DC Blocks are coaxial components that prevent the flow of audio and direct current

Direct current

Direct current is the unidirectional flow of electric charge. Direct current is produced by such sources as batteries, thermocouples, solar cells, and commutator-type electric machines of the dynamo type. Direct current may flow in a conductor such as a wire, but can also flow through...

 (DC) frequencies while offering minimum interference to RF signals. There are three basic forms of DC blocks. “Inner only” models have a capacitor

Capacitor

A capacitor is a passive two-terminal electrical component used to store energy in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors separated by a dielectric ; for example, one common construction consists of metal foils separated...

 in series with the center conductor, “outer only” models have a capacitor in series with the outer conductor, and “inner/outer” models have capacitors in series with both the inner and outer conductors. The insulation material on the outer models is non-conductive. Applications include ground loop elimination, signal source modulation leakage suppression, system signal-to-noise ratio

Signal-to-noise ratio

Signal-to-noise ratio is a measure used in science and engineering that compares the level of a desired signal to the level of background noise. It is defined as the ratio of signal power to the noise power. A ratio higher than 1:1 indicates more signal than noise...

improvement, test setup isolation and other situations where undesired DC or audio current flows in the system.