Direction finder antenna apparatus

Claim 1

A DIRECTION FINDING SYSTEM COMPRISING: FIRST AND SECOND ANTENNAS ORIENTED TO SIMULTANEOUSLY RECEIVE A SIGNAL RADIATED BY A SIGNAL SOURCE IN A PREDETERMINED REGION OF SPACE, SAID FIRST ANTENNA BEING SENSITIVE TO A PREDETERMINED POLARIZATION OF THE RECEIVED SIGNAL RELATIVE TO SAID FIRST ANTENNA TO PRODUCE A FIRST SIGNAL IN RESPONSE THERETO AND SAID SECOND ANTENNA BEING ADAPTED TO PRODUCE A SECOND SIGNAL IN RESPONSE TO THE RECEIVED SIGNAL IRRESPECTIVE OF THE DIRECTION OF POLARIZATION THEREOF RELATIVE TO SAID SECOND ANTENNA, SAID SECOND ANTENNA BEING ROTATED AT A CONSTANT SPEED AND INCLUDING MEANS FOR SHIFTING THE PHASE OF SAID SECOND SIGNAL RELATIVE TO SAID FIRST SIGNAL IN ACCORDANCE WITH THE ROTATIONAL DISPLACEMENT OF SAID SECOND ANTENNA RELATIVE TO SAID FIRST ANTENNA, THE FIELD PATTERN OF SAID SECOND ANTENNA BEING SUBSTANTIALLY SYMMETRICAL ABOUT ITS AXIS OF ROTATION TO PRODUCE SAID SECOND SIGNAL AT A SUBSTANTIALLY CONSTANT VOLTAGE AMPLITUDE OF THE ROTATIONAL DISPLACEMENT OF SAID SECOND ANTENNA; MEANS FOR ADDING THE INSTANTANEOUS VALUES OF SAID FIRST AND SECOND SIGNALS TO PRODUCE A MODULATED RESULTANT SIGNAL HAVING A PERIODICALLY VARYING ENVELOPE; RECEIVER CHANNEL MEANS FOR DEMODULATING SAID RESULTANT SIGNAL TO PRODUCE A DETECTED SIGNAL; SIGNAL SOURCE MEANS FOR GENERATING A PERIODIC REFERENCE SIGNAL THAT IS SYNCHORNIZED WITH THE ROTATION OF SAID SECOND ANTENNA; A PHASE DISCRIMINATOR OPEABLE IN RESPONSE TO SAID DETECTED AND REFERENCE SIGNALS TO PRODUCE A VARYING OUTPUT VOLTAGE WHOSE MAGNITUDE AND POLARITY CORRESPONDS TO THE PHASE DIFFERENCE BETWEEN SAID DETECTED AND REFERENCE SIGNALS; AND VARIABLE PHASE SHIFTER APPARATUS OPERABLE IN RESPONSE TO SAID OUTPUT VOLTAGE TO PHASE SHIFT SAID REFERENCE SIGNAL IN SUCH A MANNER AS TO REDUCE THE PHASE DIFFERENCE BETWEEN SAID DETECTED AND REFERENCE SIGNALS TO ZERO, THEREBY TO REDUCE THE OUTPUT VOLTAGE TO ZERO, SAID PHASE SHIFT APPARATUS INCLUDING MEANS FOR RELATING THE EXTENT OF THE PHASE SHIFT EXPERIENCED BY SAID REFERENCE SIGNAL TO THE ANGLE OF ARRIVAL OF THE RECEIVED SIGNAL TO PROVIDE A DIRECT READING OF THE DESIRED DIRECTIONAL INFORMATION.