Copper vs. Fiber Optic Cables: A Comprehensive Comparison

This article compares copper and fiber optic cables, highlighting their differences in data communication. It also discusses the advantages and disadvantages of each medium.

Introduction

Data transmission systems comprise a source (transmitter), a destination (receiver), and a transmission medium connecting them. This medium can be either guided or unguided. Communication relies on electromagnetic (EM) waves.

In guided media, waves travel through a solid physical medium like copper wires or fiber optic cables. Copper wires can be twisted pairs or coaxial cables. Unguided media involve transmitting EM waves through the atmosphere or outer space. Transmission through guided media is known as wired communication, while transmission through unguided media is known as wireless communication.

Copper Wire

Copper boasts an electrical conductivity of 5.88 x 10⁷ Ohm-meter and a thermal conductivity of 39.5 KW/m²K°. This allows copper wires to handle high current loads with thinner wires for fine-pitch packages, offering improved heat transfer efficiency.

Copper also possesses numerous mechanical advantages, including higher tensile strength, increased ductility and stiffness, and reduced molding sway. This contributes to high mechanical stability and long-term reliability.

In data communication, copper offers low delay, medium bandwidth, and varying path loss. Twisted pair and coaxial cables are common copper wire categories used for data transmission.

Twisted pairs involve twisting copper wires into a spiral shape to minimize noise and crosstalk. Coaxial cable is an improved version, featuring conductors insulated from each other and enclosed in a polyethylene jacket.

There are two types of twisted pairs:

• UTP (Unshielded Twisted Pair): Categories range from Cat-1 to Cat-8.2 based on construction, bandwidth, and applications.
• STP (Shielded Twisted Pair):

Copper wires find applications in telephone cables, electric wires, ethernet cables, and more.

Advantages and Disadvantages of Twisted Pair Cable

Advantages:

• Inexpensive
• Often available in existing phone systems
• Well-tested and easy to acquire

Disadvantages:

• Susceptible to RFI (Radio Frequency Interference) and EMI (Electromagnetic Interference)
• Not as durable as coaxial cable
• Doesn’t support higher speeds like other media

Advantages and Disadvantages of Coaxial Cable

Advantages:

• Fairly resistant to RFI and EMI
• Supports faster data rates than twisted pair
• More durable than twisted pair

Disadvantages:

• Can be affected by strong interference
• More costly than twisted pair
• Bulkier and more rigid than twisted pair

Fiber Optic System

The growing demand for faster and higher-volume data transmission over longer distances has driven the development of fiber optic cables, superseding traditional copper wires. Fiber optic cables transmit modulated light, making them immune to interference from electrical devices. They are the preferred choice for secure networks.

Fiber optic cables transmit television, voice, and digital data signals via light waves through flexible, hair-like strands of glass and plastic.

Construction

Fiber optic cables consist of thousands of clear glass fiber strands, each about the thickness of a human hair. Key components include:

• Core: The thin glass center where light travels.
• Cladding: The outer material surrounding the core, reflecting light back into the core.
• Coating: A plastic coating that protects the fiber from damage and moisture.
• Strength Member: Protects the core from damage during installation or from being crushed.
• Outer Jacket: The outermost layer, protecting the cable’s outer coating.

Fiber optic cables are classified based on:

• Refractive Index Variation: Step index and graded index.
• Mode: Single mode and multimode (refer to single mode step index vs. multimode graded index fiber and single mode vs. multimode fiber for details).

Advantages and Disadvantages of Fiber Optic System

Advantages:

• Highly secure
• Unaffected by RFI and EMI
• Offers the highest bandwidth available
• Very durable

Disadvantages:

• Extremely costly in terms of product and service
• Requires sophisticated tools and methods for installation
• Complex to lay out and design

Difference Between Copper and Fiber in Data Communication

The following table highlights the key differences between copper and fiber optic cables, facilitating a comparison in the data communication domain:

Conclusion

The comparison highlights that both copper and fiber optic technologies coexist, dictated by specific requirements for data rate, distance, and other factors. Copper wire is suitable for shorter distances and moderate data rates, while fiber optic excels over longer distances with very high data rates.