E9A01
Which of the following describes an isotropic Antenna?
A. A grounded antenna used to measure earth conductivity
B. A horizontal antenna used to compare Yagi antennas
C. A theoretical antenna used as a reference for antenna gain
D. A spacecraft antenna used to direct signals toward the earth
E9A02
How much gain does a 1/2-wavelength dipole have compared to an isotropic antenna?
A. 1.55 dB
B. 2.15 dB
C. 3.05 dB
D. 4.30 dB
E9A03
Which of the following antennas has no gain in any direction?
A. Quarter-wave vertical
B. Yagi
C. Half-wave dipole
D. Isotropic antenna
E9A04
Why would one need to know the feed point impedance of an antenna?
A. To match impedances for maximum power transfer from a feed line
B. To measure the near-field radiation density from a transmitting antenna
C. To calculate the front-to-side ratio of the antenna
D. To calculate the front-to-back ratio of the antenna
E9A05
Which of the following factors determine the radiation resistance of an antenna?
A. Transmission-line length and antenna height
B. Antenna height and conductor length/diameter ratio, and location of nearby conductive objects
C. It is a physical constant and is the same for all antennas
D. Sunspot activity and time of day
E9A06
What is the term for the ratio of the radiation resistance of an antenna to the total resistance of the system?
A. Effective radiated power
B. Radiation conversion loss
C. Antenna efficiency
D. Beamwidth
E9A07
What is included in the total resistance of an antenna system?
A. Radiation resistance plus space impedance
B. Radiation resistance plus transmission resistance
C. Transmission-line resistance plus radiation resistance
D. Radiation resistance plus ohmic resistance
E9A08
What is a folded dipole antenna?
A. A dipole one-quarter wavelength long
B. A type of ground-plane antenna
C. A dipole constructed from one wavelength of wire forming a very thin loop
D. A hypothetical antenna used in theoretical discussions to replace the radiation resistance
E9A09
What is meant by antenna gain?
A. The numerical ratio relating the radiated signal strength of an antenna in the direction of maximum radiation to that of a reference antenna
B. The numerical ratio of the signal in the forward direction to that in the opposite direction
C. The ratio of the amount of power radiated by an antenna compared to the transmitter output power
D. The final amplifier gain minus the transmission-line losses (including any phasing lines present)
E9A10
What is meant by antenna bandwidth?
A. Antenna length divided by the number of elements
B. The frequency range over which an antenna satisfies a performance requirement
C. The angle between the half-power radiation points
D. The angle formed between two imaginary lines drawn through the element ends
E9A11
How is antenna efficiency calculated?
A. (radiation resistance / transmission resistance) x 100%
B. (radiation resistance / total resistance) x 100%
C. (total resistance / radiation resistance) x 100%
D. (effective radiated power / transmitter output) x 100%
E9A12
How can the efficiency of an HF quarter-wave grounded vertical antenna be improved?
A. By installing a good radial system
B. By isolating the coax shield from ground
C. By shortening the vertical
D. By reducing the diameter of the radiating element
E9A13(
Which is the most important factor that determines ground losses for a ground-mounted vertical antenna operating in the 3-30 MHz range?
A. The standing-wave ratio
B. Base current
C. Soil conductivity
D. Base impedance
E9A14
How much gain does an antenna have over a 1/2-wavelength dipole when it has 6 dB gain over an isotropic antenna?
A. 3.85 dB
B. 6.0 dB
C. 8.15 dB
D. 2.79 dB
E9A15
How much gain does an antenna have over a 1/2-wavelength dipole when it has 12 dB gain over an isotropic antenna?
A. 6.17 dB
B. 9.85 dB
C. 12.5 dB
D. 14.15 dB
E9A16
What is meant by the radiation resistance of an antenna?
A. The combined losses of the antenna elements and feed line
B. The specific impedance of the antenna
C. The value of a resistance that would dissipate the same amount of power as that radiated from an antenna
D. The resistance in the atmosphere that an antenna must overcome to be able to radiate a signal
E9B Antenna patterns: E and H plane patterns; gain as a function of pattern; antenna design (computer modeling of antennas)
; Yagi antennas
E9B01
What determines the free-space polarization of an antenna?
