Extremely thin coaxial cable length and signal attenuation full analysis

In high-speed signal transmission or precision imaging equipment design, engineers often face a problem: how long can a very thin coaxial cable be before the signal shows significant attenuation? This directly affects the stability of the product and the final display effect. This article will gradually analyze this issue from application scenarios, attenuation principles to control methods.

Why pay attention to the length of ultra-fine coaxial cables?
In scenarios such as high-frequency signal transmission, display module connection, and radio frequency communication, ultra-thin coaxial cables are widely used due to their small diameter and good flexibility. Compared with traditional thick coaxial cables, they are more suitable for wiring in limited spaces, such as medical endoscopes, flat panel displays, or camera modules. However, there is no fixed answer to how long they can be, as the signal will gradually attenuate with increasing length.

Second, the feasible length range of ultra-fine coaxial cables
The length mainly depends on the signal frequency and the characteristics of the cable. In low-frequency applications, even tens of megahertz of signals extended to tens of meters can still have acceptable attenuation. In high-frequency applications, when the frequency reaches hundreds of megahertz or even thousands of megahertz, even extremely thin coaxial cables of tens of centimeters can experience significant signal loss. In design, the reference limit is often taken as "3 dB attenuation," which means that when the signal strength drops to half of its original value, the cable length is approaching the critical value.

Three, the main factors affecting attenuation
Conductor diameter and material: The finer the conductor, the greater the resistance and the higher the loss. Using silver-plated conductors and low dielectric loss materials (such as PTFE or FEP) can improve performance.
Frequency and its High-Low: The higher the frequency, the more obvious the skin effect and medium loss will be, resulting in more severe attenuation.
Connectors and interfaces: each connector introduces additional losses, and the cumulative impact should not be ignored.
Cabling method: The extremely thin coaxial cable is soft but fragile, and excessive bending can damage the shielding layer or medium structure, leading to local attenuation and signal reflection.

Four, methods of controlling signal attenuation
Shorten transmission distance: avoid redundant cable length, design as compact as possible.
Select low-loss wire materials: use high conductivity and low dielectric loss materials.
Reduce connection points: Try to minimize intermediate joints and conversion interfaces.
Optimize cable routing radius: Maintain a reasonable bending radius and avoid sharp turns.
Compensation is necessary: In situations where attenuation is extremely sensitive, amplifiers or equalizers can be installed, but the "nearest transmission" strategy is more commonly used in most miniature applications.

The extremely thin coaxial cable does not have a unified "maximum length." It needs to be determined based on the frequency band, material characteristics, and application scenario. Under low-frequency conditions, transmission of tens of meters is acceptable; in high-frequency situations, it may only be able to reach tens of centimeters. To effectively control attenuation, it is necessary to reasonably plan the length, select materials, and arrange wiring methods during the design stage.
I amSuzhou Huichengyuan Electronics,Long-term focused on the design and customization of high-speed cable harnesses and extremely thin coaxial cable harnesses, committed to providing customers with stable and reliable high-speed interconnect solutions. If you have any related needs or want to learn more, please feel free to contact:Manager Zhang 18913228573 (WeChat same number)。