A New Compact Coplanar Waveguide Stop Band Filter Based on Circular Shaped DGS for Microwave and Millimeters Wave Applications

This chapter introduces an overview of coplanar technology and the general techniques and process to improve the response and characteristics of microwave components. A new circular defected ground structure (DGS) with shaped coplanar line is investigated for compact stopband filter (SBF) for microwave and millimeter wave applications. With this structure, the response of resonant element in 20 GHz exhibits the bandstop function. The proposed DGS is also modified by introducing four symmetrical slots with L-configuration in conductor line of a coplanar circuit to improve separately the stopband and passband performances. An equivalent circuit model derived for the proposed structures will be provided.

Wake-induced oscillation behaviour of twin bundle conductor transmission lines

A numerical method to simulate air flow around a bundle conductor line by means of the FLUENT software is presented and verified by a wind tunnel test for aerodynamic characteristics of a twin bundle conductor line. The lift and drag coefficients of the leeward sub-conductor of a twin bundle conductor varying with its relative position in the wake zone to the windward one under different wind velocities are numerically determined by the presented method. A user-defined subroutine of ABAQUS software is developed to apply the aerodynamic loads on each sub-conductor and the electromagnetic force between sub-conductors. The numerical simulation method for wake-induced oscillation of a bundle conductor line is proposed. By means of the numerical method, wake-induced oscillation processes of twin bundle conductor transmission lines under different parameters, including current intensity, spacer layout, span length and wind velocity, are numerically simulated. Moreover, the effects of those parameters on the oscillation characteristics of the lines, such as vibration mode, frequency, amplitude and motion trace, are discussed. The results obtained provide a fundamental basis for the understanding of wake-induced oscillation behaviour of twin bundle conductor transmission lines and the development of control technique for wake-induced oscillation.