Research On Duplexing Filtering Antenna Arrays Based On Multimode Resonators

With the development of wireless communication system,compact structure,light weight and multifunction have become the new trend of RF front-end.Traditionally,antennas and filters are designed separately.The transmitting and receiving signals are accomplished by antennas,while the filters are responsible for selecting signal.Filters are usually composed of resonators which have the same resonant frequency as the antenna.The antenna cascades the filter through 50? transmission line and matching network.Because the bandwidth of the antenna is different from the filter's,they may not match at the edge of working band,which lead to increase the return loss and the performance deterioration.Duplex filtering antenna takes the antenna as the last-order resonator of the filter,which can realize antenna with filtering characteristic,enhancing bandwidth and improving frequency selectivity.The interference caused by harmonics is another issue in wireless communication systems.The corresponding filter network can be designed to suppress harmonics.In order to improve antenna gain,antenna arrays can be designed.Antenna arrays need appropriate feeding network to excite each radiation element with specified amplitude and phase.Traditional antenna arrays usually introduce quarter-wavelength transmission lines and stubs for impedance matching,which makes the feeding network very huge and complex.The introduction of filtering power divide network can avoid the complex matching network.Therefore,this paper focus on the duplex filtering antenna,the duplex antenna with harmonic suppression and the high integration duplex filtering antenna array and the following three antenna designs are completed:1.A duplex filtering antenna with harmonic suppression on T-shaped resonator is proposed.The stack patches in transmitting channel and receiving channel are fed by two T-shaped resonators respectively.Using the transmission zeros generated by a quarter-wavelength short-circuit line at high mode frequencies,the even-time harmonics of the antenna are suppressed.Because the whole antenna is fed by coupling,the energy can only be transferred to the patch at the frequencies where both T-shaped resonator modes and antenna modes are resonant,which improves the out-band suppression.Compared with the traditional patch antenna,the antenna achieves wider bandwidth,more stable bandwidth gain and better harmonic suppression performance.2.A duplex filtering antenna array with harmonic suppression on T-shaped resonator is proposed.Hairpin resonators are used to excite microstrip patches via slot on the ground to achieve dual-frequency co-polarization radiation characteristics.The two T-shaped resonators are used as filter circuits and power distribution networks of antenna arrays.Thus,the integration of the antenna array is improved and the volume of the antenna array is reduced.In addition,the antenna array achieves the characteristics of harmonic suppression.3.A duplex filtering antenna array on SLR is proposed.The dual-frequency radiation element is composed of the microstrip patch and the hairpin resonator.SLRs are used to realize the filtering network and the power distribution,which improves the integration of antenna array and reduces the volume of antenna array.The antenna array achieves good frequency selectivity,improves gain flatness,and improves bandwidth and port isolation.