How to make ultra-thin coaxial cables quieter? Antenna interference techniques in high-frequency systems

In modern electronic systems, micro coaxial cable has become a key channel for high-density signal transmission, widely used in scenarios that require extreme space and signal quality, such as laptops, foldable screen smartphones, medical equipment, AR/VR headsets, and other devices. This type of cable features a compact structure and excellent flexibility, maintaining stable signal transmission even in environments with frequent bending. At the same time, its outer conductor also serves as a shielding function, effectively preventing electromagnetic interference (EMI) and external noise intrusion. However, even with excellent design, micro coaxial cables may still encounter various signal interference issues in complex applications.

One, common signal interference issues with ultra-fine coaxial cables
The imperfect shielding layer leads to interference.
Although the coaxial structure itself has good shielding characteristics, if the shielding layer resistance is too high, it may cause common-mode current or residual voltage in the low-frequency band (such as below 30 MHz), affecting signal reception. In addition, when the shielding layer adopts a copper mesh weaving structure, the weaving gap may also allow high-frequency noise to渗透, reducing the purity of the signal.
Earth loop and sheath current interference
When the ground potential of the two connected devices is not consistent, it may form sheath current flowing along the shielding layer, which is superimposed on the effective signal, causing signal distortion or noise interference.
Connector contact is poor or impedance mismatch
If the harness cannot achieve a 360° full shielding contact with the connector, or if the characteristic impedance mismatch is not proper, it may lead to signal reflection, image ghosting, or even data errors.
Power interference and switch noise radiation
High-frequency switching power supplies often generate spurious radiation signals. If there are no good filtering measures, these noises may be coupled into the coaxial system through cables, causing cross-talk or performance degradation.

Two, effective interference suppression measures
Enhance the shielding structure
The composite shielding design using "metal foil + copper braided layer" can provide excellent interference suppression effect simultaneously in both low and high frequency ranges.
② Suppress sheath current interference
Ferrite Bead/Choke: Installed at the end of the cable or near the equipment, it can effectively absorb high-frequency common-mode noise.
Capacitive coupling ground isolator: Suitable for high-frequency systems, capable of blocking low-frequency ground loop interference while ensuring normal transmission of the signal path.
Ensure impedance matching and reliable connection
Select coaxial cables and connectors with characteristic impedance matching (such as 45 Ω or 50 Ω) and ensure complete shielding contact at the interface, which can significantly reduce signal reflection and loss.
Source control and rational wiring
Increase filtering circuits or metal shielding at interference sources (such as switch mode power supplies) to weaken scattered radiation.
In system layout, avoid parallel wiring of the same axis with strong interference signal lines; use metal tube shielding or staggered wiring methods to reduce coupling when necessary.
Micro coaxial cable, although its size is extremely small, its structural design and shielding performance are crucial for signal quality. In actual applications, attention should be focused on shielding integrity, ground loop management, impedance matching, and power noise control. By reinforcing the shielding layer, installing common-mode filters, optimizing wiring and termination methods, interference can be effectively reduced, ensuring the integrity and stability of high-speed signals.
I amSuzhou Huichengyuan ElectronicFocused on the research and development, as well as customization, of high-speed signal cables and ultra-fine coaxial cables, we are committed to providing customers with high-performance and reliable interconnection solutions. For more product information or customization services, please contact us:Manager Yin 18913280527 (WeChat same number)。