#Resolution series

#Resolution series

To beat this limitation, Howell and his colleagues designed a radar waveform that looks like a series of zigzags, with a triangular peak and trough and an additional peak and trough that are truncated so that they include flat segments. Van/ Rocks or mines? A landmine might be indistinguishable from a rock if the radar image has low resolution, as is evident from this photo of a collection of recovered mines. So in order to increase the sensitivity at longer distances, radar users must employ longer pulses and thus sacrifice resolution. This increasing opaqueness limits the depths to which one can probe when including high frequencies. “Almost every material medium becomes more opaque with increasing frequency,” says John Howell, a radar scientist at Chapman University in California. Typically, pulses are shortened by adding in higher-frequency waves, but adding those frequencies has a downside. Reducing a pulse’s length requires increasing its bandwidth, which is the spread of frequencies that add up to make the pulse. To increase a radar’s power to resolve objects that are close to each other, the pulses can be shortened. When there are two objects in the pulses’ path, the device can resolve both objects if it detects two distinct peaks in the reflected radio waves. The device uses the reflected waves to determine the object’s size and distance. Archeologists could also use the new method to find buried artifacts.Ī radar system sends out a series of short radio-wave pulses that may encounter an object and reflect back to the device. The researchers say that their technique could allow detection of landmines buried a few meters underground, far deeper than the few centimeters accessible with current technology. Now researchers have demonstrated a proof of concept for a radar method that can resolve smaller objects at greater depths than was previously possible. The radar devices used to spot landmines have trouble distinguishing features at the depths at which these objects are typically buried, which can lead to false positives and thus wasted time. Ground penetrating radar survey at the Nabataeo-Roman archeological site of Wadi Ramm, Jordan.

Archaeo-Physics LLC, Public domain, via Wikimedia Commons Subterranean study.