ELE444_Lec_6_new.pdf - ELE 444 Antennas and Propagation Lecture 6 Fundamental Parameters of Antennas(part 4 Prof Dr \u00d6zlem \u00d6zg\u00fcn H\u00dc-EEE \u00d6 \u00d6zg\u00fcn

ELE444_Lec_6_new.pdf - ELE 444 Antennas and Propagation...

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-EEEÖ. ÖzgünELE 444 ANTENNAS AND PROPAGATION1Lecture 6:Fundamental Parameters of Antennas (part # 4)ELE 444 Antennas and PropagationProf. Dr. Özlem ÖzgünPhone:297-70-70E-mail:[email protected]Web:
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-EEEÖ. ÖzgünELE 444 ANTENNAS AND PROPAGATION2Antenna ParametersRadiation Pattern (or Antenna Pattern)BeamwidthRadiation Power DensityRadiation IntensityDirective Gain and Directivity Beam Solid AngleBeam EfficiencyGainAntenna EfficiencyPolarizationEffective Area Friis Transmission Equation Radar Range Equation and Radar Cross Section (RCS)Input Impedance Radiation ResistanceBandwidthAntenna Noise Temperature
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-EEEÖ. ÖzgünELE 444 ANTENNAS AND PROPAGATION3Input Impedance and Radiation ResistanceAntenna is like a resonator ! (RLC circuit)At resonant frequency, capacitive and inductive reactances cancel each other, and“antenna is purely resistive. Power radiated by the antenna is maximum at the resonant frequency.Radiation resistance!1LCReactance
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-EEEÖ. ÖzgünELE 444 ANTENNAS AND PROPAGATION4Input Impedance and Radiation ResistanceWire antenna resonates if length=/2 (or odd-multiples)Low impedance feed point which is convenient to match.Radiation increases due to low impedance of the antenna./23/2
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-EEEÖ. ÖzgünELE 444 ANTENNAS AND PROPAGATION5Input Impedance and Radiation ResistanceRadiation resistance (Rr)is the value of“fictitious”resistance thatwould dissipate (radiate into space) an amount of power accordingto the maximumcurrent at the input terminals of an antenna.A high radiation resistance is desirable!2rad terminalr1PIR2avSSWdsU d
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-EEEÖ. ÖzgünELE 444 ANTENNAS AND PROPAGATION6Input Impedance and Radiation ResistanceZgZA
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-EEEÖ. ÖzgünELE 444 ANTENNAS AND PROPAGATION7Input Impedance and Radiation Resistance
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-EEEÖ. ÖzgünELE 444 ANTENNAS AND PROPAGATION8Input Impedance and Radiation Resistance*221powerRe21122V IVIRR
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-EEEÖ. ÖzgünELE 444 ANTENNAS AND PROPAGATION9Input Impedance and Radiation Resistance*AGZZ*2AgZZggggLrgLrAgVVIIRRRRRj XX
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