| With the advent of the 5G/6G era,millimeter waves are bound to shine in the field of wireless communications due to their wide absolute bandwidth,good confidentiality,and high transmission quality.The patch antenna has the advantages of simple structure,ease of fabrication,ease of integration and low cost,so it is very suitable for the design of millimeter-wave antennas.However,the bandwidth of single-mode patch antennas is usually narrow,which can not meet the application requirements of broadband millimeter-wave mobile communication systems.Using two or more resonant modes of a single patch can effectively broaden the impedance bandwidth of the patch antenna.But for the resonant modes of single patch,the high-order modes between the TM10/01 and TM30/03 modes can not realize the broadside radiation directly,and the high-order modes above the TM30/03 mode are difficult to suppress the radiation of grating lobes.Therefore,in view of the problem that it is difficult to balance the wide impedance bandwidth and low side-lobe broadside radiation characteristics in the multi-mode single patch antenna,we propose a multi-mode multi-patch design theory and technology suitable for the design of millimeter wave broadband patch antennas.It includes three realization forms: conjoint patch-pair,mushroom array and segmented patch.In addition,this dissertation also proposes a millimeter wave dual-beam end-fire antenna that can be applied to 5G terminal equipments.The innovative works introduced in this dissertation can be summarized as follows:1.A method for the design of millimeter-wave broadband patch antennas based on the thirdand fifth-order resonance modes of the conjoint patch-pairs is proposed.To achieve great compression on the frequency spacing between the third and fifth modes of the square conjoint patch-pair,a novel frequency-ratio-compression technology based on the loading of inductive vias is presented.With resort to an equivalent transmission line model,the mechanism of the proposed frequency-ratio-compression technology is theoretically revealed.In order to verify the validity of this method,on basis of the third and fifth modes of the rhombic conjoint patch-pair,a 4×4 and an 8×8 rhombic patch antenna array are designed.As indicated by the measurement results,the-10 dB impedance bandwidths of these two arrays are 29%(34.5-46.2 GHz)and 31.8%(33.1-45.6 GHz),respectively.2.A broadband high-isolated dual-polarized patch antenna array incorporating two types of dual-mode conjoint patch-pairs is proposed.Firstly,a K/Ka-band broadband 4×4 patch antenna array is designed based on the higher-order fifth and seventh modes of the conjoint patch-pair.Compared with the conjoint patch-pair working under the third and fifth modes,since the initial frequency between the seventh and fifth modes is lower,dual-mode characteristics can be achieved under a lower profile height.Secondly,by incorporating a pair of conjoint patch-pairs working under the third and fifth modes with a pair of conjoint patch-pairs operating under the fifth and seventh modes,not only the 0°and 90° polarizations but also high isolation and wide impedance bandwidth can be achieved.3.Two structure-reused shared-aperture patch antenna arrays are proposed.First,by inserting a pair of millimeter-wave conjoint patch-pairs into a pair of microwave conjoint patch-pairs,the dual-band microwave/millimeter-wave characteristics with large frequency ratio are realized.Using the hybrid feed structure of microstrip and slotline,not only the reuse of input feedline but also the routing of millimeter-wave signals are realized.Second,in order to achieve broadband coverage for K/Ka and Q bands,a dual-wideband radiator-reused shared-aperture patch antenna array fed by high-isolated crossed SIW and SICL is proposed.Taking advantage of the combination of substrate integrated waveguide(SIW)and substrate integrated coaxial line(SICL),a novel crossed feed structure with high isolation is implemented.By incorporating two types of conjoint patch-pairs,broadband characteristic is acquired in both the K/Ka and the Q bands.Because the radiator is completely shared,the aperture reuse rate reaches 100%.4.A method for the design of millimeter-wave multimode broadband patch antennas based on two-unit and four-unit mushroom arrays is proposed.Since the electrical size of each mushroom cell has reached 0.25?0×0.24?0(?0 being the free space wavelength at 40GHz),a much higher fabrication tolerance is obtained,in comparison with the traditional mushroom unit with a small electrical size.Utilizing the TM01 mode contributed by the two-unit mushroom array and the additional resonance mode introduced by the left and right substrate integrated apertures,the dual-mode broadband characteristic is realized.By expanding the scale of the mushroom array from 1×2 to 2×2,a new TM21 mode can be introduced on the basis of the original two resonance modes.By breaking the left-right symmetry of the mushroom unit,the radiation performance of the TM21 mode is greatly improved.Therefore,the broadband patch antenna composed of four asymmetric mushroom units can not only obtain the triple-mode characteristic but also stable broadside radiation performances.5.A broadband linearly-polarized and a broadband circularly-polarized segmented patch antenna are proposed.Through taking advantage of the TM01 and the deformed antiphase TM02 modes,the dual-mode broadband characteristic with independently controllable high-order mode is acquired.Since the deformed antiphase TM02 mode can provide two orthogonal current components with equal amplitude,this mode is further used to design circularly polarized patch antenna.In order to satisfy the phase condition of 3-dB axial ratio,a controlling technology for 90° phase difference based on the loading of L-shaped stubs is proposed.In order to eliminate the influence of stub loading on the amplitude ratio,a controlling technology for amplitude ratio based on corner truncating is proposed.The proposed linearly-polarized segmented patch antenna array can simultaneously cover the 5G frequency band presented by China,the United States,Europe,Japan and South Korea in Q-band,while the overlapping bandwidth for the 3-dB axial ratio and-10 dB impedance of the proposed circularly-polarized segmented patch antenna array can meet the requirements of the PAN in the Q-LINKPAN standard.6.A millimeter-wave dual-beam end-fire antenna is proposed.The integration of the two-element half-wave dipole array and the SIW 90° coupler contributes to the realization of switchable 0° and 180° directional beams.By loading two sets of zero-index metamaterial(ZIM)units,the gain enhancement of 0.7?1.2 dBi is obtained within the operating band... |
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