The semiairborne transient electromagnetic method (SATEM) is a geophysical method that combines the advantages of high-power ground-based transmitting and efficient airborne observation. In recent years, the threshold for SATEM application has been significantly reduced through the integration of multirotor unmanned aerial vehicles and systems obtained by the simple redevelopment of existing ground-based systems. However, it is still difficult to obtain good detection results with such systems for the following specific reasons: in terms of system design, there is a lack of method for estimating the key parameters of the system, resulting in the designed system being unable to effectively meet the requirements of the SATEM method and observation scenarios; in terms of technology, there is a lack of effective means of ensuring a high signal-to-noise ratio (high-current transmitting and effective suppression of major external noise) while meeting the demand for distortion-free observation. In response to these issues, a system bandwidth estimation method based on the analysis of information-carrying capacity is developed. Based on this, solutions for large current and fast turn-off transmitter and for overcoming major external noise are provided. Through a survey located in a karst landform area, the overall application performance of the system is discussed based on the inversion results.

In recent years, unmanned aerial vehicles (UAVs) have increasingly become carrying platforms for Earth observation systems equipped with optical, microwave, and other types of sensors, primarily enabling high-resolution observations of above-ground targets. With the development of geophysical methods, bulky instruments originally designed for deep subsurface detection have been progressively miniaturized and made more lightweight, allowing their integration with civilian UAVs and opening new technological avenues for subsurface investigation. We have developed a semi-airborne transient electromagnetic system based on a UAV that is capable of simultaneously obtaining underground resistivity and polarization rate parameters. A survey was conducted over the M’sesa mining area in the Democratic Republic of the Congo. This is a mine pit that has been abandoned for over 50 years and has been flooded to form a lake, making it difficult to detect its deep mineralization potential using traditional ground-based methods. The results clearly delineate the spatial distribution of the Shangoluwe–M’sesa compressional fault and reveal a deep low-resistivity and high-chargeability zone, which provides clues for the exploration of deep deposits. This study will be of significant importance for accelerating the promotion and application of UAV-based semi-airborne electromagnetic exploration technologies.

As supply risks for cobalt and other critical metals increase, detecting concealed orebodies in mature mining districts has become increasingly important for resource renewal. The Ksignal area, located on the margin of the Kambove mining district in the Democratic Republic of the Congo, lies near the M’sesa-Shangolowe structural system and exhibits copper geochemical anomalies. Together with the district’s position in the core of the Central African Copperbelt, these features indicate strong potential for concealed copper–cobalt mineralization. To investigate this potential, we conducted a semi-airborne transient electromagnetic survey in the Ksignal area. Because induced polarization effects can distort transient electromagnetic responses and complicate resistivity interpretation, we account for these effects and jointly estimate resistivity and chargeability from the observed data. The resulting resistivity–chargeability framework reveals an electrical discontinuity, which we interpret as an electrical structural interface in the Ksignal area. By integrating this inferred interface with borehole constraints and copper geochemical anomalies, we identify and interpret composite anomalies related to concealed mineralization. The results delineate a coherent candidate zone east of the inferred electrical structural interface, trending from near north–south to north-northwest and partly coinciding with the copper geochemical anomaly. This work provides geophysical evidence for deep and peripheral exploration in the Kambove mining district and supports the development of multiparameter target-delineation workflows for brownfield exploration.