A. The orientation of its magnetic field (H Field)
B. The orientation of its free-space characteristic impedance
C. The orientation of its electric field (E Field)
D. Its elevation pattern
|
E9B02 In the antenna radiation pattern shown in Figure E9-1, what is the 3-dB beamwidth? A. 75 degrees B. 50 degrees C. 25 degrees D. 30 degrees
|
|
|
E9B03 In the antenna radiation pattern shown in Figure E9-1, what is the front-to-back ratio? A. 36 dB B. 18 dB C. 24 dB D. 14 dB
|
|
E9B04 In the antenna radiation pattern shown in Figure E9-1, what is the front-to-side ratio? A. 12 dB B. 14 dB C. 18 dB D. 24 dB
|
E9B05
What may occur when a directional antenna is operated at different frequencies within the band for which it was designed?
A. Feed-point impedance may become negative
B. The E-field and H-field patterns may reverse
C. Element spacing limits could be exceeded
D. The gain may exhibit significant variations
E9B06
What usually occurs if a Yagi antenna is designed solely for maximum forward gain?
A. The front-to-back ratio increases
B. The front-to-back ratio decreases
C. The frequency response is widened over the whole frequency band
D. The SWR is reduced
E9B07
If the boom of a Yagi antenna is lengthened and the elements are properly retuned, what usually occurs?
A. The gain increases
B. The SWR decreases
C. The front-to-back ratio increases
D. The gain bandwidth decreases rapidly
E9B08
How does the total amount of radiation emitted by a directional (gain) antenna compare with the total amount of radiation emitted from an isotropic antenna, assuming each is driven by the same amount of power?
A. The total amount of radiation from the directional antenna is increased by the gain of the antenna
B. The total amount of radiation from the directional antenna is stronger by its front to back ratio
C. There is no difference between the two antennas
D. The radiation from the isotropic antenna is 2.15 dB stronger than that from the directional antenna
E9B09
How can the approximate beamwidth of a directional antenna be determined?
A. Note the two points where the signal strength of the antenna is 3 dB less than maximum and compute the angular difference
B. Measure the ratio of the signal strengths of the radiated power lobes from the front and rear of the antenna
C. Draw two imaginary lines through the ends of the elements and measure the angle between the lines
D. Measure the ratio of the signal strengths of the radiated power lobes from the front and side of the antenna
E9B10
What type of computer program technique is commonly used for modeling antennas?
A. Graphical analysis
B. Method of Moments
C. Mutual impedance analysis
D. Calculus differentiation with respect to physical properties
E9B11
What is the principle of a Method of Moments analysis?
A. A wire is modeled as a series of segments, each having a distinct value of current
B. A wire is modeled as a single sine-wave current generator
C. A wire is modeled as a series of points, each having a distinct location in space
D. A wire is modeled as a series of segments, each having a distinct value of voltage across it
E9B12
What is a disadvantage of decreasing the number of wire segments in an antenna model below the guideline of 10 segments per half-wavelength?
A. Ground conductivity will not be accurately modeled
B. The resulting design will favor radiation of harmonic energy
C. The computed feed-point impedance may be incorrect
D. The antenna will become mechanically unstable
E9B13
Which of the following is a disadvantage of NEC-based antenna modeling programs?
A. They can only be used for simple wire antennas
B. They are not capable of generating both vertical and horizontal polarization patterns
C. Computing time increases as the number of wire segments is increased
D. All of these answers are correct
E9B14
What does the abbreviation NEC stand for when applied to antenna modeling programs?
A. Next Element Comparison
B. Numerical Electromagnetics Code
C. National Electrical Code
D. Numeric Electrical Computation
E9B15
What type of information can be obtained by submitting the details of a proposed new antenna to a modeling program?
A. SWR vs. frequency charts
B. Polar plots of the far-field elevation and azimuth patterns
C. Antenna gain
D. All of these answers are correct
E9C Wire and phased vertical antennas: beverage antennas; terminated and resonant rhombic antennas; elevation above real ground; ground effects as related to polarization; take-off angles
E9C01
What is the radiation pattern of two 1/4-wavelength vertical antennas spaced 1/2-wavelength apart and fed 180 degrees out of phase?
A. A cardioid
B. Omnidirectional
C. A figure-8 broadside to the axis of the array
D. A figure-8 oriented along the axis of the array
E9C02
What is the radiation pattern of two 1/4-wavelength vertical antennas spaced 1/4-wavelength apart and fed 90 degrees out of phase?
