Abstract: A coaxial cable isolator is presented which serves to reduce or eliminate ground loop induced hum and interference in audio-video entertainment systems connected to externally grounded antenna signal sources. A linearly arranged array of discrete monolithic capacitive elements couples two ground plane areas fabricated on a circuit board, which are connected respectively to the shield conductors of the input and output coaxial cables between which DC and audio frequency isolation is desired. Resistive elements are provided for the dissipation of accumulated static charges, and a gas discharge transient suppressor protects equipment connected to the isolator's output from voltages induced by nearby lightning strikes.