Circular-polarization discrimination appears in many antennas＇ applications. A compensation approach based on multilayer film structure is proposed to improve the axial ratio of the magnitude of the two perpendicular modes of the lump ports. The goal is to widen the beamwidth of radiation that has an axial ratio less than 3 dB and thus reducing the complexity at the receiver. A transfer matrix method was developed to represent the multilayer film and characterize its performance. Simulation using high frequency structure simulator shows that a crossed dipole, as an example, can achieve a beamwidth of more than 30° at the frequency of 12.45 GHz after compensation. Finally, conclusions and future work about this compensation method are presented.
The properties of the linear chirped fiber grating （CFG） which is used in the true time delay unit of the optical beamforming networks （OBFNs） are studied intensively through theoretical analyses and numerical calculations. It is concluded that the dispersion of the CFG is equal to 1/（3Gc）, where G is the chirp coefficient of CFG and c is the light speed. Based on this relationship, a simplified designing process of a CFG which satisfies the requirements of the O13 FN is given. The simula- tion results are coincident with the theoretical conclusions.
针对目前IP over WDM网络中的路由算法在负载均衡方面存在的问题,提出了一种考虑负载均衡的新型联合路由算法——负载均衡算法(LBA).该算法在链路(包括逻辑链路和物理链路)权值分配过程中考虑了节点负载的影响,并且在目标函数的选取中充分考虑了链路资源的利用情况.通过对节点负载分布的方差和业务阻塞率的仿真分析,验证了该算法在负载均衡和网络资源优化利用及降低端到端时延等方面的优越性.
对波分复用(Wavelength Divisi on Multiplexing,WDM)网状网中的动态域间流量疏导问题进行了深入研究.在源路由模式下,提出了一种基于固定备选路由方式的动态域间流量疏导算法,并在其基础上提出了只考虑波长均衡和同时考虑波长均衡与业务均衡的改进方法.该算法可以有效地避免路由环,得到较低的阻塞率,节省全网的收发器数目和波长资源.仿真结果表明,这种算法可以有效地改善网络性能.
