Section 6.1 · Further exercises · 12 of 17

Exercise 6.1.12: Speed and miss distance from a Doppler record

About the further exercises of Section 6.1

Seventeen further exercises in the spirit of the problems, the home exercises and the worked examples, graded from easy to harder within each group. Exercises 6.1.1–6.1.4 are about uniform plane waves, , , and the triad, Exercises 6.1.5–6.1.6 about power, energy and loss, Exercises 6.1.7–6.1.10 about polarisation, Exercises 6.1.11–6.1.12 about the Doppler effect, and Exercises 6.1.13–6.1.17 mix power, exposure and polarisation. Besides the relations listed at the head of this subsection they use the lossy forms , , and (Exercise 6.1.6 only), the average energy density , Faraday's law , and the polarisation match . A field factor is .

Exercise 6.1.12

Speed and miss distance from a Doppler record

#

A CW radar at watches an aircraft that flies straight and level at constant speed and passes the radar at the closest distance . The recorded Doppler shift starts near , falls through zero at the moment of closest approach with the slope and ends near . (a) With at closest approach, show that . (b) Find . (c) Find . (d) How long does take to fall from to of its far value?

Figure
Try it yourself first.

cf. Home exercise 6.1.6

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