Category: Feedlines - Matching and Antenna Systems
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Questions in this category:
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A-007-001-001: For an antenna tuner of the ""Transformer"" type, which of the following statements is FALSE?
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A-007-001-002: For an antenna tuner of the ""Series"" type, which of the following statements is false?
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A-007-001-003: For an antenna tuner of the ""L"" type, which of the following statements is false?
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A-007-001-004: For an antenna tuner of the ""Pi"" type, which of the following statements is false?
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A-007-001-005: What is a pi-network?
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A-007-001-006: Which type of network offers the greatest transformation ratio?
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A-007-001-007: Why is an L-network of limited utility in impedance matching?
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A-007-001-008: How does a network transform one impedance to another?
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A-007-001-009: What advantage does a pi-L network have over a pi-network for impedance matching between a vacuum tube linear amplifier and a multiband antenna?
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A-007-001-010: Which type of network provides the greatest harmonic suppression?
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A-007-001-011: A Smith Chart is useful:
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A-007-002-001: What kind of impedance does a quarter wavelength transmission line present to the source when the line is shorted at the far end?
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A-007-002-002: What kind of impedance does a quarter wavelength transmission line present to the source if the line is open at the far end?
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A-007-002-003: What kind of impedance does a half wavelength transmission line present to the source when the line is open at the far end?
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A-007-002-004: What kind of impedance does a half wavelength transmission line present to the source when the line is shorted at the far end?
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A-007-002-005: What is the velocity factor of a transmission line?
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A-007-002-006: What is the term for the ratio of the actual velocity at which a signal travels through a transmission line to the speed of light in a vacuum?
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A-007-002-007: What is a typical velocity factor for coaxial cable with polyethylene dielectric?
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A-007-002-008: What determines the velocity factor in a transmission line?
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A-007-002-009: Why is the physical length of a coaxial cable shorter than its electrical length?
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A-007-002-010: The reciprocal of the square root of the dielectric constant of the material used to separate the conductors in a transmission line gives the ____________ of the line:
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A-007-002-011: The velocity factor of a transmission line is the:
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A-007-003-001: What term describes a method used to match 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 on each side of the driven element centre?
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A-007-003-002: What term describes an unbalanced feed system in which the driven element of an antenna is fed both at the centre and a fraction of a wavelength to one side of centre?
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A-007-003-003: What term describes a method of antenna impedance matching that uses a short section of transmission line connected to the antenna transmission line near the antenna and perpendicular to the transmission line?
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A-007-003-004: Assuming a velocity factor of 0.66 what would be the physical length of a typical coaxial stub that is electrically one quarter wavelength long at 14.1 MHz?
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A-007-003-005: The driven element of a Yagi antenna is connected to a coaxial transmission line. The coax braid is connected to the centre of the driven element and the centre conductor is connected to a variable capacitor in series with an adjustable mechanical arrangement on one side of the driven element. The type of matching is:
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A-007-003-006: A quarter-wave stub, for use at 15 MHz, is made from a coaxial cable having a velocity factor of 0.8. Its physical length will be:
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A-007-003-007: The matching of a driven element with a single adjustable mechanical and capacitive arrangement is descriptive of:
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A-007-003-008: A Yagi antenna uses a gamma match. The coaxial braid connects to:
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A-007-003-009: A Yagi antenna uses a gamma match. The centre of the driven element connects to:
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A-007-003-010: A Yagi antenna uses a gamma match. The adjustable gamma rod connects to:
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A-007-003-011: A Yagi antenna uses a gamma match. The variable capacitor connects to the:
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A-007-004-001: In a half-wave dipole, the distribution of _______ is highest at each end.
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A-007-004-002: In a half-wave dipole, the distribution of _______ is lowest at each end.
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A-007-004-003: The feed point in a centre-fed half-wave antenna is at the point of:
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A-007-004-004: In a half-wave dipole, the lowest distribution of _________ occurs at the middle.
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A-007-004-005: In a half-wave dipole, the highest distribution of ________ occurs at the middle.
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A-007-004-006: A half-wave dipole antenna is normally fed at the point where:
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A-007-004-007: At the ends of a half-wave dipole:
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A-007-004-008: The impedance of a half-wave antenna at its centre is low, because at this point:
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A-007-004-009: In a half-wave dipole, where does minimum voltage occur?
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A-007-004-010: In a half-wave dipole, where does the minimum current occur?
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A-007-004-011: In a half-wave dipole, where does the minimum impedance occur?
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A-007-005-001: What is meant by circularly polarized electromagnetic waves?
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A-007-005-002: What type of polarization is produced by crossed dipoles fed 90 degrees out of phase?
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A-007-005-003: Which of these antennas does not produce circular polarization?
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A-007-005-004: On VHF/UHF frequencies, Doppler shift becomes of consequence on which type of communication?
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A-007-005-005: For VHF and UHF signals over a fixed path, what extra loss can be expected when linearly-polarized antennas are crossed-polarized (90 degrees)?
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A-007-005-006: Which of the following is NOT a valid parabolic dish illumination arrangement?
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A-007-005-007: A parabolic antenna is very efficient because:
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A-007-005-008: A helical-beam antenna with right-hand polarization will best receive signals with:
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A-007-005-009: One antenna which will respond simultaneously to vertically- and horizontally-polarized signals is the:
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A-007-005-010: In amateur work, what is the surface error upper limit you should try not to exceed on a parabolic reflector?
