| With the rapid development of communication technology and the increasing demand of wireless communication,the multi-beam antenna are widely used in the fields.The multi-beam antenna is a passive network.Each of the input ports corresponds to a beam with a certain direction,which can be used for receiving and transmitting electromagnetic wave.At the same time,the multi-beam is orthogonal,which is used to improve the performance of the receiver by the spatial diversity reception technology.The traditional multi-beam network is N×N structure,for example,the typical 4×4 Butler network.The power of each output is equal.While the output feed an array antenna,the sidelobe level is equal to-12 dB.The way to optimize the side lobe is to increase the number of array units or to change the amplitude distribution.Therefore,it is very important to design a multi-beam network with N×M(M > N)for the research and engineering realization.The main component of the multi-beam antenna is a phase shifter,which is generally realized by the Butler matrix.It is a multi-port microwave network,it’s main function is to output the signals of certain amplitude and phase distribution to feed the antenna array in order to formed the beam of different directions.Therefore,the research on the miniaturization,broadband,lower loss of the Butler matrix has become the focus in recent years.In this paper,we mainly analysed the traditional 4×4 Butler matrix,and then designed a3×5 Butler network to meet the requirements of the three beam antenna with low side lobe.Firstly,the paper introduce the principle of the multi-beam antenna and Butler matrix.Secondly,a 4×4 Butler matrix with a center frequency of 1.95 GHz is designed.Again,a 3×5Butler matrix is designed to meet the output amplitude of the Chebyshev distribution,and the phase between output is constant.The test data are compared with the simulation results show that the 3×5 Butler network can satisfy the low side lobe demand of the three-beam antenna and reduced the overall size.Finally,the paper summarized the full text and put forward to the research direction. |
