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Look at a distance z = - L toward the generator -z ZLZL ZcZc z = 0.

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Presentation on theme: "Look at a distance z = - L toward the generator -z ZLZL ZcZc z = 0."— Presentation transcript:

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3 Look at a distance z = - L toward the generator -z ZLZL ZcZc z = 0

4 -z ZLZL ZcZc z = 0

5 -z ZLZL ZcZc z = 0

6 -z ZLZL Z c1 z = 0 Z c2

7 -z ZLZL ZcZc z = 0

8 X = Z c tan kL L

9 Should I add something in series or in parallel?

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11 Eureka! Use a stub. -z ZLZL ZcZc z = 0 -z ZLZL ZcZc z = 0 -z ZLZL ZcZc z = 0

12 -z ZLZL ZcZc z = 0

13 -z ZLZL ZcZc z = 0  2 1.5 1

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15 -z ZLZL ZcZc z = 0 Not matched! -z ZLZL ZcZc z = 0 Needs some -jB somewhere, but where? -z ZLZL ZcZc z = 0 Eureka! Use a stub, somewhere. How long should it be?

16 An article appeared in the January, 1939 issue of Electronics that changed forever the way radio engineers think about transmission lines. Phil Smith [1907-1985] devised an extraordinarily clever circular chart that revealed graphically the complex impedance anywhere along a line. No math and minimum fuss. There's a marvelous symmetry in its design - everything fits together neatly. So ingenious was his invention that it has been the standard of the industry - for over sixty years.

17 -z ZLZL ZcZc z = 0

18 -z ZLZL ZcZc z = 0

19 -z ZLZL ZcZc z = 0

20 -z ZLZL ZcZc z = 0

21 -z ZLZL ZcZc z = 0

22 a x b y r Equation of circle (x - a) 2 + (y - b) 2 = r 2

23 clf; clear; plot([-1 1], [0 0], ’y’) axis equal axis off hold on

24 for r = [0.2.5 1 2 5] rr = 1 / (r + 1); cr = 1 - rr; tr = 2 * pi * (0 :.01: 1); plot(cr + rr * cos (tr), rr * sin (tr), ‘y’); end

25 RrRr RiRi R r = 1

26 for x = [.2.5 1 2 5] rx = 1 / x; cx = rx; tx = 2 * pi * (0 :.01: 1); plot(1 - rx * sin (tx), cx - rx * cos (tx), ‘y’); plot(1 - rx * sin (tx),- cx + rx * cos (tx), ‘y’); end

27 RrRr RiRi R r = 1

28 for x = [.2.5 1 2 5] rx = 1 / x; cx = rx; tx = 2 * atan(x) * (0 :.01: 1); plot(1 - rx * sin (tx), cx - rx * cos (tx), ‘y’); plot(1 - rx * sin (tx),- cx + rx * cos (tx), ‘y’); end

29 RrRr RiRi R r = 1

30 RrRr RiRi

31 To load To generator

32 |R| 1 0

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36 Movie to illustrate the frequency dependence of the impedance of a series resonant circuit

37 Movie to illustrate the frequency dependence of the impedance of a parallel resonant circuit

38 Movie to illustrate the transformation of a load impedance at various locations on the transmission line  

39 Movie to illustrate the transformation of an impedance to an admittance

40 y =  z = 0

41 Z c = 50  Z in = ? 

42 z = j1 z = 0

43 Z c = 50  Z in = ? 

44 0.434 Z c = 100  Z in = ?

45 z L = 2.6 + j1.8 z = 0.7 + j1.2

46 0.434 Z c = 100  Z in = ?

47 Single stub matching

48 y L = 2 + j1 y = 1 - j1 y = 1 + j1

49 y L =  y = - j1 y = + j1

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