Study On Mobile Base Station Antennas And Shaped-beam Antennas

Antenna is one of the key components of mobile communication systems. With the fast development of mobile communication system, the system is more and more complex, which demands the character of antennas with higher quality. The base station antennas in mobile communication system have two key types:out door base station antennas and indoor base station antennas. Firstly, the base station antenna element is analyzed and designed in this dissertation; A hybrid genetic algorithm formed by integrating a hill climbing method into the genetic algorithm is proposed, which is utilized to produce shaped-beam of the mobile communication base station;Three ornamental and disguised antennas for indoor base station applications are proposed; Secondly, widebeam circularly polarized antennas for Beidou satellite communications are investigated; Finallly,a second exploiture CAD of HFSS software is presented to analyse the edge slot waveguide arrays and two edge slot waveguide arrays for radar applications are designed by using the second exploiture CAD software. The author's major contributions are as follows:1. Two novel dual polarized wideband antenna elements with high isolation are designed for base station applications.The first wideband dual polarized antenna element consists of four end to end folded dipoles and a U-shaped ground.The second antenna element comprise four circular folded dipoles,a U-shaped ground and coupling folded dipoles. The two antenna elements above have the characters of broad bandand, high isolation,compact structure, and are already used widely in base station antennas.2. A novel synthesis of base station array with shaped-beam pattern is presented. Firstly, a hybrid genetic algorithm formed by integrating a hill climbing method into the genetic algorithm is proposed, which presents the optimization higher efficiency. Secondly, the proposed synthesis has taken the actual element patterns into account, which can reduce the error made by the neglect of the mutual coupling and improve the accuracy of the calculation. The optimization method is utilized to design an applied upward side lobe suppression and downward null filling of the base station array. The broadcast beam and work beam of TD-SCDMA smart antenna array are designed using this method, too.3. Three broadband and multiband antennas are designed for indoor base station applications. The first one comprise inverted cone and spherical segment. Owing to its low profile and wide impedance bandwidth, this antenna is suited for indoor wireless base station antennas mounted on the ceiling. A method for enhencing bandwidth of the second antenna through the combination of a 3D transition fed circular patch with parasitic elements is proposed. The second antenna has wideband dual-frquency characteristics and has a beam tilted downward with a broadside beam pattern on the horizontal plane. Consequently, this antenna should find applications in the modern multi-band indoor wireless communication systems. The third one is a triple-band planar monopole antenna with novel tri-sleeves structure developed for multiband wireless communication. The dimensions of the proposed antenna is only 150 x 140 x2 mm3. It can be hidden almost anywhere within a structure while still providing full sized RF performance.4. A multi-band dual circulaly polarized combined three-in-one antenna is designed by using technologies such as high substrate, dielectric surface wanve microstrip antenna,optimization of ground structure and tilted downward cross dipoles.The measured results of the composition antenna indicate that the low elevation gain meets the demand of Beidou communication systems.5. A high performance receiving antenna with high rejection of the cross polarized, hemisphere coverage,widebeam and very sharp slope shaped pattern is designed through optimization method and NEC software.The antenna is suited for future automatic navigation and landing systems application.6. A low side lobe edge slot waveguide LFMCW radar array antenna at azimuth plane is presented through a second exploiture CAD of HFSS software. Meanwhile,by putting the edge slot waveguide into a horn, the vertical plane beamwidth of the array antenna is reduced, the gain and the receiving to transmitting isolation are enhanced too.7. A large plane edge slot waveguide arrray antenna is poroposed by using the second exploiture CAD of HFSS software and a hybrid genetic and hill climbing algorithm. The array antenna has a side lobe patten at azimuth plane and square cosecant pattern at vertical plane.