RF Behavior & Signal Propagation Flashcards
7 cards from real CWS practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 RF Behavior & Signal Propagation flashcards as text
Which phenomenon causes a wireless signal to bend around corners or obstacles?
Answer: Diffraction
Diffraction allows RF signals to bend around the edges of obstacles, enabling coverage in areas not in direct line of sight.
What is the Fresnel zone primarily used to evaluate in wireless deployments?
Answer: Path clearance for line-of-sight links
Fresnel zones define elliptical regions around a line-of-sight path where obstructions can cause signal degradation due to phase cancellation.
Multipath propagation in an indoor environment most commonly results in which condition?
Answer: Signal fading and intersymbol interference
Multipath causes copies of the signal to arrive at different times, leading to fading and intersymbol interference that degrades throughput.
In free-space path loss calculations, doubling the distance between transmitter and receiver increases path loss by approximately how many dB?
Answer: 6 dB
Free-space path loss follows an inverse-square law, so doubling distance quadruples path loss, which is a 6 dB increase.
Which 802.11 technique was specifically designed to mitigate multipath-induced intersymbol interference?
Answer: OFDM guard interval (cyclic prefix)
The OFDM cyclic prefix (guard interval) absorbs multipath delay spread, preventing symbols from overlapping at the receiver.
When an RF signal passes from a less dense medium into a denser medium at an angle, it changes direction. This behavior is called:
Answer: Refraction
Refraction is the bending of an RF wave as it passes between media with different propagation velocities, such as air and glass.
A 5 GHz signal experiences greater free-space path loss than a 2.4 GHz signal at the same distance primarily because:
Answer: Higher frequency signals have shorter wavelengths and higher path loss per unit distance
Free-space path loss increases with frequency; 5 GHz signals have shorter wavelengths, resulting in higher path loss compared to 2.4 GHz at equal distances.