Radar to keep track of insects

Press, 1 August 1986, Page 21

Radar to keep track of insects

The need to monitor airborne insect density and provide up-to the-minute information on movements of insects of agricultural importance has led to the development of a fully automatic remote sensing system which uses radar to detect and identify individual insect targets, reports the London Press Service.

The radar, produced by the entomology department at Rothamsted Agricultural ExperiStal Station at Harpenden, London, com>>jlses a short

pulse-length transmitter coupled alternatively to one of two parabolic antenna systems. The antenna assemblies are driven by a computer to produce vertically directed, conically scanned beams within which the electric polarisation of the transmitted pulse can be rotated. As insects fly through the radar beams at heights between 12.5 and 250 metres, the return echoes are detected and processed in real time using a highspeed, multi-nurpose computer. From measurements of the am-

plitude and phase of the return echo, the computer calculates the target insect’s velocity, height of flight, body weight, shape and orientation. These data are then stored for subsequent transmission over the telephone to a remote central computer. Ultimately, the success of the system will depend upon the degree to which the target signatures can classified as specific to insect types. This is a new subject area which is termed "Radar Taxonomyf” The key to

identification is the accurate measurement of the microwave scattering properties of the various insect species likely to be detected by the radar. Preliminary laboratory measurements have already been made on a number 'of insect species, the results agreeing with theoretical predictions.

Over the next few years, several fully automatic, computercontrolled insect radars will be operated at selected sites in Britain. A-