to RF Cafe Quiz #7
All RF Cafe Quizzes make great fodder for
employment interviews for technicians or engineers - particularly those who are
fresh out of school or are relatively new to the work world. Come to think of it,
they would make equally excellent study material for the same persons who are going
to be interviewed for a job. Bonne chance, Viel Glück, がんばろう,
buena suerte, удачи, in bocca al lupo, 행운을 빕니다,
ádh mór, בהצלחה, lykke til, 祝你好運.
Well, you know what I mean: Good luck!
Click here for the complete list of
RF Cafe Quizzes.
Note: Some material based on books have quoted passages.
1. What is a "radar mile?"
c) 12.36 µs
A radar mile is the time required for a signal leaving the antenna to go out
and back one nautical mile (6076 feet). 2 * 6076 ft / [9.8356e8 ft/s]
= 12.36 µs
2. Which best describes a bistatic radar?
a) Fixed transmitter and fixed receiver at different locations
Many bi-static systems use multiple receiving sites to be able to pick up weaker
reflected signals and to correlate position information with more certainty.
3. What is a radar cross-section (RCS)?
b) A target's reflecting capacity equivalent to a perfectly reflecting surface
of the same area
For radar evasion (stealth), a low RCS is desirable. To guarantee being detected
(general & commercial aviation, a high RCS is desirable. A B-52 bomber has an
RCS of about 100 m2 (20 dBsm, whereas an F-117 Stealth Fighter has about
a 0.003 m2 RCS (which at X-band puts it in the realm of birds).
4. What are common units of radar cross-section (RCS)?
Decibels relative to a square meter.
5. Who is known as "The Father of Radar?"
a) Robert Watson-Watt
Sir Robert Watson-Watt, with the help of his assistant Arnold Wilkins, drafted,
in February 1935, a report titled "The Detection of Aircraft by Radio Methods."
Walter Eugene O'Reilly was "Radar" from the television show M*A*S*H.
6. Which flying (movement) condition will always result in a
Doppler speed of 0 m/s?
b) Perfect concentric circle around antenna at constant altitude
Doppler speed is manifested on the boresight radial line (main radiation lobe)
so, neglecting "blind speeds," the only way to be moving and have the Doppler speed
at 0 m/s is to not have any motion relative to the boresight radial line.
7. What does "MTI" stand for?
c) Moving Target Indication
Moving Target Indication (MTI) uses a cancellation system that blanks out stationary
targets to permit only moving targets to be displayed on the display. Doing so greatly
reduces the clutter and allows relatively weak moving targets to be seen in the
midst of buildings, trees, etc.
8. Synthetic Aperture Radar (SAR) radar is mostly
likely to be located on which platform?
Synthetic Aperture Radar (SAR) relies on the motion of the platform to produce
the "scan" that would otherwise be provided by a rotating or steerable antenna.
9. Which feature of a "stealth" aircraft is most responsible for its low observability?
b) Multi-faceted surfaces
The angle of a signal's reflection form a surface is equal to the angle of its
incidence on the surface. By minimizing the area presented perpendicular to any
given direction (particularly those direction most likely to be illuminated, like
from below and the side), a minimum amount of incident radar signal energy will
be reflected back in the direction from which it originated (the radar).
10. What kind of radar did the webmaster of RF Cafe work on while in the U.S.A.F?
In the U.S. government system designation standard, the "M" stands for ground
Mobile, the "P" stands for Radar, and the "N" stands for Navigational aides. The
"-14" designates position in a series.
Related Pages on RF Cafe
Introduction to Radar (Air University)
- Radar Equation, 2-Way
Radar Equation, 1-Way
Radar Equation, Bistatic
Radar Techniques - Primer (1945 QST)
- RF Cafe Quiz #7 - Radar Principles
- AN/MPN-14 USAF Radar Shop
- AN/TPN-19 USAF Radar Shop
Handbook - Doppler Shift
- Doppler Shift Calculator
Identification Friend or Foe (IFF)
Radar Horizon / Line of Sight
- Radar Systems Vendors
NEETS Radar Principles
- Radar System Vendors
- Who Invented Radar?
Simple Modification Increases ATC Reliability
Posted October 11, 2019