| With the development of communication technology,the crowded frequency band at present has greatly restricted the efficiency of data transmission,while 5G millimeter wave frequency band has abundant spectrum resources,which undoubtedly occupies an advantageous position in the development of future communication.However,there are many problems in millimeter wave frequency band,such as large spatial loss and co-channel interference.Therefore,the design of millimeter wave antennas needs to consider indicators such as broadband,high gain,directivity,and multi-beam.Circularly polarized antennas have stable anti-interference ability,which can effectively increase the gain by forming an antenna array to be used in the field of millimeter-wave communications;Lumber lens can effectively improve the gain and directivity of the antenna,and can be applied to the long-distance Communication of millimeter wave;The beam scanning antenna can effectively alleviate the problems of multipath fading and co-channel interference in the millimeter-wave frequency band,and it also plays an important role in the design of millimeter-wave antenna.Based on theoretical analysis,this paper mainly studies broadband circularly polarized millimeter-wave array antennas,millimeter-wave Luneburg lenses,and millimeter-wave leaky-wave antennas.The research results can be briefly summarized as follows:(1)A broadband circularly polarized millimeter wave array antenna is designed.The unit radiation structure of the antenna adopts the form of "S"-shaped microstrip patch,and the slot-coupled feeding is used to broaden the bandwidth of the antenna.Due to the influence of the patch shape,the surface of the radiating element is excited to form a circular current.The circularly polarized patch antenna unit is formed into a 4×4 antenna array by adding a one-to-sixteen feed network to further improve the gain of the antenna.Finally,the antenna is processed and measured,and the impedance bandwidth of the antenna prototype obtained is 27.2GHz to 37.2GHz,the 3dB axial ratio bandwidth is 28.4GHz to 36 GHz,and the radiation gain is between 11.33 dBi and 17.81 dBi.(2)A wideband high-gain millimeter wave Luneburg lens is designed.First,the Luneburg lens was discretized and decomposed into a 4-layer structure.The dielectric constant of each layer structure was designed using effective medium theory.After the design was completed,the physical prototype was processed using 3D printing technology.In the actual test process,the feed antenna uses a Ka-band standard gain horn feed.After adding a lens,the gain of the antenna is increased by 9.92 dB ? 11.75 dB,and the 3dB wave half-width converges from 59°to 9°.(3)Two kinds of millimeter wave periodic leaky wave antennas are designed.Both of these two leaky wave antennas use the substrate integrated waveguide as the transmission structure.According to the working principle of the periodic leaky wave antenna,different perturbation structures are introduced to realize frequency-controlled beam scanning.The first antenna adopts the perturbation method of the metal layer slit.The impedance bandwidth of the optimized antenna is 26 GHz ? 36 GHz,the scanning angle is 2° ? 54°,and the peak gain can reach 13.64 dBi,but the radiation efficiency and gain stability Inferior;the second antenna adopts the perturbation method of opening holes on the side and introducing parasitic patches.The simulated and optimized antenna has an impedance bandwidth of27 GHz ? 36 GHz,a scanning angle of 4° ? 52°,and a peak gain of 11.93 dBi.At the same time,it has higher radiation efficiency. |
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