CWS CWS Basic RF Principles 4

Question 1

Which term describes the gain of an antenna compared to an isotropic radiator, expressed in dBi?

Accepted Answer

Antenna gain referenced to isotropic

Answer

dBi expresses antenna gain relative to a theoretical isotropic radiator that radiates equally in all directions.

Question 2

A higher-order modulation scheme like 256-QAM compared to 64-QAM requires:

Accepted Answer

A higher SNR to decode reliably

Answer

256-QAM encodes more bits per symbol but requires a cleaner, higher-SNR signal to distinguish the denser constellation points.

Question 3

What phenomenon occurs when an RF wave passes through the boundary between two media (e.g., air to glass) and changes direction?

Accepted Answer

Refraction

Answer

Refraction is the bending of an RF wave as it passes from one medium into another with a different refractive index.

Question 4

What does the term 'noise floor' represent in an RF system?

Accepted Answer

The minimum detectable signal level limited by thermal noise and receiver sensitivity

Answer

The noise floor is the level of background noise below which signals cannot be reliably detected by the receiver.

Question 5

MIMO technology improves wireless throughput primarily by:

Accepted Answer

Transmitting multiple independent data streams simultaneously using multiple antennas

Answer

MIMO uses multiple transmit and receive antennas to send parallel spatial streams, multiplying throughput without additional spectrum.

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