Miniaturization of a Low Power Harmonic Radar for UAV use

The aim with this Master thesis work is to design, build and test a small size, light weight and low power consumption harmonic radar system that will be installed in a flying drone for the purpose of tracking and localizing tagged Bogong moths near their aestivation caves and crevices in Australia during summer. A FMCW harmonic radar is proposed, it comprises a radar transmitter, receiver and a signal processor. The challenges of the design are to make the system small and light enough to be carried by the drone and to keep power consumption as low as possible to at least complete an entire search mission with one battery charge. The investigations during the thesis cover link budget analyses for different design options, operating frequency selection, waveform design, system simulations and components selection. The moths are tagged with a special adhesive tag which is small so it does not disrupt the insect movement, the small size and low reflected power of the tag limits the radar detection range and the radar design is optimized to improve range measurement by proper selection of components and proper design of the radar waveform.In Australia nearly two billion Bogong moth migrate twice every year for hundreds of kilometers. They migrate in spring from different parts of Australia to the Australian Alps looking for cold weather, they stay in the mountains for four months during summer. They get back in the beginning of autumn to their original places. When they reach the cold mountains in the south they start their aestivation period gathering in large numbers on the walls of the caves on the mountains sides and under tree trunks, there are about 17000 moths per square meter on these walls. Finding Bogong moths is very important for researchers to study the way that they navigate during their night time migration. However, finding them is challenging and can be only by luck since it requires climbing the mountains sides and searching thoroughly in all crevices and small openings in the rocks [5]. Researcher makes use of special pieces of equipment to search and locate the moths under the rock, tree trunks and inside the caves. One way to do so is by using radars. A radar is a radio transceiver system that transmits a special electromagnetic signal and then listens to the reflections of that signal from the surrounding environment. It measures the time difference between the transmitted and reflected signals to calculate the objects ranges. Radars have been used before to detect different flying and ground insects and found to be effective, however there are several challenges of detecting small insects since radars relay on the reflected signal power from targets of interest, and the smaller the target is the weaker the reflected power to the radar, one other problem is the reflections from other unwanted objects around the target which can mask the target reflections, they are called clutter. In this thesis we attempt to investigate the use of radars to detect Bogong moths. The idea is to use special type of radars called Harmonic Radars that use the fundamental signal frequency for transmission and the second signal harmonic for reception to get some sort of clutter immunity and highlight the Bogong moth by tagging it with a special adhesive tag. The system is then designed, built and tested as a proof of concept for the Bogong moth detection