Product Category
Electromagnetic (EM) Systems
Frequency-domain electromagnetic instruments from Geonics, DUALEM, and GSSI, for terrain conductivity mapping, buried metal and UXO detection, and salinity or contaminant plume mapping. Available New, Refurbished, Absolute Certified, or Surplus.
What is a Geophysical EM System?
Frequency-domain electromagnetic (FDEM) instruments induce a time-varying magnetic field into the ground from a transmitter coil, which in turn induces eddy currents in any electrically conductive material below — soil and rock of varying conductivity, groundwater with dissolved salts, or buried metal objects. A receiver coil measures the secondary field generated by those eddy currents, and its amplitude and phase relative to the primary field are used to calculate apparent ground conductivity (and, for metal targets, to detect and sometimes classify buried objects).
Measurement Outputs
- In-phase component: Dominated by the response of highly conductive targets such as metal objects — the primary channel used for UXO and buried-metal detection.
- Quadrature component: Proportional (at low induction number) to bulk terrain conductivity, expressed in milliSiemens per meter (mS/m) — the primary channel used for soil/geology and contaminant mapping.
Coil Configurations & Depth of Investigation
Depth of investigation is governed largely by the transmitter-receiver coil spacing and orientation (vertical vs. horizontal dipole mode): small handheld or cart-mounted single-coil systems investigate the near-surface (roughly 0–2 m), while larger fixed-boom or towed-sled systems with wider coil spacing can reach tens of meters. Multi-coil systems (offering several coil-spacing/orientation combinations simultaneously) allow a single pass to build a layered conductivity profile rather than a single bulk value.
Applications
EM survey is widely used for rapid terrain conductivity mapping in precision agriculture (soil salinity, texture zoning) and environmental site characterization (contaminant plume delineation, landfill boundary mapping), as well as for buried metal and UXO screening ahead of construction or remediation work, and for archaeological and geological reconnaissance where the survey area is too large for a slower method such as GPR.
EM System Brands We Supply
| Brand | Origin / Parent | Known For | Typical Application |
|---|---|---|---|
| Geonics | Independent (Canada) | Frequency-domain EM conductivity meters and metal-detection/UXO systems, the long-standing industry-standard EM instrument line | Conductivity mapping, UXO screening |
| DUALEM | Independent (Canada) | Multi-coil EM systems providing several depths of investigation in a single pass | Precision agriculture, environmental |
| GSSI | Independent (USA) | EM profiler systems for utility and conductivity mapping alongside its GPR line | Utility mapping, conductivity survey |
Condition Tiers for EM Equipment
Factory New
Transmitter/receiver console and coil boom direct from the manufacturer, full OEM warranty and factory response certificate.
Refurbished
Coil boom, cabling, and electronics inspected; console function-tested with a known conductivity/metal target before dispatch.
Absolute Certified
In-phase and quadrature response verified against reference conductivity and metal targets on a calibrated test range; calibration certificate issued at handover.
Surplus
Decommissioned or excess survey-company EM units, sold functional and as-is — a cost-effective option for occasional-use programs.
Frequently Asked Questions
What's the difference between EM systems and resistivity/IP systems?
Both measure electrical properties of the ground, but EM systems induce currents inductively (no ground contact needed) and are generally faster to survey with, while resistivity/IP systems inject current directly into the ground through electrodes and generally achieve higher-resolution, more quantitatively invertible subsurface images at the cost of slower setup. EM is often used for rapid reconnaissance, with resistivity/IP follow-up on identified targets of interest.
Can EM systems distinguish buried metal from natural conductive anomalies?
The in-phase response is dominated by highly conductive metal targets, giving EM systems good sensitivity for buried metal and UXO screening, but distinguishing target type (ferrous vs. non-ferrous, size, depth) from a single EM reading has limits — multi-frequency or multi-coil systems and, where needed, follow-up magnetometer or GPR survey improve discrimination. Tell us your screening requirement and we can recommend an appropriate system or combination.
Do refurbished EM systems need the coil boom recalibrated?
Coil geometry (spacing and orientation) is fixed by the boom construction and doesn't drift with age, but electronic gain and phase response can shift over years of field use. Our Refurbished tier includes a functional check against a known target; our Absolute Certified tier goes further, verifying in-phase and quadrature response against calibrated reference targets and issuing a certificate.