Abstract: A DC bias device for radio-frequency transmission systems of high power and low intermodulation connected between an originating station and a receiving station for an RF signal fed along a transmission line. Direct current is supplied from a source to the transmission line along a branch joined to the transmission line at a junction formed between the originating station and the receiving station. An open-circuit stub is formed along the transmission line between the transmitting station and the junction. A short-circuit stub is formed along the DC-supply branch between the source and the junction to the transmission line. The impedance (Zop) of the open-circuit stub, and the distance of the free heads of the near ends of the two stubs preferably is as low as possible.

Abstract: A lightning suppression system comprising a directional coupler, a quarter-wavelength stub, a first cylindrical capacitor, a second cylindrical capacitor and a lightning suppression circuit. Each of the cylindrical capacitors has an inner conductor element, an outer conductive tube and a dielectric material. Direction coupler acts to block direct current and low frequency signals from passing therethrough. The quarter-wavelength stub comprises a helicoid and acts to reflect radio frequency signals back to the transmission line while allowing direct current and low frequency signals to flow therethrough. First cylindrical capacitor and second cylindrical capacitor combine to form a low pass filter which allows direct current and low frequency signals to flow through while blocking other signals. The lightning suppression circuit suppresses high voltage direct current and low frequency signals such as those produced by near lightning strikes.