CBT RF Transmission & Antenna Systems

Question 1

What is the primary purpose of a transmission line in a broadcast RF system?

Accepted Answer

To transfer RF energy from the transmitter to the antenna with minimal loss

Answer

To amplify the RF signal before it reaches the antenna

Answer

To filter out unwanted harmonics in the transmitted signal

Answer

To match the antenna impedance to the studio equipment

Question 2

Which parameter describes the ratio of reflected wave voltage to incident wave voltage on a transmission line?

Accepted Answer

Voltage Reflection Coefficient (Γ)

Answer

Standing Wave Ratio (SWR)

Answer

Return Loss

Answer

Insertion Loss

Question 3

A broadcast FM antenna has a gain of 6 dBd. Approximately how many times greater is its effective radiated power compared to a dipole radiating the same transmitter power?

Accepted Answer

4 times

Answer

2 times

Answer

6 times

Answer

8 times

Question 4

What is the standard characteristic impedance of most coaxial transmission lines used in broadcast RF systems?

Accepted Answer

50 ohms

Answer

25 ohms

Answer

75 ohms

Answer

300 ohms

Question 5

What does VSWR of 1:1 indicate about a transmission line system?

Accepted Answer

The load is perfectly matched and no power is reflected

Answer

Maximum power is being reflected back to the transmitter

Answer

The line is completely open-circuited at the load

Answer

The system is operating at exactly half its rated power

Question 6

Which type of antenna is most commonly used for omnidirectional FM broadcast coverage?

Accepted Answer

Circularly polarized panel antenna or batwing antenna

Answer

Yagi-Uda antenna

Answer

Log-periodic antenna

Answer

Parabolic reflector antenna

Question 7

What is the purpose of an antenna diplexer in a broadcast facility?

Accepted Answer

To combine two transmitters operating on different frequencies onto a single antenna

Answer

To split one antenna feed into two separate transmission lines

Answer

To match the transmitter output impedance to 600 ohms

Answer

To filter AM harmonics from the FM transmission line