Mobile & Wireless Technology: RF Fundamentals

Questions and Answers

What does a higher gain in an antenna result in?

Increased electrical efficiency

Smaller coverage area

Greater coverage area (correct)

Lower output power

How is antenna gain usually expressed?

As a percentage of efficiency

In decibels relative to an isotropic radiator (dBi) (correct)

In milliWatts

In watts per meter

What factor affects the coverage area of an antenna apart from gain?

Physical size of the antenna

Polarization of the antenna (correct)

Type of metal used

Antenna color

What is the relationship between transmitter output power and signal coverage?

Higher output power increases signal coverage Signup and view all the answers

What does the capacity of a wireless access point refer to?

The number of users it can service effectively Signup and view all the answers

What defines Radio Frequency (RF)?

An electromagnetic wave used for transmitting information Signup and view all the answers

What does the term 'coverage' refer to in wireless LAN technology?

The geographical area reached by the signal Signup and view all the answers

Interference in wireless LANs can primarily be caused by which of the following?

Unexpected reflections of radio waves Signup and view all the answers

How are radio waves typically generated for wireless communications?

Using a high-frequency alternating current through an antenna Signup and view all the answers

What phenomenon allows radio waves to spread out as they pass through different materials?

Diffraction Signup and view all the answers

What does the term 'capacity' refer to in the context of a wireless LAN?

The number of connections a network can support Signup and view all the answers

Which effect occurs when radio waves encounter obstacles and are redirected?

Reflection Signup and view all the answers

What type of measurement unit is used to express the power of RF signals?

Decibels Signup and view all the answers

What is essential for successful wireless networking communication?

Clear, unobstructed line of sight Signup and view all the answers

What can significantly affect the RF line of sight?

Blockage of the Fresnel zone Signup and view all the answers

Which factors can cause blockage in an RF line of sight?

Curvature of the earth Signup and view all the answers

Which type of line of sight does RF communication require?

Both visual and RF line of sight Signup and view all the answers

What occurs when a receiver detects two different signals on similar frequencies?

Interference Signup and view all the answers

What is meant by an unobstructed line of sight in wireless communication?

Clear visibility without any obstacles Signup and view all the answers

What percentage blockage of the Fresnel zone can impact RF line of sight quality?

More than 40% Signup and view all the answers

Which of the following elements is NOT a common obstacle for RF signals?

Water vapor Signup and view all the answers

What does 0 dBm represent in terms of power?

1 milliwatt Signup and view all the answers

Which formula correctly converts milliwatts to dBm?

dBm = 10 × log10(Power mW) Signup and view all the answers

What does a dBm measurement of -30 dBm indicate?

Perfect signal strength Signup and view all the answers

What is the range of dBm values typically displayed for Wi-Fi signal strength?

-30 dBm to -90 dBm Signup and view all the answers

What factors influence how far an RF signal can travel?

Line of sight, interference, and environment Signup and view all the answers

Which of the following best describes RF communication requirements in wireless networking?

It requires a line of sight. Signup and view all the answers

In terms of signal strength, what does a measurement of -90 dBm signify?

Total disconnection Signup and view all the answers

Which type of line of sight is essential for RF communication?

Both visual and RF line of sight Signup and view all the answers

What is the primary purpose of an antenna in wireless communication?

To transform the signal into radio waves. Signup and view all the answers

Which frequency range does radio wave propagation typically cover?

3 kHz to 300 GHz Signup and view all the answers

Which of the following is NOT a communication method that utilizes RF waves?

Wired telephony Signup and view all the answers

What is one of the regulations governing RF spectrum in the USA?

FCC (47 CFR) Part 15C, Section 15.247 Signup and view all the answers

Which frequency bands does the IEEE 802.11 standard primarily address?

2.4 GHz ISM and 5 GHz UNII Signup and view all the answers

What aspect of wireless LAN does the term 'coverage' refer to?

The geographical area where the signal is accessible. Signup and view all the answers

Which is a key measurement unit in RF technology?

Decibel Signup and view all the answers

Which regulatory body is responsible for RF spectrum regulations in Malaysia?

Malaysian Communications and Multimedia Commission (MCMC) Signup and view all the answers

Study Notes

Key Terms in RF

Radio Frequency (RF): Electromagnetic waves used for communication.
Coverage: Area over which RF signals can be effectively transmitted.
Capacity: Maximum number of users an access point can serve efficiently.
Line of Sight: Direct visual and RF connection between transmitter and receiver.
Interference: Occurs when multiple signals overlap, causing distortion.
Reflection, Refraction, Diffraction, Scattering, Absorption: Various phenomena affecting RF wave propagation.

Structure of the Lesson

Focuses on RF fundamentals for Wireless LAN (WLAN) technology.
Covers frequencies, coverage and capacity, basic RF measurement units, and speed in RF communication.

Understanding Radio Frequency

RF is generated by high-frequency AC signals over copper cables, transforming into radio waves via antennas.
RF waves enable communication in various technologies including radio, television, cordless phones, WLANs, and satellite systems.
Frequency range for RF extends from 3 kHz to 300 GHz.

RF Regulation by Region

RF spectrum regulations are defined by respective local regulatory bodies:
- Malaysia: MCMC
- Canada: ISC RSS-210
- China: RRL/MIC Notice 2003-13
- Europe: ETSI standards (ETS 300.328, ETS 301.893)
- Israel: MOC
- Japan: TELEC ARIB STD-T71
- Singapore: IDA/TS SSS Issue 1
- Taiwan: PDT
- USA: FCC regulations (Part 15C, Sections 15.247 & 15.407)

Frequencies for Wireless LAN

IEEE 802.11 standard utilizes the 2.4 GHz ISM band and the 5 GHz UNII bands.
Antenna Gain: Measures efficiency of converting electric input to radio waves, expressed in dBi.
Higher antenna gain increases coverage area; lower gain results in smaller coverage area.
Antenna polarization (horizontal vs. vertical) influences radiation patterns and coverage.

Coverage and Capacity

WLAN hardware output power impacts signal coverage; higher power allows greater distance propagation.
Access point capacity limits the number of users it can effectively serve; expressed in dBm.
Calculation of dBm from milliwatts: dBm = 10 × log10(Power in mW).
Signal strength in Wi-Fi is measured from -30 dBm (ideal) to -90 dBm (disconnected).

RF Range and Speed

RF signal travel depends on factors like line of sight, environmental interference, and obstruction.
Two types of line of sight:
- Visual: Clear view between transmitter and receiver.
- RF: No more than 40% blockage of the Fresnel zone by obstacles (trees, buildings, terrain).
Interference can occur when a receiver detects multiple signals on similar frequencies, disrupting communication.

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Description

This quiz covers fundamental concepts of Radio Frequency (RF) essential for understanding Mobile and Wireless Technology. You will explore key terms such as coverage, capacity, interference, and propagation phenomena like reflection and diffraction. Mastering these terms is vital for success in assignments and exams related to this technology.