Coaxial Cable is a cable with two concentric conductors, and the conductor and shield layer share the same axis.The most common coaxial cable consists of insulated copper wire conductors, the outside of the inner insulating material is ring shielding layer, and then the entire cable is covered by polyvinyl chloride or Teflon sheath.
The function of shield layer is for anti-interference and electromagnetic/EMI proofing.
Coaxial cable is mainly used in microwave transmission, this is a very high speed of data.
The main function it is the most important function is via dimensional coordination of the inner conductor and outer conductor, realize accurately impedance matching, make transmission efficiency of power achieve high level, this is usually for frequency higher than 10 MHZ signal.
Another obvious function is to shield external interference, so that all kinds of stray signals in the external space are isolated outside the shielding layer, so that the signal is complete without distortion and the data is exact without error.