CWT CWT Antenna Systems & Site Surveys 2 — Questions and Answers
Question 1: What is the free-space path loss (FSPL) principle and how does it affect wireless network design?
- Loss caused only by physical obstructions like walls
- The natural attenuation of RF signals as they propagate through open air, increasing with distance and frequency (Correct answer)
- Signal loss due to antenna misalignment only
- Loss caused exclusively by multipath interference
Correct answer: The natural attenuation of RF signals as they propagate through open air, increasing with distance and frequency
Free-space path loss is the reduction in signal strength as an RF wave travels through open air, increasing with both distance and frequency.
Question 2: A directional Yagi antenna is BEST suited for which deployment scenario?
- Providing even coverage throughout a large open warehouse
- Creating a point-to-point outdoor wireless bridge between two buildings (Correct answer)
- Connecting multiple clients from a central indoor location
- Replacing omnidirectional antennas inside conference rooms
Correct answer: Creating a point-to-point outdoor wireless bridge between two buildings
Yagi antennas concentrate RF energy in a narrow beam, making them ideal for point-to-point links where maximizing gain in one direction is critical.
Question 3: What does the term 'beamwidth' describe in the context of antenna specifications?
- The physical width of the antenna element
- The cable thickness required for the antenna
- The angle in degrees between the half-power (-3 dB) points of an antenna's radiation pattern (Correct answer)
- The frequency bandwidth the antenna supports
Correct answer: The angle in degrees between the half-power (-3 dB) points of an antenna's radiation pattern
Beamwidth is the angular measurement between the -3 dB points of an antenna's radiation pattern, indicating how focused or broad the coverage area is.
Question 4: What is multipath propagation and what problem can it cause in wireless networks?
- Using multiple antennas to boost signal strength
- RF signals arriving at a receiver via multiple reflected paths, potentially causing interference or fading (Correct answer)
- A technique for transmitting on multiple frequencies simultaneously
- The use of multiple SSIDs on a single access point
Correct answer: RF signals arriving at a receiver via multiple reflected paths, potentially causing interference or fading
Multipath propagation occurs when reflected RF copies of a signal arrive at slightly different times, which can cause destructive interference and signal fading.
Question 5: Which tool is specifically designed to detect non-Wi-Fi interference sources such as microwave ovens and Bluetooth devices during a site survey?
- Wi-Fi analyzer app
- Spectrum analyzer (Correct answer)
- Protocol analyzer
- Cable tester
Correct answer: Spectrum analyzer
A spectrum analyzer sweeps across radio frequencies to display all RF energy, including non-Wi-Fi sources that protocol analyzers cannot detect.
Question 6: What is the Fresnel zone and why must it be considered for outdoor point-to-point links?
- The zone where encryption is applied to wireless signals
- A series of ellipsoidal regions around the line of sight that must be kept mostly clear to avoid signal diffraction and loss (Correct answer)
- The legal RF power limit zone set by the FCC
- The coverage radius around an omnidirectional antenna
Correct answer: A series of ellipsoidal regions around the line of sight that must be kept mostly clear to avoid signal diffraction and loss
The Fresnel zone is an ellipsoidal volume around the line-of-sight path; obstructions within this zone diffract RF energy and reduce link performance.
CWT CWT Antenna Systems & Site Surveys 2
What is the free-space path loss (FSPL) principle and how does it affect wireless network design?