161_1_Lecture_5

161_1_Lecture_5 - EE161 El EE161 Electromagnetic Waves...

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EE161 Electromagnetic Waves all 2010 Fall, 2010 Instructor: Dr. Shenheng Xu Electrical Engineering Dept., UCLA gg p , © Prof. Y. Ethan Wang
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Lecture 5 • Transmission Line • Boundary between Lossy Media • Oblique Incidence: Perpendicular cidence Incidence blique Incidence: Parallel Incidence • Oblique Incidence: Parallel Incidence
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Transmission Line Theory ) ( ), ( z I z V L I z j z j eneral incidence reflection , 0 Z + L Z - L V z j z j e V e V z I e V e V z V 0 0 0 0 ) ( ) ( General solution of TRL z 0 l Z Z 0 0 1 LC 2 Phase constant: LC v p Phase velocity: At z = 0, 0 0 0 0 Z Z Z Z V V L L 0 when , 0 Z Z L Matched! l j At z = -l, l j l j e e V e V l V l V l 2 0 0 ) 0 ( ) ( ) ( ) ( due to the phase advance in the incidence and phase lay in the reflection
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Loaded Transmission Line ) ( ), ( z I z V + L I The input impedance : ratio between the oltage and current looking toward the load , 0 Z L Z - L V z 0 voltage and current looking toward the load from a specified observation plane (for example, z=-l), assuming the source end extends to infinity in Z l The input impedance anywhere in the transmission line can be related to the load impedance at the end l jZ Z l jZ Z Z Z e e Z e V e V e V e V l I l V Z L l j l j l j l j l j l j in tan tan 1 1 ) ( ) ( 0 0 0 2 2 0 ) ( ) ( ) ( 0 ) ( 0 ) ( l L 0 0 0 If f ultiple y r Impedance transformer: , 2 of multiple any or 2 l L in Z Z If ...., 2 , 1 , 0 , n n l in Z Z 2 0 2 4 L Z
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Example: Radar Radome Design Find the thickness of radar ntenna the radome d which causes no reflection! antenna d Radome Incident wave Transmitted wave TRL equivalence! 0 01 Z r Z 02 0 L Z Medium 1 Air, Medium 3 Medium 2, Z=0 Z=-d The minimum thickness is 0 0 r r n n d 2 2 0 2 r d 2 0
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Example: Anti-Reflective Coating coating 2 Find the thickness and the dielectric glass air
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This note was uploaded on 02/09/2011 for the course EE 161 taught by Professor Huffaker during the Spring '08 term at UCLA.

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161_1_Lecture_5 - EE161 El EE161 Electromagnetic Waves...

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