Lossy media and power	Feb. 26, 2007

+ Essence of plane waves: wave vector [equation] for arbitrary propagation direction [equation] [equation] with [equation] ; e.g. a plane wave y polarization direction, wave vector [equation] , attenuation [equation] and amplitude = [equation] [equation] , [equation] , [equation] .
Example 2.6: Plane wave method applied to a standing wave

+ TEM wave in lossy media (Sect. 7.3): [equation] and [equation] but now wave impedance [equation] is complex.

+ Applications (pp. 291-295):
a) conductor becomes dielectric at high freq (page 178-181)(assuming [equation] and [equation] not function of [equation] ).
(b) skin depth [equation] .
For good conductors, [equation] .
Example 2.7: Skin depth and attenuation

+ Intensity of a wave (Sec. 7.5): Instantaneous Poynting vector [equation] ([equation] )
Average Poynting vector [equation] , e.g. for plane wave [equation] ; !![equation] !!. Average power [equation]
Example 2.8: Poynting vector

Social and ethical factors in maximum permissible exposure
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HW #10	Due 3/6/07

1. Seawater plays a vital role in the study of submarine communications. Assuming that for seawater, [equation] , [equation] , [equation] and [equation] , calculate (i) the phase velocity, (ii) the wavelength, (iii) the skin depth, (iv) the wave impedance, (v) comment on the effect on skin depth and wave impedance if f is increased to 1GHz.
2. i) Problem 7.10, ii) Use the same way that you solved Problem 7.10 to compute the amplitudes of electric field intensity and magnetic field intensity from the power density given by the IEEE safety standard (check scylla.ceas.uwm.edu/361/Fieldsafe.html) for 100-300MHz under uncontrolled environments as well as controlled environments, iii) compute the power density of a HeNe laser beam with 1mW power and beam radius of 0.5mm by assuming uniform power density across the beam area and does your answer exceed the MPE level for eye safety? (page 331, IEEE standard and laser safety standard at scylla.ceas.uwm.edu/361/Fieldsafe.html).
Extra-credit
A lossy dielectric has an intrinsic impedance of [equation] at a particular frequency. If, at that frequency, the plane wave propagating through the dielectric has the magnetic field component [equation] A/m. Find a) [equation] , b) [equation] , c) [equation] (actually identify it), d) phase velocity in terms of [equation] and e) attenuation coefficient.

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Last Modified: February 25, 2007
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