Magnetic and electric field radiation of bent microstrip line using Hertzian dipole method

Electromagnetic Interference (EMI) and Signal Integrity (SI) issues have generated challenges to the high speed digital circuit designers as the operating clock frequency of the system continue to increase to accommodate broadband applications. Discontinuity due to microstrip bents which appear frequently in most VLSI design requires thorough understanding on the current distribution in order to generate the immunity and emission characteristic of the circuit. The focus of this paper is on the bent microstrip transmission line based on the forward-backward travelling wave mode method (TWM) by Xilei Liu et al [6]. Their approach is modified with the adoption of equivalent wire model to suit for the case of microstrip line. The expanded Hertzian dipole formulations are used to determine the inadmissible radiated emission that annoys the external circuits. Computer simulation using MICROWAVE STUDIO® is implemented for validation of the modelling technique. The effects of termination scheme, operating frequency and trace width on the radiated emission of bent microstrip line are discussed.