Figure 1. Figure 2. Figure 3. LIST OF FIGURES Curve of equal TE01 and TE10 cutoff frequencies for a Normalized TE01 cutoff wavelength for a transverse .14 ...15 Electromagnetic field distortion due to a metallic cut in a transverse electromagnetic cell (electrostatic approximation). 16 Figure 4. Coordinate system of a rectangular cylinder in a 17 Figure 5. Magnetic field distortion due to a perfectly conducting 18 Figure 6. Magnetic field distortion due to a perfectly conducting cylinder (width = 18 cm, height h = 5.5 cm) in a transverse electromagnetic cell at 2 MHz....... ...19 Figure 7. Magnetic field distortion due to a perfectly conducting cylinder (width = 18 cm, height h = 5.5 cm) in a transverse electromagnetic cell at 5 MHz.... ..20 Figure 8. e Magnetic field distortion due to a perfectly conducting cylinder (width = 18 cm, height h = 5.5 cm) in a transverse electromagnetic cell at 10 MHz.. Magnetic field distortion due to a perfectly conducting cylinder (width = 18 cm, height h = 5.5 cm) in a transverse electromagnetic cell at 50 MHz... 22 Figure 10. e Magnetic field distortion due to a perfectly conducting cylinder (width = 18 cm, height h = 5.5 cm) in a transverse electromagnetic cell at 100 MHz.............23 Magnetic field distortion due to a perfectly conducting cylinder (width = 18 cm, height h = 15 cm) in a transverse electromagnetic cell at 2 MHz.... Magnetic field distortion due to a perfectly conducting cylinder (width = 18 cm, height h = 15 cm) in a Magnetic field distortion due to a perfectly conducting cylinder (width = 18 cm, height h = 15 cm) in a transverse electromagnetic cell at 10 MHz.. ..26 Figure 14. Magnetic field distortion due to a perfectly conducting cylinder (width = 18 cm, height h = 15 cm) in a transverse electromagnetic cell at 50 MHz..... 27 Figure 15. Magnetic field distortion due to a perfectly conducting cylinder (width = 18 cm, height h = 15 cm) in a transverse electromagnetic cell at 100 MHz..... .28 Figure 16. Magnetic field distortion due to a perfectly conducting cylinder (width = 18 cm, height h = 25 cm) in a transverse electromagnetic cell at 2 MHz... .29 Figure 17. Magnetic field distortion due to a perfectly conducting cylinder (width = 18 cm, height h 25 cm) in a transverse electromagnetic cell at 5 MHz... = ..30 Figure 18. Magnetic field distortion due to a perfectly conducting cylinder (width = 18 cm, height h = 25 cm) in a transverse electromagnetic cell at 10 MHz..............31 Figure 19. Magnetic field distortion due to a perfectly conducting cylinder (width = 18 cm, height h = 25 cm) in a transverse electromagnetic cell at 50 MHz... .32 Figure 20. Magnetic field distortion due to a perfectly conducting cylinder (width = 18 cm, height h = 25 cm) in a transverse electromagnetic cell at 100 MHZ..... .33 Figure 21. Magnetic field distortion at the center of the top of the cylinder as the ratio of its height to the separation distance of the parallel plate waveguide at 2 MHz......34 Figure 22. Figure 23. Figure 24. Figure 25. Magnetic field distortion at the center of the top of the cylinder as the ratio of its height to the separation distance of the parallel plate waveguide at 5 MHz......35 Magnetic field distortion at the center of the top of the cylinder as the ratio of its height to the separation distance of the parallel plate waveguide at 10 MHz.....36 Magnetic field distortion at the center of the top of the cylinder as the ratio of its height to the separation distance of the parallel plate waveguide at 50 MHz.....37 Magnetic field distortion at the center of the top of the cylinder as the ratio of its height to the separation distance of the parallel plate waveguide at 100 MHz....38 Figure 26. Electric field distortion at the center of the top of the cylinder as the ratio of its height to the separation distance of the parallel plate waveguide.. ...39 Figure 27. Figure 28. Simultaneous electric and magnetic field measurements using a doubly-loaded electrically small loop. Phase degradation of the TEM mode as the ratio of ..40 ..41 Theoretical and Experimental Investigations of Electromagnetic Field Distortion Due to a Perfectly Conducting Rectangular Cylinder in a Transverse Electromagnetic Cell The study of electromagnetic compatibility (EMC), that is the electronic and biological effects due to electromagnetic (EM) radiation, and EM calibration require accurate EM measurement techniques for defining the EM interference (EM) characteristics. Thus, fully enclosed rectangular transverse electromagnetic (TEM) transmission lines with thin inner conductors are often often used for generating standard known test fields. In all cases it is desirable that only the dominant TEM mode should propagate. In the EMC measurements, an object under test is placed inside of a TEM cell. The field from the TEM mode incident upon this scattering object is identical to that of a plane wave in a free space. However, the scattered field produced by the object in the TEM cell is different from the scattered field produced by the object in a free space, because of multiple reflections from the TEM cell walls, or equivalently, the mutual coupling between the object and the TEM cell. The purpose of this paper is to discuss the loading effects, i.e., the electromagnetic field distortion caused by an object under test in a TEM cell. In the theoretical analysis, the frequency domain integral equation for the magnetic field, or equivalently, the current density on the surface of a perfectly conducting cylinder in a parallel plate waveguide is solved by the method of moments to predict the degree of magnetic field distortion . The experimental investigations are performed by mounting a number of electrically small half loops on the surface of the the perfectly conducting cylinder in in a TEM cell. The loading effects in terms of magnetic field distortion are analyzed as the ratio of one of the object dimensions (height) to the separation distance between the inner conductor and the ground plane of the TEM cell. Also, the response of an electrically small loop to both the magnetic and electric components of the electromagnetic field is used to measure the phase relation between the Keywords: Electromagnetic Compatibility (EMC); Green's I. INTRODUCTION The study of electromagnetic compatibility (EMC), that is the electric and biological effects due to electromagnetic (EM) radiation, and EM calibration require accurate EM measurement techniques for defining the EM interference (EMI) characteristics. Thus, fully enclosed rectangular transverse electromagnetic (TEM) transmission lines with thin inner conductors are often used for generating standard known test fields. In all cases, it is desirable that only the dominant TEM mode should propagate. Thus, the usefulness of these structures is limited to a frequency region below some upper frequency bound in order to suppress the higher order modes. The higher order mode cutoff frequencies of the rectangular TEM cell have been well studied by many workers [1,2,3,4]. While in a rectangular hollow waveguide, the dominant mode is always the TE10 mode as long as the width exceeds the height, the same conclusion does not hold for the rectangular line with an inner conductor even if its thickness is infinitesimally small. In fact, it is found [1,2,4] that, depending on the width of the inner conductor and the size of the TEM cell, the cutoff frequency of the TE01 mode can be much lower than that |