T9_Antennas_&_Feed_Lines

What is a beam antenna?

• An antenna built from aluminum I-beams
• . An omnidirectional antenna invented by Clarence Beam
• An antenna that concentrates signals in one direction
• An antenna that reverses the phase of received signals

Which of the following describes a type of antenna loading?

• Electrically lengthening by inserting inductors in radiating elements
• Inserting a resistor in the radiating portion of the antenna to make it resonant
• Installing a spring in the base of a mobile vertical antenna to make it more flexible
• Strengthening the radiating elements of a beam antenna to better resist wind damage

Which of the following describes a simple dipole oriented parallel to Earth's surface?

• A ground-wave antenna
• A horizontally polarized antenna
• A travelling-wave antenna
• A vertically polarized antenna

What is a disadvantage of the short, flexible antenna supplied with most handheld radio transceivers, compared to a full-sized quarter-wave antenna?

• It has low efficiency
• It transmits only circularly polarized signals
• It is mechanically fragile
• All these choices are correct

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

• Lengthening it
• Inserting coils in series with radiating wires
• Shortening it
• Adding capacitive loading to the ends of the radiating wires

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

• 5/8 wave vertical
• Isotropic
• J pole
• Yagi

What is a disadvantage of using a handheld VHF transceiver with a flexible antenna inside a vehicle?

• Signal strength is reduced due to the shielding effect of the vehicle
• The bandwidth of the antenna will decrease, increasing SWR
• The SWR might decrease, decreasing the signal strength
• All these choices are correct

What is the approximate length, in inches, of a quarter-wavelength vertical antenna for 146 MHz?

• 112
• 50
• 19
• 12

What is the approximate length, in inches, of a half-wavelength 6 meter dipole antenna?

• 6
• 50
• 112
• 236

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

• Equally in all directions
• Off the ends of the antenna
• In the direction of the feed line
• Broadside to the antenna