Ham Radio General Class Test Ham Radio General Class Test Antennas and Feed Lines Questions and Answers 2

Question 1

What is the primary advantage of using open-wire (ladder line) feed line instead of coaxial cable?

Accepted Answer

Much lower loss at high SWR

Answer

Open-wire feed line has significantly lower loss than coax when operated at high SWR, making it ideal for multi-band antenna systems.

Question 2

What is the approximate length of a half-wave dipole antenna for 14.2 MHz?

Accepted Answer

33 feet

Answer

A half-wave dipole length is calculated as 468 divided by frequency in MHz, so 468/14.2 equals approximately 33 feet.

Question 3

Which type of antenna provides horizontal polarization when mounted parallel to the earth's surface?

Accepted Answer

A dipole

Answer

A dipole antenna mounted horizontally radiates a horizontally polarized signal.

Question 4

What does a balun do when used at the feed point of a dipole antenna?

Accepted Answer

Converts between balanced and unbalanced systems

Answer

A balun converts between the balanced feed point of a dipole and the unbalanced coaxial feed line, reducing common-mode currents.

Question 5

What is the feed point impedance of a quarter-wave ground-plane antenna with the radials bent downward at 45 degrees?

Accepted Answer

About 50 ohms

Answer

Bending the radials of a ground-plane antenna downward to 45 degrees raises the feed point impedance to approximately 50 ohms, providing a good match to common coaxial cable.

Ham Radio General Class Test Practice Test

Ham Radio General Class Test Practice Test

Ham Radio General Class Test Ham Radio General Class Test Antennas and Feed Lines Questions and Answers 2