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Published byCory Young Modified over 9 years ago
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TRANSMISSION LINE RESONATORS
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ENEE 482 Spring 20012 Series and Parallel Resonator Circuits L R T Z in C V
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ENEE 482 Spring 20013
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5 Parallel Resonant Circuit
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ENEE 482 Spring 20016
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7 TRANSMISSION LINE RESONATORS LENGTHS OF T.L TERMINATED IN SHORT CIRCUITS Z in Z0Z0 T L R T C
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ENEE 482 Spring 20018
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9 Open Circuited line T Y0Y0 Z in L C T T G
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ENEE 482 Spring 200110
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ENEE 482 Spring 200111 WAVEGUIDE RESONATORS RECTANGULAR WAVEGUIDE RESONATORS RESONANT FREQUENCIES OF TE l,m,n OR Tm l,m,n Z X Y a b c
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ENEE 482 Spring 200112
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ENEE 482 Spring 200113 CYLINDRICAL RESONATORS z D L r CYLINDRICAL WAVEGUIDE RESONATORS RESONANT FREQUENCIES OF TE l,m,n OR Tm l,m,n WHERE:
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ENEE 482 Spring 200114 C L e + - Z in r ZoZo MEASUREMENTS OF CAVITY COUPLING SYSTEM PARAMETERS CAVITY EQUIVALENT CIRCUIT NEAR ONE OF THE RESONANCES
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ENEE 482 Spring 200115 RESONATOR’S Q-FACTORS 2 ENERGY STORED Q = ENERGY DISSIPATED PER CYCLE UNLOADED Q: Q u = 2 f o (L I 2 /2)/(r I 2 /2) = o L/r LOADED Q : Q L = o L/(r + Z o ) = Q u /(1+ Z o /r) COUPLING PARAMETER : Z o /r ; Q u = (1+ Q L EXTERNAL Q : Q E = Q u / Q L = Q u + Q E LOADED Q: INCLUDES ALL DISSIPATION SOURCES UNLOADED Q: INCLUDES ONLY INTERIOR DISSIPATION SOURCES TO CAVITY COUPLING SYSTEM
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ENEE 482 Spring 200116 CIRCUIT PARAMETERS AND DEFINITIONS
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ENEE 482 Spring 200117 RESONATOR’S INPUT REFLECTION COEFFICIENT
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ENEE 482 Spring 200118 DEFINITIONS AND RELATIONSHIPS AMONG THE RESONATOR’S Q’S
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ENEE 482 Spring 200119 AMPLITUDE MEASUREMENTS Magnitude of the reflection coefficient is: The reflection coefficient is:
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ENEE 482 Spring 200120 Reflection Coefficient At Resonance : At Angular Frequency L Where: The Reflection Coefficient is Given By:
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ENEE 482 Spring 200121 MEASURE REFLECTION COEFFICIENT 0 AT RESONANCE DETERMINE L FROM: OR USE CURVE OF L IN dB VS. o IN dB TO FIND L MEASURE THE FREQUENCIES FOR WHICH THE REFLECTION COEFFICIENT IS EQUAL TO L CALCULAT Q L FROM : CALCULATE Q E FROM: THE SIGN TO USE IS DETERMINED FROM THE PHASE OF 0 USE +VE SIGN FOR r < Z 0 AND -VE SIGN FOR r < Z 0
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ENEE 482 Spring 200122 LOCUS OF CAVITY IMPEDANCE ON SMITH CHART NEAR RESONANCE r < Z O r > Z O r = Z O
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ENEE 482 Spring 200123
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ENEE 482 Spring 200124
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ENEE 482 Spring 200125
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ENEE 482 Spring 200126
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ENEE 482 Spring 200127
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ENEE 482 Spring 200128 PHASE MEASUREMENTS MORE SUITABLE FOR LOW Q ( TIGHTLY COUPLED ) SYSTEMS AT FREQUENCY SHIFT u = f o / (2 Q u ), THE IMPEDANCE IS: Z u = r + j r INTERSECTION OF THE LOCUS OF Z u WITH THE LOCUS OF THE CAVITY IMPEDANCE DETERMINES A POINT P u MEASUREMENT OF u AND THE RESONANT FREQUENCY f o YIELDS THE VALUE OF Q u = f o /( 2 u ) AT FREQUENCY SHIFT L = f o / (2 Q L ), THE IMPEDANCE IS: Z L = r + j(Z o + r ) INTERSECTION OF THE LOCUS OF Z L WITH THE LOCUS OF THE CAVITY IMPEDANCE DETERMINES A POINT P L MEASUREMENT OF L AND THE RESONANT FREQUENCY f o YIELDS THE VALUE OF Q L = f o /( 2 L )
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ENEE 482 Spring 200129 PHASE MEASUREMENTS (ctd.) LOCUS OF Z u ON THE SMITH CHART CAN BE SHOWN TO HAVE THE EQUATION: X 2 + ( Y + 1 ) 2 = 2 WHERE X = Re Y = Im LOCUS OF Z u IS A CIRCLE OF CENTER (0,-1) AND RADIUS (2) 1/2 LOCUS OF Z L ON THE SMITH CHART CAN BE SHOWN TO HAVE THE EQUATION: X + Y = 1 WHICH IS A STRAIGHT LINE OF SLOPE -1, PASSING THROUGH THE POINTS (1,0) AND (0,1)
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ENEE 482 Spring 200130 Phase Measurements Locus of Z in Locus of Z U ZoZo r = 0r = 8 PuPu PLPL Locus of Z L
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