Do you know the shielding methods of coaxial cables?

Single-layer braided shielding consists of one braided layer with a coverage rate of 70% to 95%. Its shielding effect is about -50dB, and the single-layer shielded cable is often used below 1GHz. In RF test and measurement, single shielded coaxial cable is not recommended. Someone once used a single-layer shielded test cable assembly in high-power measurement, and the result was unstable power readings due to electromagnetic leakage. After switching to a double-shielded cable, the instability disappeared immediately.

The double-layer braided shield is composed of two layers of braid, and its shielding effect is -75dB~-85dB, and the typical application can reach 6GHz. In general RF testing, double shielded cables are probably the most widely used.

The three-layer shield is composed of two layers of braided shields and a layer of foil shielding. Some layers are made of wound copper tape, and the shielding effect can reach -90~-100dB. Some cables and Aobo cables for EMC test applications use this structure.

The inner shield of the double-layer (wound + braided) screen adopts winding copper tape, and the outer shield adopts braiding. The coverage rate is 100%, and the shielding effect can reach -100dB. Many microwave cables use this structure.

The solid-state shield is made of aluminum tube or copper tube, with a coverage rate of 100%, achieving a complete shielding effect (better than -120dB). Typical products are semi-rigid coaxial cables. This kind of cable can only be bent once and is often used for interconnection inside equipment. There is no need to consider the mutual interference between cables when designing and routing. Intermodulation measurement system. Another type of cable that can be classified as a solid shield is the corrugated copper tube cable, which is relatively easier to bend and is often used in antenna feeder systems.