Testing of digital systems has been widely researched and studied. Many test methods have been developed and used. However, traditional voltage and current testing are not sufficient in modern integrated circuit (IC) design. This paper introduces a new method using electromagnetic field (EMF) generated from a circuit, which can be used to detect and diagnose possible faults in millimeter scale circuit. CST Microwave Studio and SONNET EM simulator are used to simulate detection of magnetic field intensity above several microstrip lines which are shorted and opened. Furthermore, the models have been fabricated on FR4 and measured the transmission coefficients by Network Analyzer. Both simulation and measurement show that faults in circuits result in high Standing wave for both short and open cases. Open line tends to induce higher Standing Wave (SW) than short line. © 2011 IEEE.