Double-T structure HF cut=off filter - creates symmetrical pass band for low voltage networks used for carrier frequency data transmission.

摘要

The structure includes an elongate coil (L1) between one input (E1) and an output (A1). This is bridged by three resistors (R1 - R3) connected in series. A shunt coil (L2, L3) is connected at the nodes between each pair of resistors (R2 and R3, or R1 and R2). The coil outputs are connected together and are connected to a shunt capacitor (C1). The output of the latter is connected to the base line between a second input (E2) and output (A2) of the filter. The middle resistor (R2) is carrier frequency dependent. This resistor allows the filter to be automatically tuned to the carrier frequency. ADVANTAGE - Has required filtering effect in set frequency range without requiring manual tuning.