Extra Class License Exam Questions

Subelement E9

Antennas and Transmission Lines

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Group E9A Basic Antenna parameters: radiation resistance, gain, beamwidth, efficiency, beamwidth; effective radiated power, polarization
E9A01 What describes an isotropic antenna?
E9A02 What antenna has no gain in any direction?
E9A03 Why would one need to know the feed point impedance of an antenna?
E9A04 Which of the following factors may affect the feed point impedance of an antenna?
E9A05 What is included in the total resistance of an antenna system?
E9A06 How does the beamwidth of an antenna vary as the gain is increased?
E9A07 What is meant by antenna gain?
E9A08 What is meant by antenna bandwidth?
E9A09 How is antenna efficiency calculated?
E9A10 Which of the following choices is a way to improve the efficiency of a ground-mounted quarter-wave vertical antenna?
E9A11 Which of the following factors determines ground losses for a ground-mounted vertical antenna operating in the 3 MHz to 30 MHz range?
E9A12 How much gain does an antenna have compared to a 1/2-wavelength dipole when it has 6 dB gain over an isotropic antenna?
E9A13 How much gain does an antenna have compared to a 1/2-wavelength dipole when it has 12 dB gain over an isotropic antenna?
E9A14 What is meant by the radiation resistance of an antenna?
E9A15 What is the effective radiated power relative to a dipole 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?
E9A16 What is the effective radiated power relative to a dipole 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?
E9A17 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 dBi antenna gain?
E9A18 What term describes station output, taking into account all gains and losses?
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Group E9B Antenna patterns: E and H plane patterns; gain as a function of pattern; antenna design
E9B01 In the antenna radiation pattern shown in Figure E9-1, what is the 3 dB beam-width?
E9B02 In the antenna radiation pattern shown in Figure E9-1, what is the front-to-back ratio?
E9B03 In the antenna radiation pattern shown in Figure E9-1, what is the front-to-side ratio?
E9B04 What may occur when a directional antenna is operated at different frequencies within the band for which it was designed?
E9B05 What type of antenna pattern over real ground is shown in Figure E9-2?
E9B06 What is the elevation angle of peak response in the antenna radiation pattern shown in Figure E9-2?
E9B07 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?
E9B08 How can the approximate beam-width in a given plane of a directional antenna be determined?
E9B09 What type of computer program technique is commonly used for modeling antennas?
E9B10 What is the principle of a Method of Moments analysis?
E9B11 What is a disadvantage of decreasing the number of wire segments in an antenna model below the guideline of 10 segments per half-wavelength?
E9B12 What is the far field of an antenna?
E9B13 What does the abbreviation NEC stand for when applied to antenna modeling programs?
E9B14 What type of information can be obtained by submitting the details of a proposed new antenna to a modeling program?
E9B15 What is the front-to-back ratio of the radiation pattern shown in Figure E9-2?
E9B16 How many elevation lobes appear in the forward direction of the antenna radiation pattern shown in Figure E9-2?
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Group E9C Wire and phased array antennas: rhombic antennas; effects of ground reflections; e-off angles; Practical wire antennas: Zepps, OCFD, loops
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?
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?
E9C03 What is the radiation pattern of two 1/4 wavelength vertical antennas spaced a 1/2 wavelength apart and fed in phase?
E9C04 What happens to the radiation pattern of an unterminated long wire antenna as the wire length is increased?
E9C05 What is an OCFD antenna?
E9C06 What is the effect of a terminating resistor on a rhombic antenna?
E9C07 What is the approximate feed point impedance at the center of a two-wire folded dipole antenna?
E9C08 What is a folded dipole antenna?
E9C09 What is a G5RV antenna?
E9C10 Which of the following describes a Zepp antenna?
E9C11 How is the far-field elevation pattern of a vertically polarized antenna affected by being mounted over seawater versus rocky ground?
E9C12 Which of the following describes an extended double Zepp antenna?
E9C13 What is the main effect of placing a vertical antenna over an imperfect ground?
E9C14 How does the performance of a horizontally polarized antenna mounted on the side of a hill compare with the same antenna mounted on flat ground?
E9C15 How does the radiation pattern of a horizontally polarized 3-element beam antenna vary with its height above ground?
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Group E9D Directional antennas: gain; Yagi Antennas; losses; SWR bandwidth; antenna efficiency; shortened and mobile antennas; RF Grounding
E9D01 How does the gain of an ideal parabolic dish antenna change when the operating frequency is doubled?
E9D02 How can linearly polarized Yagi antennas be used to produce circular polarization?
E9D03 Where should a high Q loading coil be placed to minimize losses in a shortened vertical antenna?
E9D04 Why should an HF mobile antenna loading coil have a high ratio of reactance to resistance?
E9D05 What is a disadvantage of using a multiband trapped antenna?
E9D06 What happens to the bandwidth of an antenna as it is shortened through the use of loading coils?
E9D07 What is an advantage of using top loading in a shortened HF vertical antenna?
E9D08 What happens as the Q of an antenna increases?
E9D09 What is the function of a loading coil used as part of an HF mobile antenna?
