RF Cafe Software
About RF Cafe
1996 - 2016
BSEE - KB3UON
RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The Internet was still largely an unknown entity at the time and not much was available in the form of WYSIWYG ...
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All RF Cafe quizzes would make perfect 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.
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Note: Many answers contain passages quoted in whole or in part from the text.
This quiz is based on the information presented in Stimson's Introduction to Airborne Radar, Third Edition, by Hugh D. Griffiths, Christopher Baker, and David Adamy.
The publisher was not kidding when he stated, "recognizing that people who have an interest in airborne radars love airplanes, dispersed through the book are photos and renderings of radar-bearing aircraft from all over the world." If for no other reason, Stimson's book is a good one to leave on your desk or coffee table as a way-cool picture book for your friends to peruse while visiting. Introduction to Airborne Radar is in every sense a text designed to turn the electronics neophyte who has a reasonable grasp of algebra and physics into a technician who possesses a working knowledge of airborne radar (and radar in general) transmitter, receiver, antenna, and processor systems. The authors teach from first principles about antenna radiation, the decibel, frequency conversion, filtering, signal processing, target acquisition and tracking, spread spectrum, Doppler shift, radar cross section, electronic countermeasures, clutter cancelling, platform configurations, and much more. This book is not like the equally vaunted Skolnik Radar Handbook that is chock full of equations and theoretical discussions, known to make otherwise competent technophiles curl into a prenatal position while rocking back and forth. It is impossible for a reader to study this entire book and not be able to participate in an intelligent conversation on radar systems from both a technical standpoint and a historical perspective. Can you tell I'm impressed?
Note: Some of these books are available as prizes in the monthly RF Cafe Giveaway; however, this one will likely remain in my possession for a long time..
1. What is another, more common name for a coherent radar system?
a) Linear frequency radar
b) Linear phase radar
c) Pulse Doppler radar
d) Constant amplitude radar
2. Match the following common radar frequency bands with their central frequencies.
3. In which direction(s) does(do) an antenna's sidelobe(s) exist?
a) Front only
b) Side only
c) Back only
d) All directions
4. What causes a grating lobe in an electronically scanned antenna?
a) Spacing radiating elements at too great of a distance
b) Spacing radiating elements at too small of a distance
c) Too low radiated power
d) Too high radiated power
5. What is the main advantage of a pulsed radar over a non-pulsed radar?
a) Pulsed radar avoids transmitter leakage issues
b) Pulsed radar allows higher power
c) Pulsed radar is less expensive that non-pulsed radar
d) Pulsed radar can be used on airborne platforms whereas non-pulsed cannot
6. What is radar cross-section (RCS)?
a) Physical size of the radar unit
b) Physical size of the radar antenna
c) Effective size of the radar unit and antenna relative to a perfect radar system
d) Effective area of the signal reflecting surface relative to a perfectly reflecting sphere of the same projected area
7. What is "chirping?"
a) Linear amplitude modulation over the transmit time
b) Linear frequency modulation over the transmit time
c) Transmitting one under PAR
d) Radar return of a flock of birds
8. Coherence in radar refers to which of the following?
a) Time of the signal from one pulse to the next
b) Frequency of the signal from one pulse to the next
c) Amplitude of the signal from one pulse to the next
d) Phase of the signal from one pulse to the next
9. What defines bins in a Doppler filter bank?
a) Frequency bands
b) Amplitude ranges
c) Time segments
d) Phase angles
10. What is the name for unwanted returns from the ground?
c) Specular ambiguity
d) Frequency inversion
11. Match each picture with what it represents.
12. Which type of pulse repetition frequency (PRF) results in unambiguous range?
d) All three
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