1036 PIERS Proceedings, Moscow, Russia, August 19–23, 2012 Design of Stripline Structure for Electromagnetic Characterization at Microwave Frequency Ellen Yoshie Sudo Lutif 1, 2 , Anderson Kenji Hirata 2 , Alberto Jos´ e de Faro Orlando 1 , and Antonio Carlos da Cunha Migliano 1, 2 1 Aerospace Technological Institute (ITA), CTA, Brazil 2 Institute of Advanced Studies (IEAv), CTA, Brazil Abstract— A comprehensive approach to the design of a stripline for EMC testing is given in this paper. The authors attention has been focused on the design items that are most crucial by the achievement of satisfactory value of the VSWR and impedance. The characteristic impedance of the stripline test section should be smoothly matched with the feed and terminations points in order to minimize the standing waves. Thereby, the most critical parameters that directly determine the physical design of the stripline are impedance matching at the feed port (S 11 parameter) and transmission between two ports (S 21 parameter). An analysis can be performed for the stripline configuration using a vector network analyzer. A measurement of the reflection from transmission through a material along with knowledge of its physical dimensions provides the information to characterize electromagnetic waves at microwave frequencies range. 1. INTRODUCTION Typical striplines are constructed to have an impedance of either 50 Ω or 90 Ω. The ratio between the width of the active conductor and the height of the active conductor and the height of the active conductor above the ground plane determines the characteristic impedance. The design given in this paper is focused on the 50 Ω stripline. Today in communication systems the use of magnetic and dielectric materials exceeds the usual fields of application (randomes, antennae, microwave circuits, . . . ). New components are developed to meet the demand of leading areas. This is the case for materials absorbing the electromagnetic energy, which are used for microwave electromagnetic compatibility (EMC). A vector analyzer is a versatile measurement system, which comprises of a two or four channels for microwave receiver designed to process the magnitude and phase of transmitted and reflected waves of the network. It directly displays the S -parameters of passive and active networks at the desired frequency range. With advancement of technology, VNA are available now with full range of parameters to be measured like S -parameters in magnitude (dB)/phase form, real/imaginary form, as well as in the linear form, VSWR, Group delay, impedance, etc.. When dealing with vector measurement quantities, such as complex reflection and transmission coefficients (i.e., S -parameters) in RF and microwave metrology, several important factors need to be considered such as the expression form of the complex quantities (either in the real and imaginary components or magnitude and phase components) and correlation between these components [1]. Earlier the magnitude and phase form of complex S -parameter was selected as the measurand. The uncertainties in the magnitude and phase form of the VNA measurements have been studied and reported earlier [2]. The mathematical model for determining the measurement uncertainty depends on the type of measurand. The studies showed an ambiguity in the phase measurement, where phase depends highly on the structure and application of device under test (DUT) as well as the operating frequency. To avoid the problems during the statistical analysis of complex quantities in the magnitude/phase form, the real and imaginary form has been chosen to analyze the complex quantities. In this form, the real and imaginary components of complex S -parameter are correlated, so their covariance also contributes to the uncertainty. 2. THEORY 2.1. Stripline Design A stripline consists of upper and down grounding plates, and the central conductor. Between the grounding plates and the central conductor is air or dielectric materials. The fundamental propagation mode for a stripline is TEM. For the TEM wave propagation in a stripline, the phase velocity is: v p = c √ ε r (1)