Microwave Systems

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Microwave Systems

  1. 1. Microwave Systems Microwave Engineering CHO, Yong Heui
  2. 2. Microwave Engineering1. Microwave SystemsTransmission  Information - Channel bandwidth - Base band - Inefficient wave radiation  Modulation – center frequency 출처: RFDH.com Time domain Frequency domain 2 전자파연구실
  3. 3. Microwave Engineering1. Microwave SystemsWhy’s modulation need?  Transmission efficiency - Multiplexing - Antenna length: wavelength - Wave radiation: comparison with DC Battery: DC Antenna: AC 3 전자파연구실
  4. 4. Microwave Engineering1. Microwave SystemsFriis power transmission formula  Microwave radio link R Pt Pr 4 전자파연구실
  5. 5. Microwave Engineering1. Microwave SystemsFriis power transmission formula Pt  Power density: S 2 Gt W / m 2 4 R  Antenna gain: anisotropic radiation (G > 1) isotropic radiation (G = 1) Radiation pattern [dBi]: dB isotropic 5 전자파연구실
  6. 6. Microwave Engineering1. Microwave SystemsFriis power transmission formula  Received power: Pr SAe  Effective area 2 Gr - Ae 4 2 Pr Gt Gr W Pt 4 R  Friis transmission formula 6 전자파연구실
  7. 7. Microwave Engineering1. Microwave SystemsMicrowave transmitter (Tx)  Up-conversion: frequency f BB f LO f BB f LO f BB 출처: RFDH.com 1  cos(x) cos(y) 2 cos(x y ) cos(x y) 7 전자파연구실
  8. 8. Microwave Engineering1. Microwave SystemsMicrowave receiver (Rx)  Down-conversion: frequency 출처: RFDH.com f f LO f IF f f IF f LO f BB f IF f BB f BB 1  cos(x) cos(y) 2 cos(x y ) cos(x y) 8 전자파연구실
  9. 9. Microwave Engineering1. Microwave SystemsMicrowave transceiver  Duplexer: bandpass filter or switch - Loss, tx suppression, channel selection 출처: RFDH.com IF: superheterodyne No IF: direct conversion 9 전자파연구실
  10. 10. Microwave Engineering1. Microwave SystemsUplink and downlink Pt 10[ W ] R 40,000[km]  fd 12[GHz ] θ3dB 2 0.55 Pt 100[ W ] fu 14[GHz ] 4m diameter dish 0.6 10 전자파연구실
  11. 11. Microwave Engineering1. Microwave SystemsUplink calculation 4 DrPr EIRP LFS Gr [dB]  1 2 Gr Dr EIRP Pt Gt 4 2 Dt Ae 4 R 2 LFS Gt Dt 11 전자파연구실
  12. 12. Microwave Engineering1. Microwave SystemsDownlink calculation EIRP Pt GtPr EIRP LFS Gr [dB]  4 Dt 1 2 Gt Dt Dr 4 Am ax 2 2 4 R LFS Gr Dr 12 전자파연구실
  13. 13. Microwave Engineering1. Microwave SystemsThermal Noise or Johnson Noise  Thermal noise: white noise, Nyquist formula Pn kTB N T N N0 B kB  Noise power  Noise temperature 13 전자파연구실
  14. 14. Microwave Engineering1. Microwave SystemsCarrier to noise ratio  C/No: related to carrier to noise ratio  G/T: Figure of merit  Carrier to noise ratio C C C N N0 B TkB  G/T: sensitivity of receiver C EIRP LFS Gr [dB] 14 전자파연구실
  15. 15. Microwave Engineering1. Microwave SystemsMultiplexing: resources  FDM (Frequency Division Multiplexing)  TDM (Time Division Multiplexing)  CDM (Code Division Multiplexing) Communication 15 전자파연구실
  16. 16. Microwave Engineering1. Microwave SystemsFDMA (FDM Access)   Resource: frequency  Guard band  Simple transceiver  Interference 16 전자파연구실
  17. 17. Microwave Engineering1. Microwave SystemsTDMA (TDM Access)  Resource: time  Guard time  Complicated transceiver GSM: Global System for Mobile commo 17 전자파연구실
  18. 18. Microwave Engineering1. Microwave SystemsFH(Frequency Hopping)-CDMA   Resource: code  Precise clock  Very complicated transceiver  Bluetooth, military applications 18 전자파연구실
  19. 19. Microwave Engineering1. Microwave SystemsDS(Direct Sequence)-CDMA QPSK: Quadrature Phase Shift Keying 19 전자파연구실
  20. 20. Microwave Engineering2. ApplicationsFrequency spectrum Name Frequency[Hz] Wavelength Application EHF 30G-300G 1cm-1mm Car radar SHF 3G-30G 10cm-1cm Radar, satellite UHF 300M-3G 1m-10cm TV, PCS, IMT2000 VHF 30M-300M 10m-1m FM, TV HF 3M-30M 100m-10m Shortwave AM, HAM MF 300k-3M 1km-100m AM LF 30k-300k 10km-1km Navigation VLF 3k-30k 100km-10km Submarine, navigation ELF 30-300 10000km-1000km Submarine 20 전자파연구실
  21. 21. Microwave Engineering2. ApplicationsAttenuation  HF application  Attenuation by water and oxygen 21 전자파연구실
  22. 22. Microwave Engineering2. ApplicationsELF application  Skin depth: long wavelength  Long antenna: 104km at USA  Unidirectional communication  Slow bit rate: redundancy  Information: code table 2 1 22 전자파연구실
  23. 23. Microwave Engineering2. ApplicationsEHF application  Short antenna  Absorption: air, water(60 GHz)  Anti-collision radar: 76 GHz  ITS: Intelligent Transport System Radar ITS 23 전자파연구실

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