Variable phase shifter having greater than 180 u deg. range utilizing fixed reactances and potentiometer to effect phase shift

Claim 1

A PHASE SHIFTER FOR VARIABLY SHIFTING THE PHASE OF A SIGNAL THROUGHOUT A RANGE IN EXCESS OF 180* COMPRISING A SOURCE OF AN ALTERNATING CURRENT SIGNAL, ONE TERMINAL OF WHICH IS CONNECTED TO A POINT AT REFERENCE POTENTIAL, SAID SOURCE BEING CONNECTED ACROSS THE PARALLEL COMBINATION OF (1) TWO SERIES-CONNECTED RESISTANCES, (2) A SERIES-CONNECTED FIRST CAPACITOR AND FIRST INDUCTOR (3) A POTENTIOMETER, AND (4) A SERIES-CONNECTED SECOND CAPACITOR AND SECOND INDUCTOR, THE JUNCTIONS OF SAID TWO SERIES CONNECTED RESISTANCES AND SAID SERIES-CONNECTED FIRST CAPACITOR AND FIRST INDUCTOR BEING JOINED AND CONSTITUTING A FIRST TERMINAL, SAID POTENTIOMETER INCLUDING A WIPER CONTACT AND WIPER CONTACT OF SAID POTENTIOMETER AND THE JUNCTION OF SAID SERIES-CONNECTED SECOND CAPACITOR TERMINAL, WHEREBY ADJOINED AND CONSTITUTING A SECOND TERMINAL, WHEREBY ADJUSTMENT OF SAID WIPER CONTACT WILL SHIFT THE PHASE OF A SIGNAL APPEARING ACROSS SAID TERMINALS THROUGH A RANGE IN EXCESS OF 180*, AND A DIFFERENCE AMPLIFIER HAVING INPUTS CONNECTED ACROSS SAID FIRST AND SECOND TERMINALS, SAID DIFFERENCE AMPLIFIER BEING ARRANGED TO REFERENCE THE SIGNAL APPEARING ACROSS SAID TERMINALS TO SAID POINT AT REFERENCE POTENTIAL.