjacent elements on the upper and lower surface,and a transverse current is generated along the same direction to achieve an equivalent long current source array.The omnidirectional circularly polarized radiation can be realized by combining two parallel array sources with a 90° phase difference.The innovation of this design is that the standard omnidirectional radiation with high circular polarization gain and wide band coverage is realized on the planar structure for the first time,which makes it a preeminent candidate for integrated RFID/WLAN systems.