Ham Radio Technician Test Antennas & Feedlines 3

Question 1

What is the impedance of a typical half-wave dipole antenna in free space?

Accepted Answer

73 ohms

Answer

A half-wave dipole in free space has a feed-point impedance of approximately 73 ohms.

Question 2

What happens to the SWR on a feedline if the antenna is perfectly matched to the line's characteristic impedance?

Accepted Answer

SWR equals 1:1

Answer

A perfect impedance match results in an SWR of 1:1, meaning all power is transferred to the antenna with no reflections.

Question 3

What is the main disadvantage of using a very long coaxial feedline run at UHF frequencies?

Accepted Answer

Significantly increased signal loss

Answer

Coaxial cable loss increases with frequency, so long runs at UHF can lose a substantial portion of your transmit power.

Question 4

Which type of antenna connector is most commonly used for handheld VHF/UHF transceivers?

Accepted Answer

SMA

Answer

SMA connectors are standard on most modern handheld (HT) transceivers due to their small size.

Question 5

What is the term for the ratio of the maximum to minimum voltage along a transmission line?

Accepted Answer

Voltage Standing Wave Ratio (VSWR)

Answer

Voltage Standing Wave Ratio (VSWR) specifically measures the ratio of maximum to minimum voltage amplitude along the feedline.

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