A. A cardioid
B. A figure-8 end-fire along the axis of the array
C. A figure-8 broadside to the axis of the array
D. Omnidirectional
E9C03
What is the radiation pattern of two 1/4-wavelength vertical antennas spaced 1/2-wavelength apart and fed in phase?
A. Omnidirectional
B. A cardioid
C. A Figure-8 broadside to the axis of the array
D. A Figure-8 end-fire along the axis of the array
E9C04
Which of the following describes a basic rhombic antenna?
A. Unidirectional; four-sided, each side one quarter-wavelength long; terminated in a resistance equal to its characteristic impedance
B. Bidirectional; four-sided, each side one or more wavelengths long; open at the end opposite the transmission line connection
C. Four-sided; an LC network at each corner except for the transmission connection;
D. Four-sided, each side of a different physical length
E9C05
What are the main advantages of a terminated rhombic antenna?
A. Wide frequency range, high gain and high front-to-back ratio
B. High front-to-back ratio, compact size and high gain
C. Unidirectional radiation pattern, high gain and compact size
D. Bidirectional radiation pattern, high gain and wide frequency range
E9C06
What are the disadvantages of a terminated rhombic antenna for the HF bands?
A. The antenna has a very narrow operating bandwidth
B. The antenna produces a circularly polarized signal
C. The antenna requires a large physical area and 4 separate supports
D. The antenna is more sensitive to man-made static than any other type
E9C07
What is the effect of a terminating resistor on a rhombic antenna?
A. It reflects the standing waves on the antenna elements back to the transmitter
B. It changes the radiation pattern from bidirectional to unidirectional
C. It changes the radiation pattern from horizontal to vertical polarization
D. It decreases the ground loss
|
E9C08 What type of antenna pattern over real ground is shown in Figure E9-2? A. Elevation B. Azimuth C. Radiation resistance D. Polarization | |
|
E9C09 What is the elevation angle of peak response in the antenna radiation pattern shown in Figure E9-2? A. 45 degrees B. 75 degrees C. 7.5 degrees D. 25 degrees
|
|
|
E9C10 What is the front-to-back ratio of the radiation pattern shown in Figure E9-2? A. 15 dB B. 28 dB C. 3 dB D. 24 dB
| |
|
E9C11 How many elevation lobes appear in the forward direction of the antenna radiation pattern shown in Figure E9-2? A. 4 B. 3 C. 1 D. 7
|
E9C12
How is the far-field elevation pattern of a vertically polarized antenna affected by being mounted over seawater versus rocky ground?
A. The low-angle radiation decreases
B. The high-angle radiation increases
C. Both the high- and low-angle radiation decrease
D. The low-angle radiation increases
E9C13
When constructing a Beverage antenna, which of the following factors should be included in the design to achieve good performance at the desired frequency?
A. Its overall length must not exceed 1/4 wavelength
B. It must be mounted more than 1 wavelength above ground
C. It should be configured as a four-sided loop
D. It should be one or more wavelengths long
E9C14
How would the electric field be oriented for a Yagi with three elements mounted parallel to the ground?
A. Vertically
B. Horizontally
C. Right-hand elliptically
D. Left-hand elliptically
E9C15
What strongly affects the shape of the far-field, low-angle elevation pattern of a vertically polarized antenna?
A. The conductivity and dielectric constant of the soil in the area of the antenna
B. The radiation resistance of the antenna and matching network
C. The SWR on the transmission line
D. The transmitter output power
***** E9C16 This question has been removed by the QPC
E9C17
What is the main effect of placing a vertical antenna over an imperfect ground?
A. It causes increased SWR
B. It changes the impedance angle of the matching network
C. It reduces low-angle radiation
D. It reduces losses in the radiating portion of the antenna
E9D Directional antennas: gain; satellite antennas; antenna beamwidth; losses; SWR bandwidth; antenna efficiency; shortened and mobile antennas; grounding
E9D01
How does the gain of a parabolic dish antenna change when the operating frequency is doubled?
A. Gain does not change
B. Gain is multiplied by 0.707
C. Gain increases 6 dB
D. Gain increases 3 dB
E9D02
What is one way to produce circular polarization when using linearly polarized antennas?
