The investigation of millimetre wave optical harmonic transponders and radar for monitoring small insects

The paper investigates the use of millimetre wave optical harmonic transponders for tracking small insects. Their small dimensions (5.15mm × 2.91mm), low profile, and low weight (~10mg) make them suitable for monitoring small insects. It provides 5dB and 3dB improvement in conversion gain under no illumination when illuminated by red laser without and with 0.9OD neutral density filter respectively. Its associated low power harmonic radar can be portable due to the small size of the millimetre wave components. So far, the prototype radar operating in CW mode has detected optical transponders up to a range of 1m. The detection range, and range resolution can be improved by increasing the radar antenna gains and improving the receiver noise floor by introducing a frequency modulation technique and reducing the receiver bandwidth.