The authors present the modelling and design procedure for a finite dual-polarised notch phased-array antenna which has a triangular lattice to obtain a widescan ability in the azimuth and elevation planes. The array antenna has orthogonal linear polarisations for transmitting and receiving, and the triangular element grid is achieved by 45deg rotation of a square grid of notch elements in egg-crate configuration. A numerical waveguide simulator for the H-plane scan is modelled to eliminate scan blindness in the H-plane. A numerical model for the finite dual-polarised notch array is built to investigate the convergence of the active-element pattern (AEP) and the effects of the grating lobe according to array size. To verify the numerical results, a wideband active phased-array system was fabricated which consists of a 10times12times2 notch array, 8times8 transmit/receive modules and beam-forming networks. The scan patterns measured by near-field measurement show good agreement with the converged AEP for the finite array model and have widescan performance in the azimuth and elevation planes

A hybrid wireless network is an extension to an infrastructure network, where a mobile host may connect to an access point (AP) using multihop wireless routes via other mobile hosts. The APs are configured to operate on one of multiple available channels. Mobile hosts and wireless routers can select their operating channels dynamically through channel switching. In this environment, we propose a routing protocol that finds routes to balance load among channels while maintaining connectivity. The protocol works with nodes equipped with a single network interface, which distinguishes our work with other multichannel routing protocols that require multiple interfaces per node. The protocol discovers multiple routes to multiple APs, possibly operating on different channels. Based on traffic load information, each node selects the "best" route to an AP and synchronizes its channel with the AP. With this behavior, the channel load is balanced, removing hot spots and improving channel utilization. The protocol assures that every node has at least one route to an AP, where all intermediate nodes are operating on the same channel. Our simulation results show that the proposed protocol successfully adapts to changing traffic conditions and improves performance over a single-channel protocol and a multichannel protocol with no load balancing

In this work, we present numerical results which support SO(5) symmetry as a concept unifying superconductivity and antiferromagnetism in high-temperature superconductors. Using exact cluster diagonalization we verify that the low-energy states of the t-J model. A widely used microscopic model for high T c cuprates form SO(5) symmetry multiplets. Our results show that the d-wave superconducting ground states away from half-filling are obtained from the higher spin states at half-filling through SO(5) rotations. The dominant input-energy resonance in the dynamic spin correlation function corresponds to a ldquopi-resonancerdquo in the entire low doping region. The SO(5) symmetry is robust against the inclusion of longer range Coulomb repulsion and next-nearest neighbor hopping