Miniaturization of a Low Power Harmonic Radar for UAV use

Abstract

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.

Popular Abstract

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.

• author: Aljaser, Saleh
• supervisor: Anders J Johansson
• organization: Department of Electrical and Information Technology
• course: EITM02 20191
• year: 2019
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: Harmonic, Radar, Insects, Tracking, Detection, UAV, FMCW, Small, Low Power, Wireless, Communications
• report number: LU/LTH-EIT 2019-715
• language: English
• id: 8990574
• date added to LUP: 2019-07-12 14:01:06
• date last changed: 2019-07-12 14:01:06