Development of harmonic radar for insect detection

Abstract

Harmonic radar technology has been researched and developed for studying the foraging behaviour of insects such as honey bees in order to study their decline in the ecosystem. The traditional radar fails to detect the bees due to their very low radar cross-section caused by their small sizes. The harmonic radar overcomes this limitation by tagging the insects with a harmonic tag consisting of a dipole and a diode. The tag utilizes the nonlinearity property of the diode to convert the carrier frequency of the transmitted signal received by the dipole to its harmonic components, which the dipole re-transmits to the radar. The radar detects the tag on the bee from the second harmonic in the received signal at the radar. This work presents the development of a working prototype of a first generation harmonic radar system to detect the presence of the insect tag at 2.5/5GHz. The thesis discusses the design methodology undertaken to build the radar using offthe-shelf components available in the institute lab. Based on empirical tests on the tag, we estimate the radar probability of detection and probability of false alarms as 88% and 0.3% respectively. The maximum detectable range for a monostatic configuration of the radar is 3.84 m.