The signal attenuation and distortion problems faced by electronic wiring harnesses in high-frequency signal transmission are essentially energy dissipation and waveform distortion caused by factors such as dielectric loss, impedance mismatch, and external interference during the transmission path. To solve this problem, a comprehensive signal integrity assurance system needs to be formed through a multi-dimensional collaborative approach, including material optimization, structural design, impedance control, shielding technology, and system compensation.
The choice of transmission medium is fundamental to suppressing high-frequency attenuation. In high-frequency scenarios, traditional copper conductors experience current concentration on the conductor surface due to the skin effect, resulting in a reduced equivalent cross-sectional area and a significant increase in resistance. To address this, high-purity oxygen-free copper or silver-plated conductors can be used to reduce ohmic losses by lowering the conductor resistivity. Simultaneously, the dielectric layer should be made of materials with low dielectric constant and low loss factor, such as polytetrafluoroethylene (PTFE) or liquid crystal polymer (LCP). These materials can effectively reduce energy loss caused by dielectric polarization and suppress phase distortion of high-frequency signals.
Optimization of structural design is key to reducing signal distortion. Coaxial cable bundles, through their concentric structure of a central conductor, dielectric layer, metal shielding layer, and outer sheath, create a natural electromagnetic shielding cavity. This design not only maintains stable characteristic impedance but also blocks the coupling path of external electromagnetic interference through the metal shielding layer. For extremely thin coaxial cable bundles, the wire diameter, dielectric thickness, and concentricity must be strictly controlled to avoid impedance fluctuations caused by geometric errors. Furthermore, avoiding sharp-angle bends and adhering to minimum bending radius specifications can prevent structural deformation caused by mechanical stress, thereby maintaining signal transmission stability.
Impedance matching is the core method for eliminating signal reflections. When high-frequency signals encounter impedance abrupt changes in the transmission path, standing waves are formed due to reflection effects, leading to signal amplitude attenuation and waveform distortion. To solve this problem, impedance matching must be implemented throughout the signal source, transmission line, and load. For example, in high-speed differential pair designs, the impedance consistency between the cable bundle and connectors, and the PCB transition area, must be strictly controlled to avoid impedance deviations caused by geometric errors or manufacturing defects. For long-distance transmission scenarios, series or parallel termination matching techniques can be used to eliminate the impact of secondary reflections on signal quality.
Upgrading shielding technology is crucial for mitigating external interference. High-frequency signals are extremely sensitive to electromagnetic noise; electromagnetic radiation from nearby signal sources or the environment can introduce crosstalk through capacitive or inductive coupling. To enhance anti-interference capabilities, multi-layered shielding structures, such as composite shielding layers combining foil and high-density braiding, can be employed. This design not only enhances shielding effectiveness in the low-frequency band but also improves shielding coverage in the high-frequency band through gap compensation in the braided layers. Simultaneously, it is essential to ensure complete grounding of the shielding layer to prevent a decrease in shielding effectiveness due to poor grounding.
System-level compensation is a supplementary means of compensating for link losses. For long-distance or high-bandwidth links, passive optimization alone is insufficient to completely eliminate signal attenuation. In such cases, active compensation techniques, such as equalizers or retimers, can be introduced. Equalizers improve amplitude-frequency characteristics by compensating for attenuation differences in different frequency components; retimers eliminate accumulated jitter and distortion through signal regeneration technology. Furthermore, performing signal integrity (SI) simulation during the high-speed link design phase can predict link losses in advance, providing a quantitative basis for material selection and structural design.
Improved environmental adaptability extends the guarantee of signal stability. Variations in temperature and humidity can cause dielectric properties to drift, leading to deterioration in transmission characteristics. For example, the dielectric constant increases after the dielectric absorbs moisture, causing an increase in signal phase delay and insertion loss. To address this issue, dielectric materials with low hygroscopicity must be selected, and sealing designs must be implemented to prevent moisture intrusion. Simultaneously, in extreme temperature environments, matching designs based on the material's coefficient of thermal expansion are necessary to prevent structural deformation due to thermal stress.
The signal attenuation and distortion issues in high-frequency signal transmission using electronic wiring harnesses require a comprehensive approach, including material optimization, structural design, impedance control, shielding technology, system compensation, and improved environmental adaptability. These technologies support each other, collectively constructing a robust system for ensuring the integrity of high-frequency signal transmission, providing reliable physical layer support for high-frequency applications such as 5G communications, data centers, and automotive electronics.
