Key Features to Look for in Double Shielded Coaxial Cables
Coaxial cables are essential components of many electronic systems, transmitting signals between devices. Double shielded coaxial cables offer enhanced protection against electromagnetic interference (EMI) and radio frequency interference (RFI), making them ideal for use in demanding applications. When selecting double shielded coaxial cables, several key features should be considered to ensure optimal performance.
Impedance
Impedance matches the electrical resistance and reactance of a cable to the equipment it connects. Double shielded coaxial cables typically have an impedance of 50 or 75 ohms, which should match the impedance of the source and load devices. Mismatched impedance can result in signal reflections, reducing signal quality and introducing errors into the system.
Conductor Material
The conductor material is responsible for carrying the signal. Copper is widely used due to its high conductivity and low resistance. Double shielded coaxial cables may have a solid copper conductor or a stranded copper conductor, with the latter providing increased flexibility. Other conductor materials, such as silver, gold, or aluminum, may also be used for specific applications.
Shield Construction
Double shielded coaxial cables have two layers of shielding to provide enhanced EMI and RFI protection. The outer shield is usually braided, while the inner shield is typically a metal foil. The braiding provides a physical barrier against EMI, while the foil shields against higher-frequency RFI. The overlap and coverage of the shielding are critical for effective protection.
Dielectric Insulation
The dielectric insulation material separates the conductor from the shield and prevents signal loss. Common dielectric materials include polyethylene (PE), polyvinyl chloride (PVC), and Teflon. Each material has different properties, such as flexibility, durability, and signal attenuation. Selecting the appropriate dielectric insulation depends on the specific application requirements.
Outer Jacket
The outer jacket protects the cable from environmental factors such as moisture, abrasion, and chemicals. Different jacket materials, such as polyethylene, PVC, or polyurethane, offer varying degrees of protection and flexibility. The outer jacket thickness and construction also influence the cable’s durability and handling ease.
Additional Considerations
Beyond the key features mentioned above, other factors to consider when selecting double shielded coaxial cables include:
– Connector type: The type of connector used (e.g., BNC, F-connector) depends on the devices and application requirements.
– Cable length: The cable length should be appropriate for the application, considering signal attenuation and voltage drop.
– Bandwidth: The bandwidth determines the range of frequencies the cable can transmit without significant signal loss.
– Attenuation: Attenuation measures the signal loss per unit length and influences the maximum distance the cable can be used.
By considering these key features and additional factors, engineers and technicians can select the optimal double shielded coaxial cables for their specific applications, ensuring reliable and high-quality signal transmission.