L3 Pre-flight

L3 Pre-flight#

Block 1: Radar Fundamentals — Lesson 3: The Radar Range Equation Work this before L3. Pre-flights are never collected — in class, anyone may be cold-called to present any question at the board, and that recitation is the participation grade.

Assumed pre-class reading#

  • L1 and L2 wrap-ups

  • The Jupyter Book Reading page for L3, The Radar Range Equation — in particular two-way propagation, radar cross section as an effective area, and the \(R^{-4}\) dependence.

Quiz questions (5 items, ~5 minutes)#

Q1. (Multiple choice) In free space, the received power at a one-way receiver falls off as \(1/R^2\). In a monostatic radar engagement, what is the dependence of received power on range?

  • [ ] (a) \(1/R\)

  • [ ] (b) \(1/R^2\)

  • [ ] (c) \(1/R^3\)

  • [ ] (d) \(1/R^4\)

Q2. (Multiple choice) The radar cross section \(\sigma\) of a target has units of:

  • [ ] (a) Watts

  • [ ] (b) dB

  • [ ] (c) Square meters

  • [ ] (d) Meters per second

Q3. (Multiple choice) For a fixed radar (every other term constant), how does maximum detection range \(R_{\max}\) scale with target RCS \(\sigma\)?

  • [ ] (a) \(R_{\max} \propto \sigma\)

  • [ ] (b) \(R_{\max} \propto \sigma^{1/2}\)

  • [ ] (c) \(R_{\max} \propto \sigma^{1/4}\)

  • [ ] (d) \(R_{\max} \propto \sigma^{4}\)

Q4. (Short answer) In one sentence, explain why a 12 dB reduction in RCS only halves the radar’s detection range, instead of cutting it more dramatically.

Q5. (Multiple choice) Which one of the following parameters in the radar range equation is primarily controlled by the aircraft designer rather than the radar designer?

  • [ ] (a) Transmit power \(P_t\)

  • [ ] (b) Antenna gain \(G_t\)

  • [ ] (c) Wavelength \(\lambda\)

  • [ ] (d) Radar cross section \(\sigma\)

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