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ECE 563 & TCOM 590 Microwave Engineering

ECE 563 & TCOM 590 Microwave Engineering. Planar Transmission Lines: Striplines and Microstrips October 14, 2004. Planar Transmission Lines. Parallel Plate Waveguide. Surface Waves on a Grounded Dielectric Slab.   0. x.   0  r. z. //////////////////////////////////////.

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ECE 563 & TCOM 590 Microwave Engineering

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  1. ECE 563 & TCOM 590Microwave Engineering Planar Transmission Lines: Striplines and Microstrips October 14, 2004

  2. Planar Transmission Lines

  3. Parallel Plate Waveguide

  4. Surface Waves on a Grounded Dielectric Slab 0 x 0r z //////////////////////////////////////

  5. Surface Waves on a Grounded Dielectric Slab

  6. Surface Waves on a Grounded Dielectric Slab – TM Mode

  7. Surface Waves on a Grounded Dielectric Slab – TM Mode

  8. TM mode cutoff frequencies

  9. Surface Waves on a Grounded Dielectric Slab – TE Modes

  10. TE mode cutoff frequencies

  11. Stripline Triplate transmission line

  12. Stripline Advantage (compared to parallel plates) • transverse fields remain in the vicinity of the center conductor between 2 grounded planes • 2 conductor line, no lower frequency cutoff: down to f=0 , up to cutoff of first TE mode. • Miniaturization

  13. Stripline • Compared to coax or waveguide • Advantage if Gunn diodes or mixer diodes to be apart of circuit design. • Advantage, large bandwidth, mini-size • Disadvantage- lack of isolation, lower power handling • Dominant mode - TEM

  14. Stripline

  15. Stripline

  16. Stripline

  17. Stripline

  18. Losses

  19. Attenuation due to conductor losses(approximate result)

  20. Planar Transmission Lines

  21. Microstrip Lines w t ////////// h ////////////////////// • Popular • fabricated by photolithographic processes • easily integrated with other passive and active microwave devices • convenient, economical; therefore, widespread use • Problem • radiation and undesired modes by lines at discontinuities

  22. Microstrip w t h

  23. Microstrip Design

  24. Microstrip Design Relationships

  25. Normalized Wavelength vs w/h

  26. Z0 and W/d approximation

  27. Effects to Dampen Signal Propagation along a Microstrip • Signal heats conductor through Ohmic Losses • Signal heats substrate which is not lossless • Signal leaks away as radiation

  28. Ohmic Losses

  29. Dielectric Losses

  30. Radiation Losses

  31. Radiation Losses

  32. Quality factor

  33. Microstrip-line Realization

  34. Microstrip-line Realization

  35. Microstrip Filter Design

  36. MicrostripLineCircuitElements

  37. Microwave Transmission

  38. Microwave Transmission Notes on striplines and microstrips • less bulky than waveguides • no need for welding and brazing • planar circuits - 2 dimensional universe • but high field concentration • limits power • breakdown • heating center condition • Open structure - radiates

  39. Microwave Advances • High Speed Circiuts • MMIC’s - Monolithic Integrated Circuits • High speed & high frequency • Photonics • Lightwave Techniques • fiber optics • image processing • high speed • Considerable Interaction • distribution of analog microwave signals via high speed fiber - optic links • optically controlled microwave devices & circuits

  40. Microwave Advances • Fiber-optic cables to route microwave signals • reduce size and weight • large bandwidth • immunity to interference • crosstalk isolation • potentially smaller transmission losses • applications • feeds for phased array antennas • delay lines, cable TV signal signal distribution

  41. Millimeter Wave Monolithic Integrated Circuits (MIMIC) • Affordable, reliable, reproducible wave and millimeter wave components • frequency • tests up to 40 GHz • pulse power goal S-band (3 GHz) to 75 GHz • Materials Research • GaAs • High electron mobility transistors (HEMT’s) • CAD • MHDL-Microwave Hardware Descriptive Language

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