In the last 5 years, advances in receiver suspension and receiver construction have made airborne electromagnetic low-base frequency operation possible and greatly improved the ability to explore in conductive environments. We discuss the changes made to the Xcalibur Helitem2, helicopter time domain EM, system to enable low base frequency operation - first at 15/12.5Hz, and then at 7.5/6.25Hz. The transmitter has also been redesigned to now use a square input waveform at 50% duty cycle, with a rapid turn-off. At low base frequencies this results in a long, high powered transmitter pulse that still creates high frequency signal. Various data examples will be shown to illustrate the practical advantages of the system updates. This includes an example from Nevada where various Helitem2 system configurations were flown over a line of ground TDEM data at different heights, as well as a Nickel exploration project.

Open-Access Online Publication: October 30, 2023