FCCライセンス 6月 3 2024 SUBELEMENT T9A SUBELEMENT T9A T9A – Antennas: vertical and horizontal polarization, concept of antenna gain, definition and types of beam antennas, antenna loading, common portable and mobile antennas, relationships between resonant length and frequency, dipole pattern 1 / 12 T9A01What is a beam antenna? A. An antenna built from aluminum I-beams B. An omnidirectional antenna invented by Clarence Beam C. An antenna that concentrates signals in one direction D. An antenna that reverses the phase of received signals 2 / 12 T9A02Which of the following describes a type of antenna loading? A. Electrically lengthening by inserting inductors in radiating elements B. Inserting a resistor in the radiating portion of the antenna to make it resonant C. Installing a spring in the base of a mobile vertical antenna to make it more flexible D. Strengthening the radiating elements of a beam antenna to better resist wind damage 3 / 12 T9A03Which of the following describes a simple dipole oriented parallel to Earth's surface? A. A ground-wave antenna B. A horizontally polarized antenna C. A travelling-wave antenna D. A vertically polarized antenna 4 / 12 T9A04What is a disadvantage of the short, flexible antenna supplied with most handheld radio transceivers, compared to a full-sized quarter-wave antenna? A. It has low efficiency B. It transmits only circularly polarized signals C. It is mechanically fragile D. All these choices are correct 5 / 12 T9A05Which of the following increases the resonant frequency of a dipole antenna? A. Lengthening it B. Inserting coils in series with radiating wires C. Shortening it D. Adding capacitive loading to the ends of the radiating wires 6 / 12 T9A06Which of the following types of antenna offers the greatest gain? A. 5/8 wave vertical B. Isotropic C. J pole D. Yagi 7 / 12 T9A07What is a disadvantage of using a handheld VHF transceiver with a flexible antenna inside a vehicle? A. Signal strength is reduced due to the shielding effect of the vehicle B. The bandwidth of the antenna will decrease, increasing SWR C. The SWR might decrease, decreasing the signal strength D. All these choices are correct 8 / 12 T9A08What is the approximate length, in inches, of a quarter-wavelength vertical antenna for 146 MHz? A. 112 B. 50 C. 19 D. 12 9 / 12 T9A09What is the approximate length, in inches, of a half-wavelength 6 meter dipole antenna? A. 6 B. 50 C. 112 D. 236 10 / 12 T9A10In which direction does a half-wave dipole antenna radiate the strongest signal? A. Equally in all directions B. Off the ends of the antenna C. In the direction of the feed line D. Broadside to the antenna 11 / 12 T9A11What is antenna gain? A. The additional power that is added to the transmitter power B. The additional power that is required in the antenna when transmitting on a higher frequency C. The increase in signal strength in a specified direction compared to a reference antenna D. The increase in impedance on receive or transmit compared to a reference antenna 12 / 12 T9A12What is an advantage of a 5/8 wavelength whip antenna for VHF or UHF mobile service? A. It has more gain than a 1/4-wavelength antenna B. It radiates at a very high angle C. It eliminates distortion caused by reflected signals D. It has 10 times the power gain of a 1/4 wavelength whip Your score isThe average score is 75% 0% Restart quiz Ed 1 コメント
75％