L2 Pre-flight

L2 Pre-flight#

Block 1: Radar Fundamentals — Lesson 2: EM Spectrum and Propagation Work this before L2. 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 wrap-up takeaways

  • The L2 Reading page in the course Jupyter Book, Spectrum & Propagation — radar bands, \(\lambda f = c\), free-space path loss and the 6 dB rules, polarization, and antenna gain.

Quiz questions (5 items, ~5 minutes)#

Q1. (Multiple choice) Which equation relates wavelength \(\lambda\) and frequency \(f\) for an EM wave in free space?

  • [ ] (a) \(\lambda + f = c\)

  • [ ] (b) \(\lambda f = c\)

  • [ ] (c) \(\lambda^2 f = c\)

  • [ ] (d) \(\lambda / f = c\)

Q2. (Multiple choice) A radar operating at 10 GHz has a wavelength of approximately:

  • [ ] (a) 3 m

  • [ ] (b) 30 cm

  • [ ] (c) 3 cm

  • [ ] (d) 3 mm

Q3. (Multiple choice) In free-space propagation, doubling the range \(R\) between transmitter and receiver changes the received power by:

  • [ ] (a) \(-3\) dB

  • [ ] (b) \(-6\) dB

  • [ ] (c) \(-12\) dB

  • [ ] (d) \(0\) dB

Q4. (Short answer) In one sentence, why does polarization matter in EW?

Q5. (Multiple choice) Which of the following best describes the relationship between antenna gain, aperture size, and beamwidth?

  • [ ] (a) More gain = larger aperture = wider beam

  • [ ] (b) More gain = smaller aperture = narrower beam

  • [ ] (c) More gain = larger aperture = narrower beam

  • [ ] (d) Gain and beamwidth are set independently

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