All RF Cafe quizzes make great fodder
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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RF Cafe Quizzes.
Note: Some material based on books have quoted passages.
This RF Electronics Basics quiz targets those of
you who are newcomers to the world of radio frequency (RF) electronics, but seasoned
vets are welcome to give it a go as well. Please report any suspected errors to me via
1. What comprises radio frequency signals?
a) A stream of photons.
b) Electromagnetic waves.
d) Beta rays (electrons).
2. How does an antenna achieve gain when it has no active signal
a) Excess electrons within the antenna structure increase the signal power.
b) Gain is achieved by directing (concentrating) a majority of the signal in a
preferred direction rather than equally in all direction.
c) By varying the
diameter of the radiating elements.
d) Antennas do not provide any sort of gain.
3. Why do RF people often speak of power in units of dBm and dBW
rather than milliwatts and watts, respectively?
a) They are equivalent and therefore are interchangable.
b) Using Latin
words makes them appear intelligent.
c) Scientific calculators and computer
algorithms handle dBm and dBW more efficiently.
d) Using dBm or dBW (decibels
relative to a milliwatt or watt, respectively) allows multiplication and division of
gains and losses to be performed as addition and subtraction, respectively.
4. Why do coaxial (coax) cables specify a minimum bend radius?
a) Too tight of a bend alters the internal physical dimension to where the impedance
change profoundly affects the internal signal.
b) To prevent breakage.
The outer insulation might split if the bend is too tight.
d) Coaxial cables
do not have a minimum bend radius.
5. Why do discrete components - resistors, capacitors, and inductors
- eventually not work as frequencies increase beyond some point?
a) Quantum mechanical tunneling dominates at high frequencies.
motion randomizes the electron "walk,' and thereby limits the frequency.
Parasitic resistance and reactance progressively dominates the component impedance as
the frequency increases.
d) There is no frequency dependence in discrete components.
6. What can cause a poorly shielded AM or FM radio to change its
audio level as you vary your distance from it?
a) Your body creates half of a capacitor (the radio and/or antenna is the other
half) that can alter the resonant frequency of the radio's local oscillator(s).
Your fingers act like windings an inductor and detune the circuit.
c) Your body
reflects the radio waves away from the radio.
d) Your natural aura is coupled
to the radio receiver circuitry.
7. What does the "S" in S-Parameters stand for?
8. What is the phase shift at the shorted end of a coaxial cable?
9. At what rate does the power of an RF signal attenuate in free
a) 2 dB for every doubling of distance.
b) 4 dB for every
doubling of distance.
c) 6 dB for every doubling of distance.
8 dB for every doubling of distance.
10. What is the name of the frequency band occupied by license-free
devices such as WiFi routers and Bluetooth headphones?
a) ISM (Industrial, Scientific, and Medical)
b) LF (License-Free)
c) USB (Unlicensed Side Band)
d) UHF (Unlicensed Hybrid Frequency)
Need some help? Click here for the
answers and explanations.
Posted February 7, 2018