Ham Radio Technician Test Antennas & Feedlines 2

Question 1

What is the approximate length of a quarter-wave vertical antenna for the 2-meter band (146 MHz)?

Accepted Answer

19 inches

Answer

38 inches

Answer

9.5 inches

Answer

75 inches

Question 2

Which feedline type has the lowest loss per unit length at VHF frequencies?

Accepted Answer

Open-wire ladder line

Answer

Hardline (rigid coax)

Answer

RG-58

Answer

RG-8X

Question 3

What does a balun do in an antenna system?

Accepted Answer

It matches balanced to unbalanced transmission lines

Answer

It amplifies the signal before transmission

Answer

It filters harmonic frequencies

Answer

It measures antenna SWR

Question 4

What is the radiation pattern of a vertical quarter-wave antenna over a perfect ground plane?

Accepted Answer

Omnidirectional in the horizontal plane

Answer

Bidirectional like a figure-eight

Answer

Highly directional toward one end

Answer

Circular in the vertical plane only

Question 5

What is the effect of increasing coaxial cable diameter on signal loss?

Accepted Answer

Loss decreases

Answer

Loss increases

Answer

Loss is unaffected by diameter

Answer

Loss only changes above 1 GHz

Question 6

A 5/8-wave vertical antenna is often preferred over a quarter-wave vertical for VHF because it has:

Accepted Answer

A lower radiation angle and slight gain over a quarter-wave

Answer

Higher SWR that boosts power

Answer

A broader bandwidth

Answer

Less susceptibility to lightning

Question 7

What is the purpose of a ground plane on a vertical antenna?

Accepted Answer

It acts as the other half of the antenna and provides a return path for RF current

Answer

It shields the antenna from static buildup

Answer

It increases the antenna's resonant frequency

Answer

It prevents lightning from striking the antenna