"- ax" is an abbreviation for "- axis" and refers to the longitudinal axis of the cable. When it is abbreviated to "- ax", it also implies the word "cable". This is an overview of common "axis" coaxial cables. Coaxial cable consists of two conductors that share the same axis. To do this, and to separate them electrically, at least one must be cylindrical and larger than the other in diameter. Coaxial cables are inherently unbalanced, which may be bad news about EMI immunity, but this is usually overcome by the efficiency of their connection to high-frequency antennas. The choice of ABC cable is usually determined by the antenna design itself.
When it is mentioned above that "at least one must be cylindrical", this acknowledges the use of hollow central conductors used in some large cables to take advantage of the skin effect (at high frequencies), in which almost all signals are confined outside the command. The core material can be eliminated with little effect on performance, and the weight or cost can be reduced.
Interestingly, there is a specially designed coaxial cable itself that can be used as an antenna. They are made up of slits or perforated shields and are usually poorly designed, but leak enough signals to the central conductor to radiate over the entire length. For example, they are used in subway tunnels to provide RF access to systems that operate underground.
There are many coaxial cable designs, including those with complex, multiple shielding, and many different cable diameters, with correspondingly higher losses in smaller (central conductor meter) meters and lower losses in larger instruments. There are many differences in insulating materials, which affect safety, flexibility and signal processing. The technology is constantly changing.
Multiple shields in coaxial cables are usually "unitized", that is, they are electrically connected to each other.
Three axes are similar to coaxial cables because all conductors share the same axis, but three of them. At least two of these must be cylindrical and insulated from each other and from the third conductor.
Triax can be used in many PE cable applications, but provides additional independent shielding-not just another layer of shielding. External shielding covers the internal "coaxial cable", which can add additional EMI protection measures.
Quadrax is a quad-core cable. Two separate shields share the same axis, but the other two conductors are twisted pairs. Like the triaxial, the shielding layers are insulated from each other, which helps to improve noise resistance. It is also very suitable for limiting noise signals (such as pulses) to interfere with other low-level circuits. This explains its application in radar display bus. Its * major use is less than 50 MHz.
The Twinax also has two stranded conductors, but they are surrounded by a (or double but not isolated) shield. Twinax almost completely violates the coaxial idea-unless you consider the "pseudo" axis of twisted pair. Historically, the name was designed to imply "next-generation" coaxial cable, mainly in data communications applications, although twinax is no longer the preferred medium for new applications in the market. )
There are many changes in all "shaft" designs, but a basic understanding of what they are called may help to make sound application decisions, or at least better understand the decisions of avionics and engineers.