A. Stack two Yagis, fed 90 degrees out of phase, to form an array with the respective elements in parallel planes
B. Stack two Yagis, fed in phase, to form an array with the respective elements in parallel planes
C. Arrange two Yagis perpendicular to each other with the driven elements at the same point on the boom and fed 90 degrees out of phase
D. Arrange two Yagis collinear to each other, with the driven elements fed 180 degrees out of phase
E9D03
How does the beamwidth of an antenna vary as the gain is increased?
A. It increases geometrically
B. It increases arithmetically
C. It is essentially unaffected
D. It decreases
E9D04
Why is it desirable for a ground-mounted satellite communications antenna system to be able to move in both azimuth and elevation?
A. In order to track the satellite as it orbits the earth
B. So the antenna can be pointed away from interfering signals
C. So the antenna can be positioned to cancel the effects of Faraday rotation
D. To rotate antenna polarization to match that of the satellite
E9D05
For a shortened vertical antenna, where should a loading coil be placed to minimize losses and produce the most effective performance?
A. Near the center of the vertical radiator
B. As low as possible on the vertical radiator
C. As close to the transmitter as possible
D. At a voltage node
E9D06
Why should an HF mobile antenna loading coil have a high ratio of reactance to resistance?
A. To swamp out harmonics
B. To maximize losses
C. To minimize losses
D. To minimize the Q
E9D07
What is a disadvantage of using a multiband trapped antenna?
A. It might radiate harmonics
B. It can only be used for single-band operation
C. It is too sharply directional at lower frequencies
D. It must be neutralized
E9D08
What happens to the bandwidth of an antenna as it is shortened through the use of loading coils?
A. It is increased
B. It is decreased
C. No change occurs
D. It becomes flat
E9D09
What is an advantage of using top loading in a shortened HF vertical antenna?
A. Lower Q
B. Greater structural strength
C. Higher losses
D. Improved radiation efficiency
E9D10
What is the approximate feed-point impedance at the center of a folded dipole antenna?
A. 300 ohms
B. 72 ohms
C. 50 ohms
D. 450 ohms
E9D11
Why is a loading coil often used with an HF mobile antenna?
A. To improve reception
B. To lower the losses
C. To lower the Q
D. To cancel capacitive reactance
E9D12
What is an advantage of using a trapped antenna?
A. It has high directivity in the higher-frequency bands
B. It has high gain
C. It minimizes harmonic radiation
D. It may be used for multi-band operation
E9D13
What happens at the base feed-point of a fixed-length HF mobile antenna as the frequency of operation is lowered?
A. The resistance decreases and the capacitive reactance decreases
B. The resistance decreases and the capacitive reactance increases
C. The resistance increases and the capacitive reactance decreases
D. The resistance increases and the capacitive reactance increases
E9D14
Which of the following types of conductor would be best for minimizing losses in a station's RF ground system?
A. A resistive wire, such as a spark-plug wire
B. A thin, flat copper strap several inches wide
C. A cable with 6 or 7 18-gauge conductors in parallel
D. A single 12 or 10 gauge stainless steel wire
E9D15
Which of these choices would provide the best RF ground for your station?
A. A 50-ohm resistor connected to ground
B. A connection to a metal water pipe
C. A connection to 3 or 4 interconnected ground rods driven into the Earth
D. A connection to 3 or 4 interconnected ground rods via a series RF choke
E9E Matching: matching antennas to feed lines; power dividers
E9E01
What system matches a high-impedance transmission line to a lower impedance antenna by connecting the line to the driven element in two places spaced a fraction of a wavelength each side of element center?
A. The gamma matching system
B. The delta matching system
C. The omega matching system
D. The stub matching system
E9E02
What is the name of an antenna matching system that matches an unbalanced feed line to an antenna by feeding the driven element both at the center of the element and at a fraction of a wavelength to one side of center?
A. The gamma match
B. The delta match
C. The omega match
D. The stub match
E9E03
What is the name of the matching system that uses a short perpendicular section of transmission line connected to the feed line near the antenna?
A. The gamma match
B. The delta match
C. The omega match
D. The stub match
E9E04
What is the purpose of the series capacitor in a gamma-type antenna matching network?
