A cable for transmitting high-frequency electrical signals with low loss. It is composed of an internal conducting wire surrounded by an insulating dielectric which is further protected by a metal shield. The impedance of coax is a product of the radius of the central conductor, the radius of the shield, and the dielectric constant of the insulation. In most satellite and SMATV systems, the coax impedance is 75 ohms.

Coaxial cables connect the output of the LNB with the input of the satellite receiver. Both the signal and the switching voltage for electronically switched polarizers can be transmitted via coax. Coax is characterized by a characteristic impedance and signal losses per unit distance. 75-ohm cables are nearly always in satellite reception systems. Signal losses vary with the construction of the cable as well as the frequency. Higher frequencies are attenuated more strongly. For example, RG-6 coax has approximately 24.6 dB and 27.9 dB per 100 meters at a signal frequency of 950 and 1450 MHz, respectively.