Research On The Filtering Butler Matrices

With the rapid development of wireless communication technology,the multi-beam antenna communication system with beam pointing dynamically controlled has attracted great attention.Meanwhile,the requirements on device performance in the communication system have been constantly improved.In order to further reduce the size,the design of integrating multiple independent devices has attracted much attention in recent years.The Butler matrix and filters are the key components to realize the multi-beam antenna system.If they can be integrated,the size of RF front end can be reduced effectively.Therefore,some research about Butler matrix with filtering characteristic are carried out in this paper.The main contribution of this paper can be summarized as follows.(?)Based on the fact that the couplers are the most important component of the Butler matrix,a novel design method of 180° coupler with filtering characteristic based on all-resonator structures was proposed.Then the coupler was applied into the design of the filtering Butler matrix,and the design of a filter and the Butler matrix was integrated.At last,the design methods of 2×4 and 4×6 filtering Butler matrices based on all-resonator structures were proposed.(?)On the basis of the filtering Butler matrix,the non-uniform power output characteristic was further introduced into the design of the Butler matrix innovatively.The design of 4×6 and 2×8 filtering Butler matrices with non-uniform power output based on all-resonator structures are successfully realized by replacing couplers which are cascaded with the output ports of the Butler matrix with new non-uniform power output couplers and cascading non-uniform power dividers at each output ports of the Butler matrix.The realized Butler matrix can provide functions of filtering,power distribution and phase control.(?)In order to solve the problem that when 180° filtering couplers were used to design the Butler matrix,it is difficult to realize the phase shifters as the connected network are connected by couplings between the resonators.A novel design method for the filtering Butler matrix was proposed by the mixed use of the 180° filtering coupler and normal 90° coupler.Therefore,two 4 × 4 and 4 × 4 filtering Butler matrices based on part-resonator structures were designed successfully.(?)Based on the design schematic diagram of 8×8 Butler matrix,the design of 8×8 Butler matrix is creatively divided into two parts,which greatly simplified the design process of 8×8 Butler matrix.A design method for 8×8 Butler matrix with filtering characteristic based on part-resonator structures was proposed,and an 8×8 filtering Butler matrix was realized.