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A-007-005-011: You want to convert a surplus parabolic dish for amateur radio use, the gain of this antenna depends on:
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A-007-006-001: A transmitter has an output of 100 watts. The cable and connectors have a composite loss of 3 dB, and the antenna has a gain of 6 dBd. What is the Effective Radiated Power?
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A-007-006-002: As standing wave ratio rises, so does the loss in the transmission line. This is caused by:
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A-007-006-003: What is the Effective Radiated Power of an amateur transmitter, if the transmitter output power is 200 watts, the transmission line loss is 5 watts, and the antenna power gain is 3 dBd?
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A-007-006-004: Effective Radiated Power means the:
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A-007-006-005: A transmitter has an output power of 200 watts. The coaxial and connector losses are 3 dB in total, and the antenna gain is 9 dBd. What is the approximate Effective Radiated Power of this system?
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A-007-006-006: A transmitter has a power output of 100 watts. There is a loss of 1.30 dB in the transmission line, a loss of 0.2 dB through the antenna tuner, and a gain of 4.50 dBd in the antenna. The Effective Radiated Power (ERP) is:
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A-007-006-007: If the overall gain of an amateur station is increased by 3 dB the ERP (Effective Radiated Power) will:
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A-007-006-008: A transmitter has a power output of 125 watts. There is a loss of 0.8 dB in the transmission line, 0.2 dB in the antenna tuner, and a gain of 10 dBd in the antenna. The Effective Radiated Power (ERP) is:
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A-007-006-009: If a 3 dBd gain antenna is replaced with a 9 dBd gain antenna, with no other changes, the Effective Radiated Power (ERP) will increase by:
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A-007-006-010: A transmitter has an output of 2000 watts PEP. The transmission line, connectors and antenna tuner have a composite loss of 1 dB, and the gain from the stacked Yagi antenna is 10 dBd. What is the Effective Radiated Power (ERP) in watts PEP?
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A-007-006-011: A transmitter has an output of 1000 watts PEP. The coaxial cable, connectors and antenna tuner have a composite loss of 1 dB, and the antenna gain is 10 dBd. What is the Effective Radiated Power (ERP) in watts PEP?
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A-007-007-001: For a 3-element Yagi antenna with horizontally mounted elements, how does the main lobe takeoff angle vary with height above flat ground?
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A-007-007-002: Most simple horizontally polarized antennas do not exhibit significant directivity unless they are:
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A-007-007-003: The plane from which ground reflections can be considered to take place, or the effective ground plane for an antenna is:
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A-007-007-004: Why is a ground-mounted vertical quarter-wave antenna in reasonably open surroundings better for long distance contacts than a half-wave dipole at a quarter wavelength above ground?
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A-007-007-005: When a half-wave dipole antenna is installed one-half wavelength above ground, the:
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A-007-007-006: How does antenna height affect the horizontal (azimuthal) radiation pattern of a horizontal dipole HF antenna?
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A-007-007-007: For long distance propagation, the vertical radiation angle of the energy from the antenna should be:
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A-007-007-008: Greater distance can be covered with multiple-hop transmissions by decreasing the:
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A-007-007-009: The impedance at the centre of a dipole antenna more than 3 wavelengths above ground would be nearest to:
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A-007-007-010: Why can a horizontal antenna closer to ground be advantageous for close range communications on lower HF bands?
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A-007-007-011: Which antenna system and operating frequency are most suitable for Near Vertical Incidence (NVIS) communications?
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A-007-008-001: What is meant by the radiation resistance of an antenna?
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A-007-008-002: Why would one need to know the radiation resistance of an antenna?
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A-007-008-003: What factors determine the radiation resistance of an antenna?
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A-007-008-004: What is the term for the ratio of the radiation resistance of an antenna to the total resistance of the system?
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A-007-008-005: What is included in the total resistance of an antenna system?
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A-007-008-006: How can the approximate beamwidth of a beam antenna be determined?
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A-007-008-007: How is antenna percent efficiency calculated?
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A-007-008-008: What is the term used for an equivalent resistance which would dissipate the same amount of energy as that radiated from an antenna?
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A-007-008-009: Antenna beamwidth is the angular distance between:
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A-007-008-010: If the ohmic resistance of a half-wave dipole is 2 ohms, and the radiation resistance is 72 ohms, what is the antenna efficiency?
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A-007-008-011: If the ohmic resistance of a miniloop antenna is 2 milliohms and the radiation resistance is 50 milliohms, what is the antenna efficiency?
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A-007-009-001: Waveguide is typically used:
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A-007-009-002: Which of the following is not correct? Waveguide is an efficient transmission medium because it features:
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A-007-009-003: Which of the following is an advantage of waveguide as a transmission line?
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A-007-009-004: For rectangular waveguide to transfer energy, the cross-section should be at least:
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A-007-009-005: Which of the following statements about waveguide IS NOT correct?
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A-007-009-006: Which of the following is a major advantage of waveguide over coaxial cable for use at microwave frequencies?
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A-007-009-007: What is printed circuit transmission line called?
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A-007-009-008: Compared with coaxial cable, microstripline:
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A-007-009-009: A section of waveguide:
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A-007-009-010: Stripline is a:
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A-007-009-011: What precautions should you take before beginning repairs on a microwave feed horn or waveguide?