Coaxial Cable | Guided Media | Transmission Medium | Computer Networks

Key Concepts

Coaxial cable, guided media, baseband transmission, broadband transmission, impedance, connectors (BNC, F-connector), thinnet, thicknet, advantages, disadvantages, attenuation, noise immunity, bandwidth.

Coaxial Cable: An Overview

The video discusses coaxial cables as a type of guided transmission medium. Guided media use a physical path for signal transmission, unlike unguided media (wireless). Coaxial cables are commonly used for cable TV, internet, and connecting satellite dishes.

Structure of a Coaxial Cable

1. Central Copper Wire (Inner Conductor): Carries the electrical signal.
2. Insulator (Dielectric): A layer of PVC insulation surrounding the central wire, preventing it from touching the outer layers.
3. Metal Shield (Outer Conductor): A woven mesh of copper or aluminum that acts as a ground and shields the inner conductor from external interference.
4. Outer Insulation (Jacket): A plastic covering (PVC) that protects the cable from physical damage and environmental factors.

Types of Coaxial Cables

• Thinnet (RG-58): Easier to install and more flexible.
• Thicknet (RG-11): Higher impedance, capable of longer distances and higher bandwidth.

Advantages of Coaxial Cables

1. High Bandwidth: Supports high data transfer rates, suitable for multiple channels and high-definition video.
2. Long Distance Transmission: Can transmit signals over longer distances compared to twisted pair cables.
3. Noise Immunity: The shielding protects the signal from external electromagnetic interference.
4. Relatively Inexpensive: Less expensive than fiber optic cables.

Disadvantages of Coaxial Cables

1. Attenuation: Signal strength weakens over long distances, requiring amplifiers or repeaters.
2. Susceptibility to Damage: Can be damaged if cut or improperly handled, leading to signal loss.
3. More Expensive than Twisted Pair: More costly than twisted pair cables, although less expensive than fiber optic cables.

Baseband vs. Broadband Transmission

• Baseband: Transmits a single signal at a time. Commonly used for digital transmission. Requires amplification at regular intervals. Used in LAN (Local Area Network).
• Broadband: Transmits multiple signals simultaneously using different frequencies. Used for analog transmission, such as cable TV.

Connectors

• BNC (Bayonet Neill-Concelman): Used for connecting coaxial cables to devices.
• F-Connector: Commonly used for connecting coaxial cables to TVs, satellite receivers, and cable modems.

Conclusion

Coaxial cables are a reliable and cost-effective solution for transmitting data and video signals. While they have some limitations, such as attenuation and susceptibility to damage, their high bandwidth, noise immunity, and relatively low cost make them a popular choice for various applications. The choice between baseband and broadband transmission depends on the specific application and the type of signals being transmitted.