Study Technician T9A

T9A

ANTENNAS AND FEED LINES

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

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T9A01

What is a beam antenna?

  1. A An antenna built from square aluminum beams
  2. B An omnidirectional antenna invented by Clarence Beam
  3. C An antenna that concentrates signals in one direction
  4. D An antenna that focuses the signal into two intense rays
T9A02

Which of the following describes a type of antenna loading?

  1. A Electrically lengthening by inserting inductors in radiating elements
  2. B Inserting a resistor in the radiating portion of the antenna to make it resonant
  3. C Installing a spring in the base of a mobile vertical antenna to make it more flexible
  4. D Strengthening the radiating elements of a beam antenna to better resist wind damage
T9A03

How is the polarization of an antenna described?

  1. A By the shape of the driven element
  2. B By the orientation of the electric field
  3. C By the orientation of the magnetic field
  4. D By the direction of radiation
T9A04

What is a disadvantage of a handheld radio transceiver's short flexible antenna compared to a full-sized quarter-wave antenna?

  1. A It has low efficiency
  2. B It transmits only circularly polarized signals
  3. C It is more susceptible to receiver desensitization
  4. D It only works on analog signals, not digital ones
T9A05

Which of the following increases the resonant frequency of a dipole antenna?

  1. A Lengthening it
  2. B Inserting coils in series with radiating wires
  3. C Shortening it
  4. D Adding capacitive loading to the ends of the radiating wires
T9A06

Which of the following types of antennas offers the greatest gain?

  1. A 5/8 wave vertical
  2. B Isotropic
  3. C J pole
  4. D Yagi
T9A07

What is a potential drawback of using a handheld VHF transceiver inside a vehicle that lacks an externally mounted antenna?

  1. A Signal strength is reduced due to the shielding effect of the vehicle
  2. B The bandwidth of the antenna will decrease, increasing SWR
  3. C The SWR might decrease, decreasing the signal strength
  4. D The handheld will overheat due to reflected power in the vehicle
T9A08

Why is a 19-inch-long vertical antenna often used on 2 meters?

  1. A It has high gain
  2. B It is a resonant half-wave
  3. C It is a resonant quarter-wave
  4. D It has low RF radiation exposure
T9A09

What is an advantage of a 5/8-wavelength whip antenna for VHF or UHF mobile service compared to a 1/4-wave antenna?

  1. A It has more gain
  2. B It radiates at a higher angle
  3. C It has lower SWR
  4. D It has lower impedance
T9A10

In which direction does a half-wave dipole antenna radiate the strongest signal?

  1. A Equally in all directions
  2. B Off the ends of the antenna
  3. C In the direction of the feed line
  4. D Broadside to the antenna
T9A11

What is antenna gain?

  1. A The additional power that is added to the transmitter power
  2. B The additional power that is required in the antenna when transmitting on a higher frequency
  3. C The increase in signal strength in a specified direction compared to a reference antenna
  4. D The increase in impedance on receive or transmit compared to a reference antenna
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