DC-BLOCK is a RF coaxial adapter that blocks DC signals and allows RF signals to pass through. It uses capacitors to block DC and widely used to protect sensitive RF components from DC.

There are three types of DC blocks:

Internal DC block, which use a capacitor to series-connected with the inner or center conductor of the coaxial cable

An external DC block, which use a capacitor to series-connected with the shield conductor of the coaxial cable

Inner/outer DC block, the capacitor is used to series-connected with both the inner conductor and the outer conductor

The parameters of DC block:

·Working frequency range

·Insertion loss

·Return loss

·Connection type

·Maximum DC blocking voltage

DC blocks are specified with mainly two types of impedance, usually 50 or 75 Ω.