Research On Key Technologies Of New Fusion Integrated Filtering Antennas

With the rapid development of wireless communication technology,especially the fifth generation(5G)mobile communication applications have opened the era of connection of everything and penetrated into various industries,which means that more and more active and passive components will be used in wireless communication systems.In view of the fact that the available space of the RF front-end is extremely limited,and the antenna and filter are two particularly important components,the collocation and coordination of the two will directly affect the communication efficiency and quality of service of the whole system.The traditional RF front-end layout not only fails to alleviate the pressure of the scarcity of space resources,but also the insertion loss caused by the filter and the transmission loss caused by the connection with the antenna will be unavoidable.This will also seriously limit the expansion of the communication system to a large-scale antenna array.In view of this situation,the integrated design product of filter and antenna,that is,filter antenna,has entered the field of vision of the majority of researchers and scholars in recent years because of its well in-band radiation performance and out-of-band suppression characteristics.Meanwhile,the further development and exploration of this topic will also become the main research content of this dissertation.The main contents of this dissertation are as follows:1.Based on the integrated design scheme of filtering antenna,the single-layer microstrip patch filtering antennas are studied.A total of three types of filtering antennas are designed.The first antenna mainly uses the splicing effect of the central open-circuit stub-loaded resonator and the surrounding parasitic patches to complete the design of filtering antenna.The length of the loaded symbiotic stubs and four parasitic slender microstrip lines will separately control the positions of resonant points radiation nulls at low and high frequency bands.Two transversely symmetrical short-circuit metal columns can shorten the distance between the new lower resonant point and the inherent resonant points corresponding to1/2-wavelength microstrip patch,and another pair of axisymmetric parasitic rectangular patches can enhance the suppression level along the right side passband by adding a radiation null.Finally,an elliptical bandpass response with three resonance points and three radiation nulls is obtained.The main radiation patch of the second antenna has a connected integrated structure,which can be regarded as a third-order stub-loaded resonator.The overall design is simple and compact,and its relative bandwidth of 28% and in-band gain of 5.3±0.2d Bi can be achieved with a profile limit of only 0.047λ.The main feature of the third antenna is that a row of short-circuit metal columns deviating from the central axis is used to excite and regulate the resonance point and radiation null at low frequency.The parasitic patches on both sides can not only regulate the resonance and filtering effect of high frequency,but also can be shared in an array,which has strong practicability.2.Based on the differential feed network,the dual-polarized Fabry-Perot(FP)resonator filtering antenna with wide stopband harmonic suppression is studied.Firstly,a side-fed dual-polarized antenna with a single resonant point is built by using the lower step-impedance feedline and an upper metal resonator.By reorganizing the parallel ring resonator and adding four half-wavelength L-shaped parasitic branches to the feed network,the transmission channel from the lower feed network to the upper resonator can be increased.The coupling effect between adjacent transmission channels can not only improve the impedance matching effect within passband,but also excite the radiation nulls near the passband.With the support of five radiation nulls,the antenna also exhibits a wide stopband suppression effect on both sides of the passband.Finally,the antenna has been processed and tested,verifying its feasibility of the scheme.3.The dual-polarized base station filtering antenna used in 2G/3G/4G LTE wireless communication system is studied.The two designed filtering antennas use ring coupler open-circuit stub loading technology and half-wavelength parasitic microstrip coupling technology,respectively.Among them,the open-stub microstrip line loaded by the first antenna helps to generate the resonance point and radiation zero at high frequency,and the joint action with the low frequency radiation null based on Barron feeder can make the antenna obtain bandpass filter response.The second antenna uses two groups of U-shaped half-wavelength parasitic microstrip lines to optimize the passband impedance matching effect and improve the out-of-band edge selectivity.These two antennas can not only cover the target frequency band,but also effectively suppress the adjacent frequency band.4.The dual-polarized base station filtering antenna used in 5G Sub-6G N78(3.3-4.2GHz)wireless communication system is studied.A total of two different types of filtering antennas are designed.The first antenna uses the equivalent source theory to develop the formula derivation and pattern analysis of ring-slot half-wave vibrator combination antenna,giving the model of combined antenna under differential excitation.The required bandpass response with wide stopband suppression is achieved by using the techniques of feeder open-circuit stub loading and slot internal stub loading.The second antenna uses the near-slot coupling technology to provide excitation signals to multi-layer structure,loading a short-circuit vertical slot on the cross-shaped slot arm and adding a parasitic radiation patch on the upper layer,which can improve the edge selectivity of the stopband on the antenna and the effect of out-of-band harmonic suppression.And then,etching the C-shaped groove in the floor layer can improve the polarization isolation within ±50° of the main radiation direction.Both of them can provide a feasible alternative for the future5 G communication system.