Electromagnetic field predictions inside screened enclosures containing radiators

• Published in: EMC York 99. International Conference and Exhibition on Electromagnetic Compatibility pp. 95 - 100
• Main Authors: Konefal, T, Dawson, J.F, Denton, A, Benson, T.M, Christopoulos, C, Marvin, A.C, Porter, S.J, Thomas, D.W.P
• Format: Conference Proceeding
• Language: English
• Published: London IEE 1999
• Subjects: Applied sciences; Electric and magnetic fields; Electromagnetic compatibility and interference; Electronic equipment and fabrication. Passive components, printed wiring boards, connectics; Electronics; Exact sciences and technology; Packaging; Printed circuits; Product packaging; Waveguide and cavity theory; electromagnetic field predictions; mode coupling; printed circuits; short circuited lines; apertures; electric dipole; magnetic dipole; magnetic moments; screened enclosures; electric impedance; electric fields; UHF; experiment; electric monopoles; higher order modes; TE10 waveguide mode; radiators; magnetic fields; electromagnetic shielding; packaging; transmission lines superposition; internal impedances; transmission lines; PCB; waveguide theory; cut off frequency; electromagnetic fields; 600 MHz; electromagnetic coupling; rectangular waveguides; rectangular waveguide; Experimental result; Mode coupling; Transmission line; Printed circuit board; Electromagnetic compatibility; Electric dipole; Magnetic dipole; TE mode; Modeling; Containment confinement; Rectangular waveguide
• ISBN: 0852967160; 9780852967164
• ISSN: 0537-9989
• DOI: 10.1049/cp:19990251

In order to understand how a PCB inside an enclosure with apertures radiates externally, it is first necessary to understand how the PCB excites the environment internal to the enclosure. This paper describes a simple method which can be used to predict the electric and magnetic fields within a screened enclosure, treating the PCB as a combination of electric and magnetic dipoles with internal impedances. The enclosure is treated as a superposition of transmission lines (one for each waveguide mode) which are short circuited at each end. Mode coupling is taken into account in both the magnetic and electric cases. The method is used to predict the coupling between two loops which are introduced into the enclosure, and also between two electric monopoles which are introduced into the enclosure. Good agreement with experiment is found below 600 MHz (approximately twice the lowest cut off frequency), by considering only the TE10 waveguide mode. Agreement at higher frequencies is qualitatively good, and is improved further by taking into account one or two higher order modes.