CWS Antenna Theory & Types 1 — Questions and Answers
Question 1: What is the standard unit used to express antenna gain relative to an isotropic radiator?
- dBm
- dBi (Correct answer)
- dBd
- Watts
Correct answer: dBi
dBi (decibels relative to isotropic) expresses gain compared to a theoretical isotropic antenna that radiates equally in all directions.
Question 2: Which antenna type radiates power equally in all horizontal directions, making it ideal for general indoor WLAN coverage?
- Yagi-Uda antenna
- Parabolic dish antenna
- Omnidirectional dipole antenna (Correct answer)
- Patch panel antenna
Correct answer: Omnidirectional dipole antenna
An omnidirectional dipole antenna provides a 360-degree horizontal radiation pattern, making it well-suited for broad indoor WLAN coverage from a central location.
Question 3: What does the acronym EIRP stand for in the context of wireless networking?
- Effective Isotropic Radiated Power (Correct answer)
- Equivalent Interference Reduction Protocol
- Extended Internal Radio Performance
- Effective Integrated Radio Protocol
Correct answer: Effective Isotropic Radiated Power
EIRP (Effective Isotropic Radiated Power) represents the total power radiated by an antenna system, combining transmit power and antenna gain minus cable losses.
Question 4: What is the relationship between antenna gain and beamwidth?
- Higher gain produces a wider beamwidth
- Higher gain produces a narrower beamwidth (Correct answer)
- Gain and beamwidth are independent of each other
- Lower gain always produces a narrower beamwidth
Correct answer: Higher gain produces a narrower beamwidth
As antenna gain increases, the radiated energy is concentrated into a narrower beam, resulting in a smaller beamwidth in exchange for greater directional power.
Question 5: Which antenna type is most appropriate for a long-distance point-to-point outdoor wireless bridge?
- Omnidirectional rubber duck antenna
- Parabolic dish antenna (Correct answer)
- Indoor ceiling-mount patch antenna
- Whip antenna
Correct answer: Parabolic dish antenna
A parabolic dish antenna provides very high gain and an extremely narrow beamwidth, making it ideal for focusing signal energy over long point-to-point distances.
Question 6: What is antenna diversity in a WLAN system?
- Using antennas that operate on different frequency bands simultaneously
- Deploying antennas manufactured by different vendors in the same network
- Using multiple antennas and selecting the one receiving the strongest signal to improve reliability (Correct answer)
- Installing antennas on multiple floors of a building
Correct answer: Using multiple antennas and selecting the one receiving the strongest signal to improve reliability
Antenna diversity uses two or more antennas at a receiver and dynamically selects the antenna with the best signal, reducing the effects of multipath fading.
Question 7: What polarization orientation do most indoor WLAN access point antennas use by default?
- Horizontal polarization
- Circular polarization
- Vertical polarization (Correct answer)
- Cross polarization
Correct answer: Vertical polarization
Most indoor WLAN access point antennas use vertical polarization because the antennas are typically mounted upright and vertical polarization minimizes ground reflection losses.
CWS Antenna Theory & Types 1
What is the standard unit used to express antenna gain relative to an isotropic radiator?