Shielded cables, also known as screened cables, are electrical cables designed with an additional layer of shielding material to protect the signals carried within the cable from external electromagnetic interference (EMI) and radio frequency interference (RFI). The shielding layer helps to contain the electromagnetic fields generated by the conductors within the cable and prevents external electromagnetic fields from interfering with the signals. Shielded cables are commonly used in applications where signal integrity is critical, such as data transmission, telecommunications, audio/video, and industrial automation.

Here are some common types of shielded cables:

1. Foil Shielded Cable:

   • Foil shielded cables feature a thin layer of metallic foil, such as aluminum or copper, wrapped around the insulated conductors. The foil shield provides excellent protection against EMI and RFI by acting as a barrier that reflects and absorbs electromagnetic radiation. Foil shielding is often used in twisted pair cables and flat ribbon cables.

2. Braided Shielded Cable:

   • Braided shielded cables consist of multiple strands or wires of metal, such as copper or aluminum, woven into a mesh or braid pattern around the insulated conductors. The braided shield offers superior flexibility, mechanical strength, and coverage compared to foil shielding. Braided shielding is commonly used in cables for audio, video, instrumentation, and control systems.

3. Spiral Shielded Cable:

   • Spiral shielded cables feature a helical or spiral-wrapped metal shield around the insulated conductors. The spiral shield provides good flexibility and coverage while offering adequate EMI and RFI protection. Spiral shielding is often used in flexible cables and cords for applications such as microphone cables, audio cables, and portable electronic devices.

4. Metallic Tape Shielded Cable:

   • Metallic tape shielded cables utilize a metallic tape, such as aluminum or copper, wrapped longitudinally around the insulated conductors. The metallic tape shield provides effective EMI and RFI protection while offering good flexibility and ease of termination. Metallic tape shielding is commonly used in high-voltage cables, power cables, and industrial control cables.

5. Combination Shielded Cable:

   • Combination shielded cables combine multiple shielding techniques, such as foil shielding with a braided or spiral shield, to provide enhanced EMI and RFI protection. These cables offer the benefits of both foil and braided shielding and are commonly used in high-performance cables for data transmission, networking, and industrial automation.

These types of shielded cables provide varying degrees of EMI and RFI protection, flexibility, mechanical strength, and ease of termination, allowing them to be used in a wide range of applications across different industries. The choice of shielded cable type depends on factors such as the application requirements, frequency range, environmental conditions, and budget considerations.