| Millimeter-wave broadband high-gain antennas have important application value in military and civilian fields.In this thesis,for the application of key technologies in wireless communication systems,the theoretical research and design of high-order cavity-fed antennas are carried out,and good performance is achieved.The excellent performance based on the high-order-mode antenna is obtained.The research results can be widely used in antenna design for applications such as satellite-to-ground communication,Internet of Everything,and millimeter-wave/terahertz communication.The main novelties of this dissertation are as follows:1.In view of the mode distribution of the double-fed high-order-mode cavity,the theoretical calculation method of the modes in the double-fed cavity is proposed,and the correctness of the calculation results is verified by simulation.In-depth analysis of TE340,TE120 and TE130 and other modes were carried out,the slotting methods of different modes were discussed and the influence of different feeding structures was analyzed.We put forward two evaluation indexes:the ratio of maximum in a period and maximum position to judge whether the field distribution is suitable for circularly polarized radiation and the specific polarization that may be realized,and point out that using this double-fed highorder-mode cavity,any polarized radiation can be realized,which can be used to construct polarization-agile antennas.2.For the design of millimeter-wave multi-polarization antennas and the problems of low radiation efficiency in dual-linear polarization and dual-circular polarization antenna arrays,8×8 high-order-mode high-efficiency dual-linear and dual-circular polarization antenna arrays are proposed.Through the aforementioned theoretical analysis,A sequentially rotated patch radiation structure is proposed.Using four ±45° linear polarizations through sequential rotation,they are combined to form vertical linear polarization,horizontal linear polarization,-45° linear polarization,45° Linear polarization,left-hand circular polarization,and right-hand circular polarization.A dual-layer orthogonal feed network structure with shared vias is proposed to realize large dual-polarized antenna arrays.A dual linearly polarized 8×8 antenna array is proposed.TE340xand TE340y are excited in the cavity.The measured overlapping impedance matching bandwidth of the two-port is 11.6%.The port isolation is greater than 44.5 dB,and the measured gains of the two-port are 26.4 dBi and 26.2 dBi,respectively.A dual circularly polarized 8×8 antenna array is proposed.TE340x and TE340y with different phase differences are formed in the cavity.The impedance matching bandwidths of the two ports are 14.2%and 13.3%,respectively.The axial ratio overlap bandwidth is 10.5%.The measured maximum gain is 25 dBic.It has the highest gain and aperture efficiency among the published antennas of the same type and is a potential candidate for millimeterwave,satellite communication,and other related applications.3.To solve the problem that it is difficult to increase the gain and bandwidth of millimeter-wave antennas at the same time,we propose a 4 × 4 hybrid high-order-mode high-gain broadband antenna array,which realizes the simultaneous improvement of gain and bandwidth.A high-order-mode fed cavity structure with hybrid modes of TE340 and TE140 is proposed.By shrinking the size of the feeding cavity,the dielectric loss of the feeding network is reduced,and high gain is realized.Besides,the mode bandwidth is expanded at the same time,so that a stable radiation pattern within a broadband range is realized.An open-ended waveguide is adopted in the radiation structure to form four in-phase TE11 modes and widen the impedance matching bandwidth.The measured impedance bandwidth is 28.1%,covering 32.85-43.6 GHz.The aperture efficiency of the antenna is 94.7%,with a measured peak gain of 21.7 dBi.The simulation results are in good agreement with the measured results.effectively solving the problem of the narrow bandwidth of high-order-mode high-gain antennas.Among the published antennas of the same type,the gain is the highest,and the impedance matching bandwidth is the widest under the condition of the high gain.4.Aiming at the problem that the high-order-mode high-gain broadband antennas have a high profile,limiting their applications.We propose a highorder-mode embedded probe-fed low-profile antenna.An embedded probefed low-profile high-order-mode antenna is proposed to remove the coupling feed structure.Compared with the previous structure,the profile is reduced by 1/3 and the desired mode distribution in the cavity is suppressed.The etched metasurface on the top surface of the high-order-mode cavity is used to radiate,reducing the profile by 1/3,compared with the previous structure.By the metasurface loading structure,the antenna proposed in this thesis excites TE810 in the cavity of 0.84λ0 ×0.84λ0.So that a wider mode bandwidth of 34.3%is realized.The measured impedance bandwidth of the antenna is 35.8%,and the measured maximum gain is 12 dBi.The profile is 0.045λ0.The simulated results are in good agreement with the measured results,effectively solving the problem of high profile in the high-order-mode high-gain broadband antenna.Among the published antennas of the same type,the profile of this work is the lowest while maintaining high gain and broadband. |
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