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What is the typical impedance of a micro coaxial cable

When working with electronics, robotics, or high-frequency communication systems, understanding the properties of cables is crucial. One common question is: ​What is the typical impedance of a micro coaxial cable? In this article, we’ll break down the answer in simple terms, explain why impedance matters, and help you choose the right cable for your needs.

​What Is a Micro Coaxial Cable?

Micro coaxial cables are miniature versions of traditional coaxial cables, designed for high-frequency signal transmission in compact spaces. They’re widely used in applications like:

• Medical devices (e.g., endoscopes)
• Drones and robotics
• High-speed data communication (e.g., HDMI, USB)
• Military and aerospace systems

These cables have a central conductor, insulating dielectric layer, shielding, and an outer jacket. Their small size (often less than 1 mm in diameter) makes them ideal for tight spaces without sacrificing performance.

​What Is Impedance, and Why Does It Matter?

Impedance (measured in ohms, Ω) describes the resistance a cable offers to alternating current (AC) signals. It’s critical for ​signal integrity: mismatched impedance can cause reflections, signal loss, or distortion, especially in high-frequency applications like video transmission or RF systems.

​Typical Impedance of Micro Coaxial Cables

Most micro coaxial cables are designed with ​50 Ω or 75 Ω impedance:

1. ​50 Ω Cables
   • Common in radio frequency (RF) systems, wireless communications, and test equipment.
   • Balances power handling and signal loss for high-frequency applications.
2. ​75 Ω Cables
   • Widely used in video transmission (e.g., CCTV, TV antennas) and digital audio.
   • Optimized for minimal signal attenuation over longer distances.

​Why Are 50 Ω and 75 Ω Standards?

The 50 Ω standard emerged from mid-20th-century RF engineering as a compromise between power handling and low loss. The 75 Ω standard was adopted for broadcast TV due to its lower attenuation at video frequencies. These standards ensure compatibility between devices and cables.

​How to Choose the Right Impedance

1. ​Match Your Device Requirements
   Check your equipment’s specifications. Using a 50 Ω cable with a 75 Ω system (or vice versa) can degrade performance.
2. ​Consider Signal Frequency
   • For RF, radar, or Wi-Fi (above 1 GHz), 50 Ω is typical.
   • For video, cable TV, or digital audio, 75 Ω is standard.
3. ​Shielding and Flexibility
   Micro coax often includes multi-layer shielding (e.g., braided + foil) to prevent interference. For bend-heavy applications (e.g., robotics), choose a highly flexible variant.

Testing and Verifying Impedance

To ensure your cable meets specifications:

• Use a ​Time Domain Reflectometer (TDR) to measure impedance.
• Consult manufacturer datasheets for certified values (e.g., Huber+Suhner, TE Connectivity).

​Key Takeaways

• Most micro coaxial cables have ​50 Ω or 75 Ω impedance.
• ​50 Ω is ideal for RF and high-frequency systems.
• ​75 Ω excels in video and long-distance signal transmission.
• Always match cable impedance to your devices for optimal performance.