Lecture4

Lecture4 - Wireless Communications Technology Antennas and...

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EE475 DR. Kirkman Lecture 4 USC 1 Wireless Communications Technology Antennas and Propagation Dr. George Kirkman EE475 Fall 2006
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EE475 DR. Kirkman Lecture 4 USC 2 Waves in Free Space ] Re[ 2 1 )] , ( ˆ ) , ( ˆ [ ) , , ( * 0 0 0 S S H E S E H E H r e F F r E avg r jk = × = = - = + = - η φ θ TEM wave = 377 0 Free space wave impedance
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EE475 DR. Kirkman Lecture 4 USC 3 Antenna An antenna is an impedance transformer that transforms waves from guided propagation at characteristic impedance Z 0 to free space propagation at η 0 Z 0 η 0 Antenna
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EE475 DR. Kirkman Lecture 4 USC 4 Far Field Distance at which the waves can be described by Equations on slide 2 (Eq 4.1 in text ) Approximate plane waves An approximation! Z 0 Antenna D Far Field λ 2 2 D R ff =
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EE475 DR. Kirkman Lecture 4 USC 5 Radiation pattern ) log( 10 ) ( 4 4 2 max max D dB D A D P U D rad = = = λ π Directivity A is antenna Aperture or effective Aperture
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EE475 DR. Kirkman Lecture 4 USC 6 Antenna Gain A measure of directivity and efficiency Includes any losses in antenna ) log( 10 ) ( G dB G D e G rad = =
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EE475 DR. Kirkman
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This note was uploaded on 04/09/2010 for the course EE 475 taught by Professor Kirkman during the Spring '07 term at USC.

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Lecture4 - Wireless Communications Technology Antennas and...

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