Using image planes on DC motors to filter high frequency noise

Traditionally, DC motors have only been filtered for narrow frequency bands of interest, such as the AM and FM bands. However, as more electronic devices are implemented in consumer applications such as automobiles, requirements now demand filtering from kilohertz to several gigahertz. Capacitors, inductors, and ferrites characteristically are used to filter narrow frequency bands. They are limited by their size and parasitics for broadband performance and are cost prohibitive in many DC motor applications that require broadband performance. The paper investigates an alternative cost effective approach for broadband filtering performance. Image planes have been shown to provide good results on PCB applications for reducing radiated emissions. The paper examines the possibility of using image theory for filtering DC motors.