1. ECE 563 & TCOM 590 Microwave 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r0r 00 x z //////////////////////////////////////

5. Surface Waves on a Grounded Dielectric Slab

6. 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

18. Losses

19. Attenuation due to conductor losses (approximate result)

20. Planar Transmission Lines

21. h ////////// t w ////////////////////// Microstrip Lines ­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

24. Microstrip w t h

25. Microstrip Design

26. Microstrip Design Relationships

27. Normalized Wavelength vs w/h

28. Z 0 and W/d approximation

29. 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

30. Ohmic Losses

31. Dielectric Losses

32. Radiation Losses

34. Quality factor

35. Microstrip-line Realization

37. Microstrip Filter Design

38. Microstrip Line Circuit Elements

39. Microwave Transmission

40. 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

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

42. 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

43. 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