Transmission Media Chapter 4 Quiz

Wireless Transmission Frequencies

• Frequencies range from 30 MHz to 40 GHz, divided into three categories: radio range (30 MHz), microwave frequencies (1 GHz - 40 GHz), and infrared portion of the spectrum.
• Radio range (30 MHz) is suitable for omnidirectional applications.
• Microwave frequencies (1 GHz - 40 GHz) are highly directional and suitable for point-to-point transmissions and satellite communications.
• Infrared portion of the spectrum is useful for local point-to-point and multipoint applications within confined areas.

Antennas

• Antennas are electrical conductors or systems of conductors used to radiate or collect electromagnetic energy.
• Radio frequency electrical energy from the transmitter is converted into electromagnetic energy by the antenna and radiated into the surrounding environment.
• Reception occurs when the electromagnetic signal intersects the antenna.

Types of Antennas

• Isotropic antenna: radiates power in all directions equally, with an actual radiation pattern resembling a sphere with the antenna at the center.
• Omnidirectional antenna: radiates most of its power in one plane (either vertical or horizontal), e.g., 360°.

Transmission Media

• Guided media: twisted pair, coaxial cable, and optical fiber.
• Unguided media: isotropic/parabolic antenna, terrestrial microwave, satellite microwave, and broadcast radio.

Data, Signal, Transmission

• Data: entities that include meaning or information, can be analog (continuous values) or digital (discrete values).
• Signal: an action, sound, or movement that conveys a message, information, or order; an electromagnetic or electrical current that carries data from one system or network to another.
• Transmission (or Signaling): physical propagation and processing of signals along a suitable medium.

Line Configuration

• Direct link: no intermediate devices other than amplifiers or repeaters are used to increase signal strength.
• Topology: physical arrangement of stations on medium, including point-to-point (P2P) and multi-point configurations.

Transmission Modes

• Simplex: signals are transmitted in only one direction, one station is transmitter and the other is receiver.
• Duplex:
• Half duplex: only one station may transmit at a time, requires one data path.
• Full duplex: simultaneous transmission and reception between two stations, requires two data paths.

Channel Capacity - Bandwidth and Data Rate

• Channel capacity is measured by bandwidth and data rate.
• Examples of channel bandwidth include AM radio (10 kHz), FM radio (200 kHz), and cellular/wifi frequencies (300 MHz - 30 GHz).