Bandpass filter with capacitor setting frequency - gives extra attenuation at frequencies below lower cut=off frequency

摘要

The bandpass filter consists of two resonant circuits inductively coupled by a loop conductor and realised using conductors. A capacitor (14) is located in the conductor loop (8) and its capacitance is adjusted to the inductance of the conductor or coupling loop (8) such that the resonant frequency lies above the lower cutoff frequency of the filter. The conductor loop is formed by the connection wires (12,13) of the capacitor. These wires are connected electrically and mechanically to the outer conductor casing (5) of the filter.