Browsing by Author "Colpitts, Bruce G."

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    A Software Defined Radio Implementation of Direct Sequence Spread Spectrum Harmonic Radar
    (University of New Brunswick, 2022-06) Kozma, Nicholas; Colpitts, Bruce G.
    Proposed is a harmonic radar system back end that makes use of an off the shelf software defined radio to yield a low-form factor and light weight transceiver. This module, composed of the USRP b200 mini software defined radio and the Raspberry Pi 4 computer, forms a flexible test bed for harmonic radar waveform research and testing. Using the transceiver module a variety of direct sequence spread spectrum waveforms were used to detect a tag with the intention of testing the system and finding the most favorable sequence of the proposed options. Although an SDR is unlikely to outperform a custom transceiver optimized for a given application, it has been found that they make a suitable low cost alternative working best with coded radar waveforms.
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    An Extra Low-mass Harmonic Radar Transponder for Insect Tracking Applications
    (IEEE, 2023-06-05) Ala, Ramin; Rouse, Chris D.; Colpitts, Bruce G.
    The design, construction, and performance of a harmonic radar transponder with a total mass of less than 500 μg is presented. The transponder is intended for insect tracking applications and consists of very fine wire and a small Schottky diode. It is designed for fundamental and harmonic frequencies of 10 GHz and 20 GHz, respectively. Compared to existing harmonic radar transponders, this transponder is easy to construct because the loop inductor can be implemented with a simple bend in the dipole conductor without degrading performance. Through careful design optimization, the conversion loss of the transponder is not impacted by the measures taken to minimize its mass. The expected harmonic power versus the transmitted power is estimated based on the link analysis between the transmitter and receiver of the radar, with the link analysis itself being performed via calculation, harmonic balance simulation, and full-wave simulation. The link analysis simulation predicted a received power of -66.4 dBm for a transmitted power of +22 dBm and a range of 2.4 m. The measured received power level at the harmonic frequency, obtained from the broadside of the transponder in an anechoic test chamber, is approximately -70 dBm, which agrees well with the link analysis. Simulated and measured transponder radiation patterns are also compared and show good agreement. Low-mass transponders such as this enable tracking of smaller insects without reducing their lifespan or compromising their ability to fly at natural altitudes and ranges.