A. To provide DC isolation between the feed-line and the antenna
B. To compensate for the inductive reactance of the matching network
C. To provide a rejection notch to prevent the radiation of harmonics
D. To transform the antenna impedance to a higher value
E9E05
How must the driven element in a 3-element Yagi be tuned to use a hairpin matching system?
A. The driven element reactance must be capacitive
B. The driven element reactance must be inductive
C. The driven element resonance must be lower than the operating frequency
D. The driven element radiation resistance must be higher than the characteristic impedance of the transmission line
E9E06
What is the equivalent lumped-constant network for a hairpin matching system on a 3-element Yagi?
A. Pi network
B. Pi-L network
C. L network
D. Parallel-resonant tank
E9E07
What parameter best describes the interactions at the load end of a mismatched transmission line?
A. Characteristic impedance
B. Reflection coefficient
C. Velocity factor
D. Dielectric Constant
E9E08
Which of the following measurements describes a mismatched transmission line?
A. An SWR less than 1:1
B. A reflection coefficient greater than 1
C. A dielectric constant greater than 1
D. An SWR greater than 1:1
E9E09
Which of these matching systems is an effective method of connecting a 50-ohm coaxial cable feed-line to a grounded tower so it can be used as a vertical antenna?
A. Double-bazooka match
B. Hairpin match
C. Gamma match
D. All of these answers are correct
E9E10
Which of these choices is an effective way to match an antenna with a 100-ohm terminal impedance to a 50-ohm coaxial cable feed-line?
A. Connect a 1/4-wavelength open stub of 300-ohm twin-lead in parallel with the coaxial feed-line where it connects to the antenna
B. Insert a 1/2 wavelength piece of 300-ohm twin-lead in series between the antenna terminals and the 50-ohm feed cable
C. Insert a 1/4-wavelength piece of 75-ohm coaxial cable transmission line in series between the antenna terminals and the 50-ohm feed cable
D. Connect 1/2 wavelength shorted stub of 75-ohm cable in parallel with the 50-ohm cable where it attaches to the antenna
E9E11
What is an effective way of matching a feed-line to a VHF or UHF antenna when the impedances of both the antenna and feed-line are unknown?
A. Use a 50-ohm 1:1 balun between the antenna and feed-line
B. Use the "universal stub" matching technique
C. Connect a series-resonant LC network across the antenna feed terminals
D. Connect a parallel-resonant LC network across the antenna feed terminals
E9E12
What is the primary purpose of a "phasing line" when used with an antenna having multiple driven elements?
A. It ensures that each driven element operates in concert with the others to create the desired antenna pattern
B. It prevents reflected power from traveling back down the feed-line and causing harmonic radiation from the transmitter
C. It allows single-band antennas to operate on other bands
D. It makes sure the antenna has a low-angle radiation pattern
E9E13
What is the purpose of a "Wilkinson divider"?
A. It divides the operating frequency of a transmitter signal so it can be used on a lower frequency band
B. It is used to feed high-impedance antennas from a low-impedance source
C. It divides power equally among multiple loads while preventing changes in one load from disturbing power flow to the others
D. It is used to feed low-impedance loads from a high-impedance source
E9F Transmission lines: characteristics of open and shorted feed
lines: 1/8 wavelength; 1/4 wavelength; 1/2 wavelength; feed lines:
coax versus open-wire; velocity factor; electrical length;
transformation characteristics of line terminated in impedance not
equal to characteristic impedance
E9F01
What is the velocity factor of a transmission line?
A. The ratio of the characteristic impedance of the line to the terminating impedance
B. The index of shielding for coaxial cable
C. The velocity of the wave in the transmission line multiplied by the velocity of light in a vacuum
D. The velocity of the wave in the transmission line divided by the velocity of light in a vacuum
E9F02
What determines the velocity factor in a transmission line?
A. The termination impedance
B. The line length
C. Dielectric materials used in the line
D. The center conductor resistivity
E9F03
Why is the physical length of a coaxial cable transmission line shorter than its electrical length?
A. Skin effect is less pronounced in the coaxial cable
B. The characteristic impedance is higher in a parallel feed line
C. The surge impedance is higher in a parallel feed line
D. Electrical signals move more slowly in a coaxial cable than in air
E9F04
What is the typical velocity factor for a coaxial cable with solid polyethylene dielectric?
