Unformatted text preview: 13.44 CHAPTER 13. TRANSMISSION LINES not peakto—peak) of voltage oscillations V(z, t) on the transmission line are measured
at each location on the transmission line during operation and plotted plotted in
Figure 13.44. a. What is the frequency of the voltage source in Hz? b. What is the magnitude 3 [I‘L of the loadreﬂection coef— g: 5 . ﬁcient? g
Q c. What is the phase of the 1‘ loadreﬂection coefﬁcient FL? 3 Give a numerical value in de— .2 grees. d. What is the magnitude I+] 1 _ . of the forward current wave on 32 _1‘1 4'0 411 .5 _.1', 45 5.; _1 _3 _2 1 u
the transmission line? Hauntmeters! e. What is the value of the load impedance Z L? Figure 13.44: Standingwave pattern along the transmission line of Figure 13.43. Problem 13.27: Sliding—probe measurements made on a Z, = 50 (2 transmission
line indicate a voltage standingwave ratio (VSWR) of 4, with a voltage minimum at
a distance of A/ 5 from the load. a. What is the magnitude of the reﬂection coefﬁcient ‘1‘]? b. What is the complex value of l" at a point at which the voltage is minimum? c. Show that the impedance on the line (VTotal/ITotal) at a point 3A/8 toward the
generator from the voltage minimum is 23.5 — 344.1 9. (1. At what distance from the voltage minimum should one insert a series—reactive
element in order to match the line? e. What value of reactance would be required? 1’. If, instead of the reactive element of part (c), a shorted stub of the same transmis
sion line is to be connected in parallel across the line for matching, Where should it
be connected and how long should it be? Problem 13.28: Consider a parallel—plate transmission line made of a real metal
with imperfect conductivity. Let the spacing between the plates be at and their width
be W. The air between the plates is lossless, but each plate has a resistance per unit
length of R3. Page 13.7 develops a general solution for lossy transmission lines. a. Write the telegrapher’s differential equations for this case of lossy conductors and
lossless dielectric. b. Write the phasor solutions for the voltage and current waves. c. Find the complex characteristic impedance, Z0, of the transmission line. Problem 13.29: A 250—9 load is connected to a sinusoidal voltage source via a ...
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 Fall '06
 RANA
 Electromagnet

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