Frequency responsive network

Claim 1

A FREQUENCY SELECTIVE NETWORK COMPRISING IN COMBINATION, MEANS PROVIDING AN INPUT TERMINAL, AND A COMMON TERMINAL, INPUT CIRCUIT MEANS INCLUDING A FIRST RESISTIVE CIRCUIT ELEMENT AND A FIRST REACTIVE CIRCUIT ELEMENT SERIALLY CONNECTED IN THE ORDER NAMED BETWEEN SAID INPUT AND COMMON TERMINALS, AND A SECOND REACTIVE CIRCUIT ELEMENT, AND A SECOND RESISTIVE CIRCUIT ELEMENT CONNECTED IN THE ORDER NAMED BETWEEN SAID INPUT AND COMMON TERMINALS, THE TIME CONSTANT OF SAID FIRST RESISTIVE ELEMENT AND SAID FIRST REACTIVE ELEMENT BEING EQUAL TO THE TIME CONSTANT OF SAID SECOND RESISTIVE ELEMENT AND SAID SECOND REACTIVE ELEMENT, FIRST IMPEDANCE ISOLATION MEANS INCLUDING AN INPUT CIRCUIT COUPLED ACROSS SAID FIRST REACTIVE CIRCUIT ELEELEMENT, AND AN OUTPUT TERMINAL, SECOND IMPEDANCE ISOLATION MEANS INCLUDING AN INPUT CIRCUIT COUPLED ACROSS SAID SECOND RESISTIVE CIRCUIT ELEMENT, AND AN OUTPUT TERMINAL, SUMMING CIRCUIT MEANS INCLUDING A THIRD RESISTIVE CIRCUIT ELEMENT AND A THIRD REACTIVE CIRCUIT ELEMENT CONNECTED IN SERIES BETWEEN THE OUTPUT TERMINALS OF SAID FIRST AND SECOND IMPEDANCE ISOLATION MEANS, THE TIME CONSTANT OF SAID SUMMING CIRCUIT MEANS BEING SUBSTANTIALLY EQUAL TO THE TIME CONSTANT OF SAID FIRST RESISTIVE CIRCUIT ELEMENT AND SAID FIRST REACTIVE CIRCUIT ELEMENT, OUTPUT CIRCUIT MEANS COUPLED BETWEEN THE JUNCTION OF SAID THIRD RESISTIVE CIRCUIT ELEMENT AND SAID THIRD REACTIVE CIRCUIT ELEMENT AND SAID COMMON TERMINAL, AND MEANS FOR ADJUSTING ONE OF SAID THIRD RESISTIVE CIRCUIT ELEMENTS AND THIRD REACTIVE CIRCUIT ELEMENTS TO TUNE SAID FREQUENCY SELECTIVE NETWORK.