ERA Technology has recently completed a major research project to develop a hand-held microwave detector to aid screening procedures at security checkpoints. The prototype detector has been successfully demonstrated to locate non-metallic weapons, materials and surrogate explosives concealed below clothing on humans.

The development project, funded by the ERA Foundation, involved a series of fundamental measurements to understand the RF / human body interactions in the 10 - 40GHz range and the subsequent design and construction of a number of prototype devices to prove the viability of the detector concept chosen.

The target specification for the detector included the following:
	detection of non-metallic banned substances or devices
	ability to be manufactured in volume at a low unit cost
	sufficient sensitivity to detect 200g sheets of explosive
	sufficient sensitivity to detect ceramic or plastic weapons

The prototype detector is essentially a microwave radiometer with its own microwave source for illuminating a target area of about 20mm x 10mm.Two receivers eliminate the variations due to changes in the local microwave environment and increase the differentiation between signals received from hidden materials and the human body. As the detector is scanned over the subject, any concealed objects cause a change in the reflected microwave energy which in turn, cause a change in the instrument's audio output, alerting the user.

The prototype system has consistently detected ceramic and dielectric target items concealed under clothing on the human body, with the target object signal many times greater than the variation noted in scanning over the body. The next stage of development will aim to improve the detector capability by incorporating a transmit antenna with distributed radiation sources. This will also reduce the requirement to hold the detector square to the surface under inspection and effectively de-skill the search process.

The final prototype could also have a metal-detector facility incorporated, which would form the basis of a production design with the following performance features:
	frequency range 28-40GHz
	transmit power 1µW
	receiver noise figure 4.8dB
	receiver gain 30dB
	antenna lens diameter 150mm
	receive spot size 10mm (two off adjacent)
	depth of focus 90mm to 140mm

ERA now seeks a partner to help finalise the production design and take the detector into full manufacture. David Daniels, Head of Sensor Systems at ERA, explained: "The detector has proved extremely effective at locating non-metallic weapons and surrogate explosives.The prototype unit is fully functional and available for demonstrations.We now need a manufacturing partner to help complete the final development of the production detector for use by security authorities around the world."

ERA is also actively investigating a range of other novel microwave techniques for security applications.

For further information contact: david.daniels@era.co.uk