Location: Application Technology ResearchTitle: Capability of patch antennas in a portable harmonic radar system to track insects Author
Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/2011
Publication Date: 5/24/2011
Publication URL: http://hdl.handle.net/10113/50053
Citation: Zhu, H., Psychoudakis, D., Brazee, R.D., Thistle, H.W., Volakis, J.L. 2011. Capability of patch antennas in a portable harmonic radar system to track insects. Transactions of the ASABE. 54(1):355-362. Interpretive Summary: Every year insect pests cause substantial economic losses to agricultural and forest crops. To develop more effective pest control measures and limit their spread, data on the dispersal and behavioral patterns of these insects are needed to help develop control and management strategies. This research investigated the performance of our newly developed entomological harmonic radar tracking systems for a potential technology to study behavior, population dynamics and movement of insects. The system is miniaturized by using patch antenna transponders to improve dipole or monopole antenna transponders for tracking insects in the area where sources of electricity or transportation vehicles are unavailable. The system offers a unique combination of portability, low power and small tag design to improve harmonic conversion efficiency. It would have a great potential to be used for tracking agricultural and forest insects and even animals when the technology of the engineering process for fabrication of miniaturized patch antennas is achieved in the future.
Technical Abstract: Monitoring technologies are needed to track insects and gain a better understanding of their behavior, population, migration and movement. A portable microwave harmonic-radar tracking system that utilizes antenna miniaturization techniques was investigated to achieve this goal. The system mainly consists of a compact radar unit, a hand-held transmitter/receiver (Tx/Rx) patch antenna array panel, and a passive radio frequency (RF) transponder. The system transmits a signal at a 5.882 GHz frequency and receives returned signals at the 11.764 GHz band. The RF transponder to be mounted on insects is 9.63 mm by 9.63 mm flat plane weighing 6 mg. Tests were conducted to optimize horizontal and vertical tracking ranges of the system by measurement of radio frequency signal strength from the transponder in open terrain, inside tree canopies and underground at different tracking angles. In open terrain, a directional tracking range of over 60 m was achieved. However, obstructions from tree canopies and the high water content of leaves severely weakened the microwave signal strength and restricted the tracking range below 20 m. To obtain maximum signal strength, the Tx/Rx antenna panel and the transponder must be in a mutually clear line of sight and their angles must be maintained within a 10 degree range. However, the use of harmonic radar technology to develop a portable tracking system with a small insect-borne transponder currently poses insurmountable challenges for antenna design due to the very stringent requirements to accommodate the tracking range, the transponder size and mass, and methods used to attach transponders to insects.