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.
Some of these books used in quizzes are available as prizes
in the monthly RF Cafe Giveaway.
Note: Many answers contain passages quoted in whole or in part from the text.
to RF Cafe Quiz #46
quiz is based on the information presented in Handbook of RF, Microwave, and
Millimeter-Wave Components, by Sergey M. Smolskiy, Leonid A. Belov, and Victor
What type of switch is shown to the right?
c) Transfer switch
A transfer switch in this case is a 2-position switch that allows simultaneous
signal re-routing between four ports. In this case either ports 1-4 and 2-3
are connected, or ports 1-2 and 3-4 are connected. Transfer switches are often
used in redundancy schemes.
(see page 214)
What is an adapto-attenuator?
a) Combination connector between-series
adaptor and an attenuator
Adapto-attenuators are simultaneously the
adapters; i.e., improve the section matching and the coupling the connectors
of different types, and provide the given attenuation value.
3. What do we call the difference
in decibels of the power output at a coupled port, when power is transmitted
in the desired direction, to the power output at the same coupled port when
power is transmitted in the opposite direction?
The difference in decibels of the power output at a coupled port, when
power is transmitted in the desired direction, to the power output at the
same coupled port when power is transmitted in the opposite direction.
(see page 116)
4. What is the main use
of a circulator?
d) To unidirectionally direct signals from one
port specifically to another
A circulator is a passive nonreciprocal
three- or four-port device, in which microwave or radio frequency power entering
any port is transmitted to the next port.
(see page 124)
5. What is a lumped element element filter?
b) A filter constructed of standard wire-wound inductors and parallel
A distributed element is constructed from a circuit board
trace having a specific width and length that exhibits an impedance equal
to a lumped element's impedance at the same frequency.
(see page 137)
6. What is a very desirable feature of
a YIG (yttrium-iron garnet) filter?
d) All the above
filters based on microwave YIG filters have the noticeable advantages: high
values of the Q-factor. opportunity of the electrical control by several octaves,
and high linearity of the medium frequency control. Bandpass filters can be
made to tune ranges as broad as 20:1 with few compromises in performance and
even larger ratios with trade-offs depending on actual frequency.
What does the image to the right represent?
b) 16-QAM constellation
Quadrature modulation uses in-phase and quadrature data streams to generate
a predictable combination of voltage-phase points that represent unique values.
In that case of 16-QAM, it allows 4 data bits to exchanged in a single clock
cycle, effectively multiplying the Baud rate so it is greater than the data
(see page 16)
8. In which
operational region of an amplifier is its1 dB compression point?
The 1 dB
compression point is the output power level where an input signal is amplified
by an amount that is 1 dB below its linear (normal) gain value. For instance,
if an amplifier had a linear gain of 20 dB when the input signal is 0 dBm,
then its output power would be +20 dB. If the amplifier with a linear gain
of 20 dB only produced an output of +19 dBm with a 0 dBm input signal, then
its 1 dB compression point would be +19 dBm since the gain is reduced by 1
dB at that power level, hence, it is nonlinear. Greater input power levels
will experience an even lower gain.
(see illustration on page 249)
What is an image rejection mixer?
a) A mixer that prevents the
image frequency from appearing at the output
For any LO (local oscillator)
frequency, there are two frequencies (RF input) that will mix with it to produce
the same output frequency (IF). One is the sum, and one is the difference.
The undesired of the two frequencies is the image frequency.
10. What are the main electrical
characteristics of a reference oscillator?
d) Center frequency,
stability, phase noise, harmonics, output power
As with most components,
various circuit and mechanical configurations and frequency determining elements
(crystal, YIG puck, cavity, etc.) are traded off to get the optimal performance
for the requirement.
(see page 357)