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) No change — only frequency matters

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 unrelated

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