Geophysical exploration apparatus

Claim 1

GEOPHYSICAL EXPLORATION APPARATUS THAT UTILIZES ELECTRIC FIELDS ESTABLISHED AT THE EARTH''S SURFACE BY ATMOSPHERIC ELECTRICITY, THE ELECTRIC FIELDS RESPECTIVELY BEING ESTABLISHED AT DIFFERENT FREQUENCIES OVER A RANGE OF FREQUENCIES, SAID APPARATUS COMPRISING: FIRST AND SECOND MEANS COUPLED TO THE ELECTRIC FIELDS AND ADAPTED TO RESPECTIVELY RESPOND TO FIRST AND SECOND COMPONENTS THEREOF TO PRODUCE FIRST AND SECOND VOLTAGES WHOSE AMPLITUDES VARY AS THE MAGNITUDES OF THE COMPONENTS OVER THE RANGE OF FREQUENCIES, SAID FIRST AND SECOND MEANS RESPECTIVELY INCLUDING FIRST AND SECOND ANTENNA MEANS ADAPTED TO RESPECTIVELY RECEIVE HORIZONTAL AND VERTICAL COMPONENTS OF THE ELECTRIC FIELDS OVER THE RANGE OF FREQUENCIES AND TO RESPECTIVELY DEVELOP FIRST AND SECOND PLURALITIES OF SIGNALS IN RESPONSE THERETO, A SWEEP OSCILLATOR CIRCUIT FOR GENERATING A SWEEP SIGNAL WHOSE FREQUENCY RECURRENTLY VARIES IN A PRESCRIBED MANNER BETWEEN LOWER AND UPPER LIMITS, FIRST AND SECOND MIXER CIRCUITS RESPECTIVELY COUPLED BETWEEN SAID FIRST AND SECOND ANTENNA MEANS AND SAID SWEEP OSCILLATOR TO HETERODYNE SAID FIRST AND SECOND PLURALITIES OF SIGNALS AGAINST SAID SWEEP SIGNAL TO PRODUCE FIRST AND SECOND INTERMEDIATE-FREQUENCY SIGNALS WHOSE AMPLITUDES VARY AS THE AMPLITUDES OF SAID FIRST AND SECOND PLURALITIES OF SIGNALS, AND FIRST AND SECOND DETECTOR MEANS RESPECTIVELY COUPLED TO SAID MIXER CIRCUITS FOR PRODUCING SAID FIRST AND SECOND VOLTAGES; THIRD MEANS COUPLED TO SAID FIRST AND SECOND MEANS AND OPERABLE IN RESPONSE TO THE FIRST AND SECOND VOLTAGES THEREFROM TO PRODUCE A THIRD VOLTAGE WHOSE AMPLITUDE AT ANY INSTANT IS PROPORTIONAL TO SAID FIRST VOLTAGE DIVIDED BY SAID SECOND VOLTAGE AT THAT INSTANT; AND A RECORDER MECHANISM COUPLED TO SAID THIRD MEANS FOR PRESENTING SAID THIRD VOLTAGE AS A FUNCTION OF FREQUENCY OVER THE RANGE OF FREQUENCIES.