Electromagnetic Lanjutan SAP Dari buku Stuart Wentworth: • Pertemuan 10 Plane Waves: 5.1 -5.4 • Pertemuan 11 Plane waves: 5.5 – 5.8 Dari buku Stuart: • Pertemuan 12 Transmission lines: 6.1 - 6.3 • Pertemuan 13 Transmission lines: 6.4 - 6.5 • Pertemuan 14 Transmission lines: 6.6 - 6.8 • Pertemuan 15 Waveguide : 7.1 -7.2 • Pertemuan 16 Waveguide : 7.3 -7.4 • Pertemuan 17 Waveguide : 7.5 -7.6 • Pertemuan 18 Antena : 8.1 - 8.4 • Pertemuan 19 Electromagnetic Interference: 9.1 – 9.3 • Pertemuan 20 Electromagnetic Interference: 9.4 – 9.6 Figure 2-47 (p. 77) Simplified schematic of an electret microphone circuit. Figure 3-34 (p. 136) Cross section of a moving-coil loudspeaker. Fundamentals of Electromagnetics With Engineering Applications by Stuart M. Wentworth Copyright © 2005 by John Wiley & Sons. All rights reserved. Figure 3-53 (p. 159) Maglev prototype. Courtesy of Transrapid International. Fundamentals of Electromagnetics With Engineering Applications by Stuart M. Wentworth Copyright © 2005 by John Wiley & Sons. All rights reserved. Figure 3-54 (p. 160) The Maglev concept. Fundamentals of Electromagnetics With Engineering Applications by Stuart M. Wentworth Copyright © 2005 by John Wiley & Sons. All rights reserved. Plane Waves Learning Objectives • Derive the general equations for electromagnetic wave propagation • Study electromagnetic wave propagation in conductors and define skin depth • Describe electromagnetic wave power transmission using the Poynting theorem • Define the polarization of an electromagnetic wave • Study reflection and transmission of waves incident from one material to another Figure 5-1 (p. 210) At a remote distance away from a point source, the waves appear to be planar. Fundamentals of Electromagnetics With Engineering Applications by Stuart M. Wentworth Copyright © 2005 by John Wiley & Sons. All rights reserved. 5.1 General Wave Equations • Material media that are linear, isotropic, homogeneous and time invariant Figure 5-2 (p. 217) Representation of waves. In (a), the wave travels in the ap = +az direction and has Es = E0+e-yz ax and Hs = (E0+/)e-z ay. In (b), the wave travels in the ap = –az direction and has Es = E0-ez ax along with Hs = –(E0-/)ez ay. Fundamentals of Electromagnetics With Engineering Applications by Stuart M. Wentworth Copyright © 2005 by John Wiley & Sons. All rights reserved. 5.2 Propagation in Lossless, ChargeFree Media • Charge-free (v = 0) medium has zero conductivity( = 0 ) • perfect dielectric is lossless 5.3 Propagation in Dielectrics • Dielectrics are to some degree lossy • The lossy nature can be attributed to finite conductivity, polarization loss or a combination of the two. • Low loss dielectrics is one with a small loss tangent (/<<1) A standard measure of lossiness in a dielectric is given by the loss tangent. It is useful for classifying a material as either a good dielectric (tan <<1 ) or a good conductor (tan >>1 ) Figure 5-3 (p. 222) Loss tangent tan is the ratio of the conduction to displacement current densities, or tan = (+”) ’. Fundamentals of Electromagnetics With Engineering Applications by Stuart M. Wentworth Copyright © 2005 by John Wiley & Sons. All rights reserved. 5.4 Propagation in Conductors • In any decent conductor at reasonable frequencies the loss tangent, / , is much greater than one. • Example, stainless steel with a conductivity of 106 S/m. Figure 5-5 (p. 225) The portion of an electromagnetic wave incident from air that passes into a conductor experiences high attenuation and a decrease in wavelength. Fundamentals of Electromagnetics With Engineering Applications by Stuart M. Wentworth Copyright © 2005 by John Wiley & Sons. All rights reserved. Figure 5-6 (p. 226) Slab of material with length L, width w, and thickness t has conductivity . The top and bottom faces are covered in equipotential surfaces tied to a voltage supply. Fundamentals of Electromagnetics With Engineering Applications by Stuart M. Wentworth Copyright © 2005 by John Wiley & Sons. All rights reserved. Figure 5-7 (p. 227) An x-polarized electric field is incident on a semiinfinite slab of material that occupies z > 0. Fundamentals of Electromagnetics With Engineering Applications by Stuart M. Wentworth Copyright © 2005 by John Wiley & Sons. All rights reserved. Figure 5-8 (p. 228) The total area under the e-z curve from z = 0 to infinity) is equal to the product of Exo and . Fundamentals of Electromagnetics With Engineering Applications by Stuart M. Wentworth Copyright © 2005 by John Wiley & Sons. All rights reserved. Figure 5-9 (p. 229) Plot showing the accuracy of the calculated skin-effect resistance as a function of slab thickness. Fundamentals of Electromagnetics With Engineering Applications by Stuart M. Wentworth Copyright © 2005 by John Wiley & Sons. All rights reserved. Figure 5-10 (p. 230) Coaxial cable indicating current is confined to within a skin-depth of the conductor surfaces. Fundamentals of Electromagnetics With Engineering Applications by Stuart M. Wentworth Copyright © 2005 by John Wiley & Sons. All rights reserved. Latihan 5.3: A wave with l = 6.0 cm in air is incident on a nonmagnetic, lossless liquid media. In the liquid, the wavelength is measured as 1.0 cm. What is the wave’s frequency (a) in air? (b) in the liquid? (c) What is the liquid’s relative permittivity? Answer (a) 3x108 m s f 5GHz 0.06m up c (b) the frequency doesn’t change with the media (the wavelength does) so f = 5 GHz (c) c 9 1 7 m u p f 5 x10 0.01m 5 x10 s 2 3x10 r 36 8 0.5 x10 8 s r Terima kasih Selesai