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Every ground penetrating radar survey is governed by one unavoidable trade-off: lower frequencies see deeper but resolve less detail, while higher frequencies sharpen the image but lose depth. For airborne GPR on platforms like the DJI M300 RTK, that choice is locked in at the antenna, so it pays to match frequency to both your target depth and the ground you are flying over. This guide compares the three ZondAero options Measur supplies and shows how soil type and moisture shift the result.
The depth-versus-resolution trade-off
GPR sends an electromagnetic pulse into the ground and records the reflections from boundaries between materials with different dielectric properties. The center frequency of the antenna sets the character of that pulse. A low-frequency, long-wavelength pulse carries more energy into the subsurface and is absorbed more slowly, so it reaches deeper targets. A high-frequency, short-wavelength pulse resolves thinner layers and smaller objects, but attenuates quickly and rarely sees more than a couple of metres.
You cannot have maximum depth and maximum resolution from the same antenna. The practical job of antenna selection is to choose the highest frequency that still reaches your deepest target of interest, because that combination gives you the sharpest possible image at the depth you actually need.
The three ZondAero antennas compared
The ZondAero ground penetrating radar family spans that whole trade-off, from a deep-looking low-frequency dipole to a high-resolution 1000 MHz shielded unit. All three are designed for medium drones such as the DJI M300 RTK or M600/M600 Pro and draw power from the drone's main battery, with data written to standard SEGY (.sgy) files carrying geotagged traces.
| Spec | ZondAero LF | ZondAero 500 | ZondAero 1000 |
|---|---|---|---|
| Center frequency | 100 / 150 / 300 MHz (custom 50–400 MHz) | 500 MHz | 1000 MHz |
| Antenna type | Single-channel, unshielded dipole | Single-channel, shielded | Single-channel, shielded |
| Operating bandwidth | 38–150 / 75–300 / 150–600 MHz (-12 dB) | 200–900 MHz (-12 dB) | 600–1300 MHz (-6 dB) |
| Stated depth | Up to 12 m (permittivity 5, attenuation up to 5 dB/m) | Up to 4 m in average normal soil (100 ns range) | Up to 2 m depending on ground properties |
| Scan rate | Up to 2,500 scans/s (with hardware stacking) | 50 scans/s | 50 scans/s |
| Airborne weight | 0.8 kg controller + 0.1–0.4 kg antenna | 2.1 kg (without mounting kit) | 1.7 kg (without mounting kit) |
ZondAero LF: maximum penetration
The ZondAero LF ships with three interchangeable dipole sets calibrated to 300, 150 and 100 MHz, with custom frequencies down to 50 MHz available on request. In favourable ground it is rated to reach up to 12 metres, making it the tool for bedrock mapping, deep geological boundaries, peat and overburden thickness, and groundwater investigations. As an unshielded dipole it is extremely light, the controller is just 0.8 kg, but it is also more exposed to airborne reflections, so flight height and clearance matter. Real Time Sampling with high hardware stacking helps keep the deep, low-amplitude returns clean.
ZondAero 500: the general-purpose middle ground
The ZondAero 500 is the balanced choice for most engineering and environmental work, reaching up to roughly 4 metres in average soil while still resolving useful structural detail. Its shielded antenna suppresses above-ground noise, which is valuable in cluttered survey environments. Typical jobs include utility corridors, shallow stratigraphy, void and sinkhole screening, and archaeology where targets sit within the first few metres.
ZondAero 1000: maximum resolution
The ZondAero 1000 trades depth for detail, with a wide 600–1300 MHz band and penetration to around 2 metres depending on the ground. It is the antenna for thin-layer work, near-surface mapping, dense reinforcement or shallow utilities, and any survey where separating closely spaced reflectors matters more than reaching depth. At 1.7 kg airborne it is also the lightest shielded unit in the range.
How soil type and moisture change the answer
The depth figures above are not fixed. GPR performance is dictated by the electrical properties of the ground, principally its relative dielectric permittivity and its attenuation, and both are driven heavily by moisture and clay content.
- Dry sand and gravel are low-loss and let the signal travel furthest. Stated depths are realistic here, and you can often run a higher frequency than expected.
- Clay and silt are the hardest materials for GPR. They are conductive and attenuate the pulse rapidly, sometimes halving usable depth, which pushes you toward the lower-frequency LF antenna even for shallow targets.
- Moisture raises permittivity, slowing the wave and increasing attenuation. Saturated ground after rain can sharply reduce depth, so survey timing affects which antenna performs.
- Mixed and layered ground often benefits from carrying two frequencies and flying the site twice to combine deep context with shallow detail.
The practical rule: in conductive, wet or clay-rich ground, drop to a lower frequency to keep any usable depth at all. In dry, sandy, resistive ground you can push the frequency up and gain resolution for free.
Choosing and integrating your antenna
Start from your deepest target, apply a realistic depth penalty for your soil and moisture conditions, then pick the highest frequency that still reaches it. When deep and shallow targets coexist, plan for two passes rather than compromising on one antenna. For the integration side, including positioning, flight planning and payload control, see our pillar guide to advanced drone surveying with SPH Engineering and the focused walkthrough on airborne GPR with ZondAero. Complex multi-sensor builds are covered in our note on the role of SkyHub in integrating drone payloads. If your work also extends over water or to gas detection, our guides on drone bathymetry with the Surveyor 240-16 MBES and methane detection with the Laser Falcon round out the airborne survey toolkit. When you have narrowed the choice, request a quote and our team will confirm the right complete set for your platform.
Key Takeaways
- Lower frequencies penetrate deeper but resolve less; higher frequencies sharpen detail but lose depth.
- ZondAero LF (100/150/300 MHz) reaches up to 12 m in favourable ground for bedrock and deep geology.
- ZondAero 500 MHz is the general-purpose choice, reaching up to about 4 m in average soil.
- ZondAero 1000 MHz gives maximum resolution to roughly 2 m for thin-layer and near-surface targets.
- Clay, silt and moisture sharply reduce usable depth and push you toward lower frequencies.
- Dry sand and gravel are low-loss, letting you run higher frequencies for more detail.
- For sites with both deep and shallow targets, fly two passes with two frequencies.
