An electromagnetic geophysical exploration system comprising: a first electromagnetic transmitter configured to transmit a first waveform in a first spectrum; a first receiver configured to sense signals in the first spectrum; a second electromagnetic transmitter comprising a transmitter coil configured to transmit a second waveform in a second spectrum, the second spectrum having a frequency higher than a frequency of the first spectrum; characterized in that it further comprises: a second receiver comprising an inner receiver coil and an outer receiver coil configured to sense signals in the second spectrum, the second receiver configured to be minimum-coupled to the second electromagnetic transmitter, wherein the transmitter coil of the second electromagnetic transmitter is disposed between the inner receiver coil and the outer receiver coil of the second receiver ; and a control portion configured to: control the first electromagnetic transmitter to transmit the first waveform in the first spectrum; control the second electromagnetic transmitter to transmit the second waveform in the second spectrum after a specified time delay; receive signals sensed by the first receiver in the first spectrum; and receive signals sensed by the second receiver in the second spectrum, wherein the electromagnetic geophysical exploration system is configured to be airborne. a first electromagnetic transmitter configured to transmit a first waveform in a first spectrum; a first receiver configured to sense signals in the first spectrum; a second electromagnetic transmitter comprising a transmitter coil configured to transmit a second waveform in a second spectrum, the second spectrum having a frequency higher than a frequency of the first spectrum; characterized in that it further comprises: a second receiver comprising an inner receiver coil and an outer receiver coil configured to sense signals in the second spectrum, the second receiver configured to be minimum-coupled to the second electromagnetic transmitter, wherein the transmitter coil of the second electromagnetic transmitter is disposed between the inner receiver coil and the outer receiver coil of the second receiver ; and a control portion configured to: control the first electromagnetic transmitter to transmit the first waveform in the first spectrum; control the second electromagnetic transmitter to transmit the second waveform in the second spectrum after a specified time delay; receive signals sensed by the first receiver in the first spectrum; and receive signals sensed by the second receiver in the second spectrum, wherein the electromagnetic geophysical exploration system is configured to be airborne. a second receiver comprising an inner receiver coil and an outer receiver coil configured to sense signals in the second spectrum, the second receiver configured to be minimum-coupled to the second electromagnetic transmitter, wherein the transmitter coil of the second electromagnetic transmitter is disposed between the inner receiver coil and the outer receiver coil of the second receiver ; and a control portion configured to: control the first electromagnetic transmitter to transmit the first waveform in the first spectrum; control the second electromagnetic transmitter to transmit the second waveform in the second spectrum after a specified time delay; receive signals sensed by the first receiver in the first spectrum; and receive signals sensed by the second receiver in the second spectrum, control the first electromagnetic transmitter to transmit the first waveform in the first spectrum; control the second electromagnetic transmitter to transmit the second waveform in the second spectrum after a specified time delay; receive signals sensed by the first receiver in the first spectrum; and receive signals sensed by the second receiver in the second spectrum, wherein the electromagnetic geophysical exploration system is configured to be airborne. <EOS>