What combines to create the self-resonance of a component?
AnswerThe component’s nominal and parasitic reactance
A component self-resonates when its intended reactance interacts with an opposite-sign parasitic reactance.
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To what does the "4" in FT4 refer?
AnswerFour-tone continuous-phase frequency shift keying
The '4' in FT4 refers to its four-tone continuous-phase frequency-shift keying modulation.
How are impedances described in polar coordinates?
AnswerBy magnitude and phase angle
Polar impedance is described by a magnitude and a phase angle.
What is meant by the “mode” of an amateur radio satellite?
AnswerThe satellite’s uplink and downlink frequency bands
A satellite's operating mode identifies the frequency bands used for its uplink and downlink.
What is the maximum permitted transmitter output power when operating a model craft by telecommand?
Answer1 watt
The maximum transmitter output power for telecommand of a model craft is 1 watt.
What is the magnitude of the impedance of a series RLC circuit at resonance?
AnswerApproximately equal to circuit resistance
In a series RLC circuit at resonance, inductive and capacitive reactance cancel. The remaining impedance is approximately the circuit resistance.
What type of antenna pattern is shown in Figure E9-2?
AnswerElevation
Figure E9-2 plots antenna response as a function of elevation angle rather than compass direction.
At what time of day is transequatorial propagation most likely to occur?
AnswerAfternoon or early evening
Transequatorial propagation is most common in the afternoon and early evening, when equatorial ionization patterns favor the path.
Which of the following receiver circuits can be effective in eliminating interference from strong out-of-band signals?
AnswerA front-end filter or preselector
A front-end filter or preselector rejects strong signals before they reach sensitive receiver stages, making it effective against out-of-band overload.
What absolute voltage gain can be expected from the circuit in Figure E7-3 when R1 is 3,300 ohms and RF is 47 kilohms?
Answer14
The absolute inverting gain is RF/R1, giving about 14.
Which S parameter is equivalent to forward gain?
AnswerS21
S21 represents transmission from port 1 to port 2, which corresponds to forward gain in a two-port network.
Which of the following semiconductor materials contains excess free electrons?
AnswerN-type
N-type semiconductor material is doped so electrons are the majority carriers, giving it an excess of free electrons.
Which type of core material decreases inductance when inserted into a coil?
AnswerBrass
A brass core acts as a conductive, nonmagnetic slug that can reduce the inductance of a coil.
Which of the following can be measured by a two-port vector network analyzer?
AnswerFilter frequency response
A two-port VNA measures transmission through a network as frequency changes, so it can display a filter's amplitude and phase response.
How does an impedance-matching circuit transform a complex impedance to a resistive impedance?
AnswerIt cancels the reactive part of the impedance and changes the resistive part to the desired value
An impedance-matching network cancels the reactive component and transforms the remaining resistance to the desired value.
Over what range of frequencies are the FCC human body RF exposure limits most restrictive?
Answer30 - 300 MHz
The FCC human-body RF exposure limits are most restrictive from 30 to 300 MHz, where the body can absorb RF energy efficiently.
What undesirable effect can occur when using a noise blanker?
AnswerStrong signals may be distorted and appear to cause spurious emissions
A noise blanker driven too hard by strong signals can create distortion and spurious-looking products in the receiver.
What type of polarization is supported by ground-wave propagation?
AnswerVertical
Ground-wave propagation depends on the electric field interacting with Earth's surface, so vertical polarization is supported while horizontal polarization is heavily attenuated.
Which of the following is the likely result of using a Class C amplifier to amplify a single-sideband phone signal?
AnswerSignal distortion and excessive bandwidth
Class C is nonlinear and does not preserve the SSB amplitude envelope, producing distortion and unwanted spectral products.
Which of the following determines ground losses for a ground-mounted vertical antenna operating on HF?
AnswerSoil conductivity
The conductivity of the surrounding soil determines how much RF energy is lost in the ground system.
Why are received spread spectrum signals resistant to interference?
AnswerSignals not using the spread spectrum algorithm are suppressed in the receiver
A spread-spectrum receiver correlates for the expected spreading sequence, so unrelated signals are suppressed relative to the desired signal.
What frequencies are authorized to an amateur station operating under RACES rules?
AnswerAll amateur service frequencies authorized to the control operator
A RACES station may use any amateur-service frequency authorized to its control operator.
Which matching system for Yagi antennas requires the driven element to be insulated from the boom?
AnswerBeta or hairpin
A beta or hairpin match works with a driven element that must be insulated from the boom.
What is an effect of excessive phase noise in an SDR receiver’s master clock oscillator?
AnswerIt can combine with strong signals on nearby frequencies to generate interference
Master-clock phase noise in an SDR can mix with strong nearby signals and spread their energy into the desired channel, creating interference.