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ELCT564 Spring 2013

ELCT564 Spring 2013. Introduction to Microwave Engineering. RF and microwave engineering covers frequency from 100 MHz to 1000GHz. VHF. RF frequencies: 30-300 MHz. UHF. RF frequencies: 300-3000 MHz. Microwave frequencies: 3-300 GHz. mmwave frequencies: 30-300 GHz.

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ELCT564 Spring 2013

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  1. ELCT564 Spring 2013 ELCT564

  2. Introduction to Microwave Engineering RF and microwave engineering covers frequency from 100 MHz to 1000GHz VHF RF frequencies: 30-300 MHz UHF RF frequencies: 300-3000 MHz Microwave frequencies: 3-300 GHz mmwave frequencies: 30-300 GHz THz frequencies: >300 GHz ELCT564

  3. Why study them separately? Region of EM spectrum where neither standard circuit theory (Kirchoff) nor geometrical (ray) optics can be directly applied. Because of short wavelength, lumped element approximation cannot be used. Need to treat components as distributed elements: phase of V or I changes significantly over the physical length of a device For optical engineering λ << component dimensions ELCT564

  4. Approach Solve Maxwell’s equations and apply boundary conditions for the specific geometry. Hard to do for every device!!!! Analytical solutions exist only for some basic geometries and often must use numerical techniques In a lot of cases we can find V, I, P, Zo by using transmission line theory (use equivalent ckts) Not a lot of info on EM fields but sufficient for microwave and RF circuits As f increases need to use full-wave tools ELCT564

  5. Why study microwaves? More bandwidth or information can be realized at higher frequencies – essential for telecommunications Microwave/mm-wave travel by line-of-sight and are not bent by the ionosphere (such as AM signals) Most of them not affected by atmospheric attenuation (space com. or secure terrestrial com.) Higher resolution radars are possible at higher frequencies Various atomic & molecular resonances occur mwave/mm-wave/THz frequencies which are important for remote sensing, radio astronomy, spectroscopy, medical diagnostics, sensing of chemical.biological agents Can get a very good salary as an RF/mmwave engineer. ELCT564

  6. Applications Patriot Defense System Surface Radar ELCT564

  7. Applications Global Communication Systems for the Army Air Traffic Control ELCT564

  8. Applications Global Positioning System Personal Communication Systems Wireless LANs ELCT564

  9. Applications Monolithic Microwave/mm-wave Integrated Circuits MRI Remote Sensing Earth and Space Observations ELCT564

  10. Applications Cable and Satellite TV Aircraft and Automobile Anti-Collision Radar ELCT564

  11. ELCT564

  12. 94 GHz Emerging High Frequency Applications Personal Communications High speed microprocessor Satellite 60-G Wireless HDMI Point-to-point/Multi-point links Mobile Computing/WLAN Adaptive cruise control radar for automobiles DVD player Automotive Radar ELCT564

  13. Home Networks of the Future ELCT564

  14. Access to PSTN Connected to Home Office Wireless Service Providers Global Deployment Access to Corporate Networks Access to Internet Service Providers Wireless Market Segmentation Enables Video Applications ELCT564

  15. Wireless Engine ELCT564

  16. System Integration Basic Electromagnetics RF/Wireless Education: Multi-Disciplinary Device/Circuit Design • Integration Concepts • Advance CAD Techniques • Current Technologies and Design Rules • Modern Experimental Analysis for Circuits and Subsystems ELCT564

  17. Transmission Lines “Heart” of any RF/Wireless System Parallel-Plates Coaxial Cable Twisted-Pair Rectangular Waveguide ELCT564

  18. Transmission Lines Microstrip Coplanar Waveguide ELCT564

  19. Substrate Materials • Semiconductors • Organic • Ceramics • Glass ELCT564

  20. Advanced Printed Wiring Board Technology

  21. Transmission Line Equivalent Circuit i(z+Dz,t) i(z,t) L Dz R Dz + + u(z+Dz,t) u(z,t) C Dz G Dz - - Dz

  22. Microwave Bands

  23. EM Theory Review ELCT564

  24. Maxwell’s Equations ELCT564

  25. Fields in Media Loss tangent ELCT564

  26. Dn2 Dn2 Et2 ..... Bn2 Fields at General Material Interface Ht2 Dn1 Et1 Medium 2 ..... h Ht1 Bn1 Medium 1 Dn1 ELCT564

  27. h Et2 Medium 2 Msn Fields at General Material Interface Et1 Medium 1 ELCT564

  28. Fields at a Dielectric Interface Fields at the Interface with a Perfect Conductor Fields at the Interface with a Magnetic Wall ELCT564

  29. The Helmholtz Equation Source-free, linear, isotropic, homogeneous Wave Equation/The Helmholtz Equation Propagation constant/phase constant/wave number ELCT564

  30. Plane Waves in a Lossless Medium Assuming electric filed only have x component and uniform in x and y directions Phase velocity What is the speed of light? Wavelength Intrinsic Impedance ELCT564

  31. Plane Waves in a General Lossy Medium Complex propagation constant: Attenuation constant and phase constant ELCT564

  32. Plane Waves in a General Lossy Medium ELCT564

  33. Plane Waves in a Good Conductor The amplitude of the fields in the conductor decays by an amount 1/e (36.8%) after traveling a distance of one skin depth 8.14×10-7m 6.60×10-7m 7.86×10-7m 6.40×10-7m ELCT564

  34. Summary of Results for Plane Wave Propagation in Various Media ELCT564

  35. General Plane Wave Solutions i=x,y,z Separation of variables ELCT564

  36. Circularly Polarized Waves Polarization of a plane wave refers to the orientation of the electric field vector: fixed direction or change with time. The plane waves which have their electric filed vector pointing in a fixed direction are called linearly polarized waves. Electric field polarization for (a) Right Hand Circularly Polarized (RHCP) and (b) Left Hand Circularly Polarized plane waves. ELCT564

  37. Energy and Power A source of electromagnetic energy sets up fields that store electric and magnetic energy and carry power that may be transmitted or dissipated as loss. The time-average stored electric energy in a volume V The time-average stored magnetic energy in a volume V ELCT564

  38. Energy and Power Poynting Vector (P0): power flow out of the closed surface S. Power Ps delivered by the sources Power dissipated in the volume due to conductivity, dielectric and magnetic losses (Pl) ELCT564

  39. Plane Wave Reflection from A Media Interface ELCT564

  40. Example Consider a plane wave normally incident on a half-space of copper. If f=1GHz, compute the propagation constant, intrinsic impedance, and skin depth for the conductor. Also compute the reflection and transmission coefficients (Copper’s conductivity is 5.813×107S/m). ELCT564

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