ece312_au10_exam2sol

ece312_au10_exam2sol - ECE 312 — Autumn Quarter 2010 Exam...

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Unformatted text preview: ECE 312 — Autumn Quarter 2010 Exam #2 November 12th, 2010 Write your name below and sign the honor pledge “No aid given, received, or observed” if it applies. ' There are 3 problems on this exam. Exam is open book and notes. Please box or underline your final answers, and remember to include units. Be sure to Show all work clearly if you wish to obtain any partial credit. Try to keep your work within the provided space. Use the back of a previous sheet if necessary. Name: St: iwfikefi “The Pledge”: No aid given, received, or observed Problem 1 [3 parts, 40 pointsl A linearly polarized plane wave propagating in free space has wavelength 5 m and propagates it + 3“; J2 (a) Write a phasor electric field that has these properties (there are many possible answers). Provide numerical values for the quantities in your expression. (13 points) in direction . The electric field amplitude is 0.2 V/m. magnum , tau... awmsflwdqrflwam E; “or was {3%an m «~31. .. '(b) Find the time domain magnetic field that corresponds to your plane wave. Again provide numerical values for the quantities in your expression (if not already provided in part (21)). (14 points) m E; $3 an a; x“ g I m flat file a villa salariw wait areas )3 w. Mae AA ‘7‘; :1 «Jr J;- $%“>Qe E @733 afi‘iiaéffizrg xfi; d—mm. is ex"- A g « “Mia s g staafléfifi r, W W K A J \fia _ EQ akafiflm it» Egg E ajMEMaieQ m [fly I I If“ ,. airth tWilli:finanffitt {we} W t a m fiiaaiairiafig a" $fi§xéa§ swim, ‘ (c) Find the time averaged Poynting vector associated with your plane wave. Include both magnitude (a numerical value) and direction. Feel free to use any simplified equations for this quantity if applicable.(13 points) TMaA‘ss a. stage dam, mm imeiwiwmwém as; Problem 2 {3 parts: 36 p oints) A 181.6 MHZ plane wave is obliquely incident from amedium having a = 25 so, u = no , o = 0 (Region 1) onto aboundary with a medium having 8 = 480, u = no, and c5 = 0 (Region 2). It is known that the eiectrie field in the transmitted region has the form 21' 7‘ 7 E = 5223 14% “)2 (V/rn) Note the symbols 9i , BB, and 96 refer to the incidence, Brewster, and critical angles respectively. I (a) Is the incident wave perpendicular or parallel polarized or a combination? (7 points) Tim M; ‘ i R I A fig“; RM vi % &\m§gm “fir that its gag-i Nae {M’Q‘Er in leads ram rag Mug" Ex“ "3"; Q ¥te “ring” $ng (b) Which is true? (a) 9i S 90 (b) 9i > BC (0) There is no critical angle in this configuration (7 points) (c) What fiaction of the incident power density is reflected? HINT: This problem requires no computations. (7 points) (d) Find 91.. (15 points) Problem 3 :6 partsz 4 points each}: Circle the best answer. (1) A plane wave is propagating in a lossy medium. What is the skin depth in the medium if the plane wave power density attenuates 23 H tee of 33 cm? (a) 1.59 cm (b) 6.29 cm “m (d) 21.09 cm (6) none of the above “a; refighters, mm :- w as Sehw‘te“§"§$§“ an alt“ ta“ WW- (2) A plane wave is obliquely incident from free space onto a boundary with a medium having a = 780 , u = no , and (5 i 0 . No reflected wave is observed. Which of the following is true? “xg9r¥w74F(W.:fipmw‘&p13,53v)?«g-W3Y5Ww1i'xni5fiimmfifimfiv‘w flpgmw1wnfismmw - San-am... m www.mwwaarfimgwgmufi V v )— N 4;. O B wrn-awwaeva is. g a as la. (b) the incident fieldmi‘sxpfleffifléifidiiifilafpdlafiied' and the incidence angle is 69.3 degrees a (c) the incident field is parallel polarized and the incidence angle is 20.7 degrees “1:. g9 (d) the incident field is perpendicular polarized and the incidence angle is 20.7 degrees (6) nOne of the above *jfix (3) A plane wave has electric field (sz + (j + 1).?)9 (V/In). Thepolarization of this field is: (a) linear (b) left handed circular (0) right handed circulari (d) elliptigalgl (6) none of the above «WM " (4) A 9.7 GHZ plane wave is normally incident from free space onto a medium having a = 250 , n = no, and c; = 0.3 Wfiacfion of the incident power density is reflected? y. (a) 0.0294 7&0.0372 (c) 0.0723 (d) 0.0963 (c) none of the above .... . m; er” 4. .. ' Q“ gait; ‘3 @aahzéelgsfiwwfi ii»: We e. as tweet. \fixgt'iQEEfl (5) Under the good conductor approximation, filt’wh tag ‘5‘ 9 (a) the skin depth is equal to the wavelength (b) the skin depth increases as the frequency increases (c) the complex propagation constant is purely real (6) A 4 GHz plane wave propagating in a lossless medium has wavenumber 400 rads/m. The phase velocity of this plane wave is: (a) 3 X 108 m/s .39 . l ‘ % (b) 7.50x107 rn/s kt; “g as m m a" “t k} m '9‘ .-,. _ id. 7 M: a? p g M .. as was (0) 6.28 x 10 _ WWWManMAmQ£MM W(d)3 x 107 (e) none of the above ...
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ece312_au10_exam2sol - ECE 312 — Autumn Quarter 2010 Exam...

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