Research On Efficient And Multi-Functional Huygens Source Electrically Small Antennas

Antenna is an indispensable component in wireless communication system,and its miniaturization,anti-interference degree become an urgent demand for the development of antenna subsystem in wireless communication system.On the one hand,the miniaturization of the antenna unit is an effective way to improve the communication quality.In theory,the more antennas placed in a certain space resource,the stronger the anti-interference ability,so the miniaturization of the antenna unit is very important.On the other hand,the increasingly complex electromagnetic environment requires wireless communication systems to evolve towards intelligence.The multi-functional integrated design of the antenna unit can make a single antenna not only have multiple radiation characteristics but also replace the position of other devices in passive systems,namely the multi-functional and integrated design of the antenna is an effective way to realize the intelligentization of the compact antenna.Therefore,the miniaturization and multi-function of antenna design is the inevitable trend of antenna development in modern wireless communication.In this context,based on the comprehensive design method of Huygens source antenna in dissertation,the multi-band technology,dual polarization technology,filtering technology and reconfigurable technology were integrated into the antenna design to solve the electromagnetic wave operation mechanism and principle problems involved in the design process of multi-functional Huygens source electrically small antennas（ESAs）.Finally,the research on the key technology of the Huygens source antenna with miniaturization,anti-interference and intelligence was completed,and a series of high efficiency and multi-function Huygens source ESAs were developed.The research results will provide strong support for the construction of increasingly compact and intelligent mobile terminal systems and wireless communication platforms.The main innovation achievements are as follows:（1）Aiming at the problems of low radiation efficiency and poor directivity of dual-band electrically small antenna.A dual-band Huygens source ESA design method is proposed in this this dissertation,in this design,two pairs of magnetic and electric dipole near-field resonant parasitic（NFRP）elements are combined in a low-profile,electrically small package.The NFRP elements are excited effectively using only one specially designed feed structure.At the same time,additional parasitic rectangular strips or slots on the NFRP elements are introduced to mitigate the mutual coupling effects between the pairs of NFRP elements in different frequency bands,high efficiency,dual-band directional radiation is achieved in electrically small size.（2）Aiming at the problem of serious deterioration of isolation between two ports of dual polarization ESA.A novel design method of dual polarization Huygens source ESAs is proposed in this dissertation.The first is a dual-linear polarized design.By orthogonally combining two pairs of magnetic and electric dipole NFRP elements,and a compact and special feeding structure is introduced to excite the NFRP elements,which achieves good impedance matching and high port-to-port isolation（better than 25.8 d B）in the passband.The second one is a dual circularly polarized design.Without loading any decoupling structure,the antenna rotates and interleaves the left-hand circularly polarized NFRP element and the right-hand circularly polarized NFRP element to form a 45°rotation difference,thus resulting in high port-to-port isolation（better than 15.6d B）with good left-and right-hand circularly polarized Huygens source radiation characteristics.（3）Aiming at the problem of how to achieve directional,electrically small filtenna.The filter is effectively integrated into the Huygens source ESA in this dissertation,and two pairs of finger-based interdigital capacitor（FIDC）structures are integrated into the magnetic dipole NFRP element to generate two independently adjustable radiation nulls to form a band pass filtering characteristics,thus good out-of-band suppression level of the Huygens source ESA is achieved.Further,two Huygens source filtennas operating in different frequency bands are compactly arranged(0.12λ_Low)to propose a Huygens source ESA suitable for dual-frequency full-duplex system.The antenna utilizes the good out-of-band rejection characteristics of the Huygens source filtenna to achieve high isolation（better than 30 d B）between the lower and higher frequency antenna elements without any decoupling structure.（4）Aiming at the problem of how to achieve high performance reconfigurable ESA.An aperture multiplexing method for the fusion design of reconfigurable technology and Huygens source ESA is proposed in this dissertation.The first is the polarized reconfigurable Huygens source ESA.The antenna is loaded with an innovative reconfigurable driven element,which can change the current pathways on the driven element by controlling the ON/OFF state of six PIN diodes,and selectively excites the requisite NFRP elements to achieve the reconfiguration of four polarization states at the same frequency band.The second is the beam reconfigurable Huygens source ESA.A pair of PIN diodes is integrated into the antenna’s driven element.By switching the ON/OFF states of the diodes,the antenna can realize two independent unidirectional endfire radiating states whose peaks point in antipodal directions and a bidirectional endfire radiating state.The third is frequency-agile and beam-switchable Huygens source ESA,which integrates two varactor diodes on the magnetic and electric dipole NFRP elements,respectively.By changing the capacitance values of these two varactor diodes to change the phase relationship between the magnetic and electric dipole NFRP elements,the antenna realizes two independent,antipodal,unidirectional endfire radiating states with similar realized gain and front-to-back ratio values within virtually the same frequency-agile ranges.