GROL Test Equipment and Measurements 2

Question 1

What is the input impedance of most RF test instruments and transmission systems?

Accepted Answer

50 ohms

Answer

The standard impedance for most RF test equipment and coaxial transmission systems is 50 ohms, chosen as a compromise between power handling and low loss.

Question 2

What does noise figure (NF) measure in a receiver?

Accepted Answer

The degradation of signal-to-noise ratio caused by the receiver itself

Answer

Noise figure quantifies how much the signal-to-noise ratio degrades as a signal passes through the receiver, with lower NF indicating better sensitivity.

Question 3

What is the decibel (dB) expression for a power ratio of 2:1?

Accepted Answer

3 dB

Answer

A power ratio of 2:1 corresponds to approximately 3 dB because 10 × log₁₀(2) ≈ 3.01 dB.

Question 4

When using a vector network analyzer (VNA), what is S11 (return loss) a measure of?

Accepted Answer

Power reflected back from the device input (impedance mismatch)

Answer

S11 measures the ratio of reflected to incident power at the input port, indicating how well the device's input impedance matches the reference impedance.

Question 5

What is intermodulation distortion (IMD) in a receiver or amplifier?

Accepted Answer

Unwanted signals produced when two or more signals mix in a non-linear stage

Answer

IMD occurs when two or more signals interact in a non-linear device, producing spurious signals at sum and difference frequencies (and their harmonics).

(GROL) General Radiotelephone Operator License Practice Test

(GROL) General Radiotelephone Operator License Practice Test

GROL Test Equipment and Measurements 2