E9D10 What happens to feed point impedance at the base of a fixed length HF mobile antenna as the frequency of operation is lowered?
E9D11 Which of the following types of conductors would be best for minimizing losses in a station's RF ground system?
E9D12 Which of the following would provide the best RF ground for your station?
E9D13 What usually occurs if a Yagi antenna is designed solely for maximum forward gain?
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Group E9E Matching: matching antennas to feed lines; phasing lines; power dividers
E9E01 What system matches a higher 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?
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?
E9E03 What is the name of the matching system that uses a section of transmission line connected in parallel with the feed line at or near the feed point?
E9E04 What is the purpose of the series capacitor in a gamma-type antenna matching network?
E9E05 How must the driven element in a 3-element Yagi be tuned to use a hairpin matching system?
E9E06 What is the equivalent lumped-constant network for a hairpin matching system of a 3-element Yagi?
E9E07 What term best describes the interactions at the load end of a mismatched transmission line?
E9E08 Which of the following measurements is characteristic of a mismatched transmission line?
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?
E9E10 Which of these choices is an effective way to match an antenna with a 100 ohm feed point impedance to a 50 ohm coaxial cable feed line?
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?
E9E12 What is the primary purpose of a phasing line when used with an antenna having multiple driven elements?
E9E13 What is a use for a Wilkinson divider?
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Group 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; coaxial cable dielectrics; velocity factor
E9F01 What is the velocity factor of a transmission line?
E9F02 Which of the following determines the velocity factor of a transmission line?
E9F03 Why is the physical length of a coaxial cable transmission line shorter than its electrical length?
E9F04 What is the typical velocity factor for a coaxial cable with solid polyethylene dielectric?
E9F05 What is the approximate physical length of a solid polyethylene dielectric coaxial transmission line that is electrically one-quarter wavelength long at 14.1 MHz?
E9F06 What is the approximate physical length of an air-insulated, parallel conductor transmission line that is electrically one-half wavelength long at 14.10 MHz?
E9F07 How does ladder line compare to small-diameter coaxial cable such as RG-58 at 50 MHz?
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?
E9F09 What is the approximate physical length of a solid polyethylene dielectric coaxial transmission line that is electrically one-quarter wavelength long at 7.2 MHz?
E9F10 What impedance does a 1/8 wavelength transmission line present to a generator when the line is shorted at the far end?
E9F11 What impedance does a 1/8 wavelength transmission line present to a generator when the line is open at the far end?
E9F12 What impedance does a 1/4 wavelength transmission line present to a generator when the line is open at the far end?
E9F13 What impedance does a 1/4 wavelength transmission line present to a generator when the line is shorted at the far end?
E9F14 What impedance does a 1/2 wavelength transmission line present to a generator when the line is shorted at the far end?
E9F15 What impedance does a 1/2 wavelength transmission line present to a generator when the line is open at the far end?
E9F16 Which of the following is a significant difference between foam dielectric coaxial cable and solid dielectric cable, assuming all other parameters are the same?
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Group E9G The Smith chart
E9G01 Which of the following can be calculated using a Smith chart?
E9G02 What type of coordinate system is used in a Smith chart?
E9G03 Which of the following is often determined using a Smith chart?
E9G04 What are the two families of circles and arcs that make up a Smith chart?
E9G05 What type of chart is shown in Figure E9-3?
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?
E9G07 On the Smith chart shown in Figure E9-3, what is the only straight line shown?
E9G08 What is the process of normalization with regard to a Smith chart?
E9G09 What third family of circles is often added to a Smith chart during the process of solving problems?
E9G10 What do the arcs on a Smith chart represent?
E9G11 How are the wavelength scales on a Smith chart calibrated?
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Group E9H Receiving Antennas: radio direction finding antennas; Beverage Antennas; specialized receiving antennas; longwire receiving antennas
E9H01 When constructing a Beverage antenna, which of the following factors should be included in the design to achieve good performance at the desired frequency?
E9H02 Which is generally true for low band (160 meter and 80 meter) receiving antennas?
E9H03 This question was deleted by the Question Pool Committee on February 1, 2016
E9H04 What is an advantage of using a shielded loop antenna for direction finding?
E9H05 What is the main drawback of a wire-loop antenna for direction finding?
E9H06 What is the triangulation method of direction finding?
E9H07 Why is it advisable to use an RF attenuator on a receiver being used for direction finding?
E9H08 What is the function of a sense antenna?
E9H09 Which of the following describes the construction of a receiving loop antenna?
E9H10 How can the output voltage of a multiple turn receiving loop antenna be increased?
E9H11 What characteristic of a cardioid pattern antenna is useful for direction finding?
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