(1) Coaxial RF cable

Coaxial RF cable is the most commonly used structural type. Because its inner and outer conductors are in concentric position, electromagnetic energy is confined to the medium between the inner and outer conductors, so it has obvious advantages such as small attenuation, high shielding performance, wide frequency band and stable performance. It is usually used to transmit radio frequency energy from 500 kHz to 18 kHz.

At present, there are two kinds of commonly used RF coaxial cables: 50Ω and 75Ω RF coaxial cables. The RF coaxial cable with characteristic impedance of 75Ω is often used in CATV network, so it is called CATV cable, and its transmission bandwidth can reach 1GHz. At present, the transmission bandwidth of common CATV cable is 750MHz.   

(2) Symmetric RF cable

The electromagnetic field of symmetrical RF cable loop is open. Because of the radiation of electromagnetic energy at high frequency, the attenuation increases and the shielding performance is poor. Coupled with the influence of atmospheric conditions, it is usually seldom used. Symmetric RF cables are mainly used in the case of low RF or symmetrical feed.  

(3) Spiral RF cable

Conductors in coaxial or symmetrical cables can sometimes be made into spiral coils, so as to increase the inductance of the cable, thereby increasing the wave impedance of the cable and delaying the transmission time of electromagnetic energy. The former is called high-resistance cable, and the latter is called delay cable. If the winding density of the spiral coil is different along the length direction, the variable resistance cable can be made.