Test Equipment and Measurements Flashcards
6 cards from real GROL practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Test Equipment and Measurements flashcards as text
What is the input impedance of most RF test instruments and transmission systems?
Answer: 50 ohms
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.
What does noise figure (NF) measure in a receiver?
Answer: The degradation of signal-to-noise ratio caused by the receiver itself
Noise figure quantifies how much the signal-to-noise ratio degrades as a signal passes through the receiver, with lower NF indicating better sensitivity.
What is the decibel (dB) expression for a power ratio of 2:1?
Answer: 3 dB
A power ratio of 2:1 corresponds to approximately 3 dB because 10 × log₁₀(2) ≈ 3.01 dB.
When using a vector network analyzer (VNA), what is S11 (return loss) a measure of?
Answer: Power reflected back from the device input (impedance mismatch)
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.
What is intermodulation distortion (IMD) in a receiver or amplifier?
Answer: Unwanted signals produced when two or more signals mix in a non-linear stage
IMD occurs when two or more signals interact in a non-linear device, producing spurious signals at sum and difference frequencies (and their harmonics).
What does a Bird-type directional wattmeter measure in a transmission line?
Answer: Forward (incident) and reflected power separately, allowing SWR calculation
A directional wattmeter (such as the Bird 43) uses a slug-and-meter system to measure forward power in one direction and reflected power in the other direction on the transmission line.