A. 2.70
B. 0.66
C. 0.30
D. 0.10
E9F05 (was E9E10)
What is the physical length of a coaxial transmission line that is electrically one-quarter wavelength long at 14.1 MHz? (Assume a velocity factor of 0.66.)
A. 20 meters
B. 2.3 meters
C. 3.5 meters
D. 0.2 meters
E9F06
What is the physical length of a parallel conductor feed line that is electrically one-half wavelength long at 14.10 MHz? (Assume a velocity factor of 0.95.)
A. 15 meters
B. 20 meters
C. 10 meters
D. 71 meters
E9F07
What characteristic will 450-ohm ladder line have at 50 MHz, as compared to 0.195-inch-diameter coaxial cable (such as RG-58)?
A. Lower loss
B. Higher SWR
C. Smaller reflection coefficient
D. Lower velocity factor
E9F08
What is the term for the ratio of the actual speed at which a signal travels through a transmission line to the speed of light in a vacuum?
A. Velocity factor
B. Characteristic impedance
C. Surge impedance
D. Standing wave ratio
E9F09
What would be the physical length of a typical coaxial transmission line that is electrically one-quarter wavelength long at 7.2 MHz?
(Assume a velocity factor of 0.66)
A. 10 meters
B. 6.9 meters
C. 24 meters
D. 50 meters
E9F10
What kind of impedance does a 1/8-wavelength transmission line present to a generator when the line is shorted at the far end?
A. A capacitive reactance
B. The same as the characteristic impedance of the line
C. An inductive reactance
D. The same as the input impedance to the final generator stage
E9F11
What kind of impedance does a 1/8-wavelength transmission line present to a generator when the line is open at the far end?
A. The same as the characteristic impedance of the line
B. An inductive reactance
C. A capacitive reactance
D. The same as the input impedance of the final generator stage
E9F12
What kind of impedance does a 1/4-wavelength transmission line present to a generator when the line is open at the far end?
A. A very high impedance
B. A very low impedance
C. The same as the characteristic impedance of the line
D. The same as the input impedance to the final generator stage
E9F13
What kind of impedance does a 1/4-wavelength transmission line present to a generator when the line is shorted at the far end?
A. A very high impedance
B. A very low impedance
C. The same as the characteristic impedance of the transmission line
D. The same as the generator output impedance
E9F14
What kind of impedance does a 1/2-wavelength transmission line present to a generator when the line is shorted at the far end?
A. A very high impedance
B. A very low impedance
C. The same as the characteristic impedance of the line
D. The same as the output impedance of the generator
E9F15
What kind of impedance does a 1/2-wavelength transmission line present to a generator when the line is open at the far end?
A. A very high impedance
B. A very low impedance
C. The same as the characteristic impedance of the line
D. The same as the output impedance of the generator
E9F16
What is the primary difference between foam-dielectric coaxial cable as opposed to solid-dielectric cable, assuming all other parameters are the same?
A. Reduced safe operating voltage limits
B. Reduced losses per unit of length
C. Higher velocity factor
D. All of these answers are correct
E9G The Smith chart
E9G01
Which of the following can be calculated using a Smith chart?
A. Impedance along transmission lines
B. Radiation resistance
C. Antenna radiation pattern
D. Radio propagation
E9G02
What type of coordinate system is used in a Smith chart?
A. Voltage circles and current arcs
B. Resistance circles and reactance arcs
C. Voltage lines and current chords
D. Resistance lines and reactance chords
E9G03
Which of the following is often determined using a Smith chart?
A. Beam headings and radiation patterns
B. Satellite azimuth and elevation bearings
C. Impedance and SWR values in transmission lines
D. Trigonometric functions
E9G04
What are the two families of circles and arcs that make up a Smith chart?
A. Resistance and voltage
B. Reactance and voltage
C. Resistance and reactance
D. Voltage and impedance
|
E9G05 What type of chart is shown in Figure E9-3? A. Smith chart B. Free-space radiation directivity chart C. Elevation angle radiation pattern chart D. Azimuth angle radiation pattern chart
| ||
|
E9G06 On the Smith chart shown in Figure E9-3, what is the name for the large outer circle on which the reactance arcs terminate? A. Prime axis B. Reactance axis C. Impedance axis D. Polar axis
|
| |
|
E9G07 On the Smith chart shown in Figure E9-3, what is the only straight line shown? A. The reactance axis B. The current axis C. The voltage axis D. The resistance axis
|
E9G09
What third family of circles is often added to a Smith chart during the process of solving problems?
