Tektronix Telescope 1502C Manual de usuario descargar pdf (Pagina 108)

Appendix D: Application Note

D–2

1502C MTDR User Manual

Relationships

= (138 / pκ

(log

D / d) for coaxial cable

%= r

100

VSWR = (1 + r) + (1 – r) for the case where VSWR is the same for all

frequencies

c = 30 cm / nanosecond = 0.984 ft / ns

= 1 / pκ

= 30 / pκ cm / ns = 0.984 / pκ ft /ns

C = 7.36 κ + (log

D / d)

L = 140 log

D / d

1 in = 2.54 cm

1 ft = 30.48 cm

1 m = 3.28 ft

VSWR vs. Percent Reflected Voltage

To find the Voltage Standing Wave Ratio (VSWR), knowing the percent reflected

voltage (%), or vice versa, use the Frequency Domain Conversions section of the

slide rule (see Figure D–1).

0 2 4 6 8 1012141618 20 %

1.00 1.05 1.10 1.15 1.20 1.25 1.30 1.35 1.40 1.45 1.50 VWSR

80 75 70 65 60 55 50 45 40 35 30 25 20 15 10 5 0

.01 .02.03 .05 .10 .2 .3 .5 .7 1.0 2 3 5 7 10 20 50 100 %30

SINGLE

RESISTIVE

DISCONTINUITY

ONLY

RETURN LOSS

(IMPULSE ONLY)

1.04 VSWR = 2% REFLECTION 20% = 1.5 VSWR

Figure D–1: Slide Rule of VSWR vs. Percent Reflected Voltage

On the upper scale, locate the known value of VSWR (or %). Adjacent to that

point is the corresponding value for % (or VSWR). VSWR is the peak-to-valley

ratio of standing sine waves.

1 2 ... 103 104 105 106 107 108 109 110 111 112 113 ... 125 126

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Tektronix Telescope 1502C Manual de usuario Pagina 108