 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!
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RF Cafe Quizzes.
Note: Some material based on books have quoted passages.
Return to RF Cafe Quiz #43
 This
quiz is based on the information presented in Plasma Antennas, by Theodore Anderson.
Note: Some of these books are available as prizes in the monthly
RF Cafe Giveaway.
1. When the frequency of operation of a plasma antenna decreases, what is the corresponding
requirement for plasma density? c) Plasma density must decrease A rule of thumb is that the plasma
frequency should be about twice or greater than the operating frequency of the plasma antenna consider the plasma
antenna to behave as an effective metal antenna. (see page 4) 2. How does plasma
density affect signal phase during reflection and/or refraction? c) Plasma density affected by both
reflection and refraction This property allows flat panel plasma tube arrays to be programmed as scanning
phased arrays, adaptive parabolic, or just about any other shape antenna. (see page 5)
3. How is characteristic impedance controlled in a plasma antenna? d) All the above
The text specifically cites the plasma density's role in affecting impedance, but the plasma antenna's shape and
plasma material also determines impedance. (see page 34) 4. What commonly
available component is useful as a plasma antenna demonstrator? a) Fluorescent bulb
Probably the most useful fluorescent bulbs are the ones with a U shape that have electrode ends which can be
placed inside a metal enclosure with only the glass tube exposed as an antenna. (see page 38)
5. What is plasma, by the way? b) An ionized gas Duh. (see page 45)
6. In a multiple frequency nested plasma antenna, where is the highest frequency
antenna element located relative to the lowest frequency antenna element? b) Lowest frequency element on
the outside, highest frequency element on the inside Placing the denser, higher frequency at the innermost
location and layering outward with progressively lower densities with correspondingly lower frequencies allows the
inner layers to see through the outer layers (see page 47) 7. What is plasma
"windowing?"
a) Creating electronically switched portal regions around an antenna array Plasma regions can be made
transparent or opaque to the radiating (or receiving) antenna inside the enclosure in order to shape the field
beam. (see page 54) 8. What is a "smart" plasma antenna?
d) An antenna that use adaptive techniques to control beam patterns Computer control can be used to
determine angle of arrival, timestamp, and characterize signals, as well as do beam forming to target specific
intended recipients. (see page 79) 9. How can plasma materials be used to
provide filtering? b) Layering regions of plasmas allows specific frequencies to be selected and others
rejected Each frequency-selective (FSS) layer has to be modeled using numerical methods and layers are
stacked in such a way to create the desired filtering. (see page 113) 10. Who is
undoubtedly the master of using commercial fluorescent tubes for constructing plasma devices like antennas,
filters, and switches? a) Theodore Anderson Hands down. No question about it. (see entire book
Plasma Antennas) |