A. Standing-wave ratio circles
B. Antenna-length circles
C. Coaxial-length circles
D. Radiation-pattern circles
E9G10
What do the arcs on a Smith chart represent?
A. Frequency
B. SWR
C. Points with constant resistance
D. Points with constant reactance
E9G11
How are the wavelength scales on a Smith chart calibrated?
A. In fractions of transmission line electrical frequency
B. In fractions of transmission line electrical wavelength
C. In fractions of antenna electrical wavelength
D. In fractions of antenna electrical frequency
E9H Effective radiated power; system gains and losses; radio direction finding antennas
E9H01
What is the effective radiated power of a repeater station with 150 watts transmitter power output, 2-dB feed line loss, 2.2-dB duplexer loss and 7-dBd antenna gain?
A. 1977 watts
B. 78.7 watts
C. 420 watts
D. 286 watts
E9H02
What is the effective radiated power of a repeater station with 200 watts transmitter power output, 4-dB feed line loss, 3.2-dB duplexer loss, 0.8-dB circulator loss and 10-dBd antenna gain?
A. 317 watts
B. 2000 watts
C. 126 watts
D. 300 watts
E9H03
What is the effective radiated power of a repeater station with 200 watts transmitter power output, 2-dB feed line loss, 2.8-dB duplexer loss, 1.2-dB circulator loss and 7-dBd antenna gain?
A. 159 watts
B. 252 watts
C. 632 watts
D. 63.2 watts
E9H04
What term describes station output (including the transmitter, antenna and everything in between)
, when considering transmitter power and system gains and losses?
A. Power factor
B. Half-power bandwidth
C. Effective radiated power
D. Apparent power
E9H05
What is the main drawback of a wire-loop antenna for direction finding?
A. It has a bidirectional pattern
B. It is non-rotatable
C. It receives equally well in all directions
D. It is practical for use only on VHF bands
E9H06
What is the triangulation method of direction finding?
A. The geometric angle of sky waves from the source are used to determine its position
B. A fixed receiving station plots three headings from the signal source on a map
C. Antenna headings from several different receiving stations are used to locate the signal source
D. A fixed receiving station uses three different antennas to plot the location of the signal source
E9H07
Why is an RF attenuator desirable in a receiver used for direction finding?
A. It narrows the bandwidth of the received signal
B. It eliminates the effects of isotropic radiation
C. It reduces loss of received signals caused by antenna pattern nulls
D. It prevents receiver overload from extremely strong signals
E9H08
What is the function of a sense antenna?
A. It modifies the pattern of a DF antenna array to provide a null in one direction
B. It increases the sensitivity of a DF antenna array
C. It allows DF antennas to receive signals at different vertical angles
D. It provides diversity reception that cancels multipath signals
E9H09
What is a receiving loop antenna?
A. A large circularly-polarized antenna
B. A small coil of wire tightly wound around a toroidal ferrite core
C. One or more turns of wire wound in the shape of a large open coil
D. Any antenna coupled to a feed line through an inductive loop of wire
E9H10
How can the output voltage of a receiving loop antenna be increased?
A. By reducing the permeability of the loop shield
B. By increasing the number of wire turns in the loop and reducing the area of the loop structure
C. By reducing either the number of wire turns in the loop or the area of the loop structure
D. By increasing either the number of wire turns in the loop or the area of the loop structure
E9H11
Why is an antenna with a cardioid pattern desirable for a direction-finding system?
A. The broad-side responses of the cardioid pattern can be aimed at the desired station
B. The response characteristics of the cardioid pattern can assist in determining the direction of the desired station
C. The extra side lobes in the cardioid pattern can pinpoint the direction of the desired station
D. The high-radiation angle of the cardioid pattern is useful for short-distance direction finding
E9H12
What is an advantage of using a shielded loop antenna for direction finding?
A. It automatically cancels ignition noise pickup in mobile installations
B. It is electro-statically balanced against ground, giving better nulls
C. It eliminates tracking errors caused by strong out-of-band signals
D. It allows stations to communicate without giving away their position