A wideband harmonic radar for tracking small wood frogs

Abstract

A wideband harmonic radar for tracking very small wood frogs in a high clutter environment is described. The one watt peak power radar transmitted in the 5.8 GHz ISM band and received in the 12 GHz satellite TV band. By transmitting a 150 MHz bandwidth linear frequency modulated waveform and exploiting the frequency doubling property of the harmonic tag to increase the bandwidth to 300 MHz, a range resolution of 1.6 feet was demonstrated. Furthermore, by resolving transmitter leakage and multipath, and by coherently integrating the tag return, the wideband harmonic radar sensitivity was improved by 20 dB over a comparable CW harmonic radar.

A Review: Recent Progress in the Design and Development of Nonlinear Radars

“…Refs. [30][31][32] discuss the use of harmonic radar to track amphibians' behavior in a clutter-rich environment. The radar in [30,31] was operated in a 5.8 GHz ISM band for transmission and a 12 GHz satellite TV band for the reception for the nonlinear response.…”

Two-Tone Excited Hybrid-Coupler-Based Intermodulation Generator for High-Isolation Wireless Sensing Applications

“…Furthermore, with an increase of the incident power, the phase differences between the intermodulation of V'cou and V'dir decrease incessantly, whose trend approaches +90° (+i). With comparison of (6) and (7), only a condition under the term of 12a3V 3 IN << term of 25a5V 5 IN can explain such ADS simulation results in Fig. 3b.…”

“…3b, it can be noticed that 3 rd harmonic generated from D1 and D2 at P2 and P3 respectively keeps equal, while its phase differences maintain approximately -90° (-i). Henceforth, only the term of a3V 3 IN >> the term of 2a5V 5 IN in (6) and (7) can explain the equal power magnitudes and -90° (-i) phase differences of the 3 rd harmonics at P2 and P3 of hybrid coupler. Similarly, the intermodulation generations from D1 and D2 can also be evaluated with an identical incident power, which is given in Fig.…”

“…When a base station interrogates the harmonic transponder at the fundamental frequency (ω0), the 2 nd harmonics (2ω0) are accordingly generated and backscattered, which can then be captured and demodulated by the base station for atmospheric physics data retrieves. On account of its high robustness to the environmental clutter interference, 2 nd -harmonic transponders have been successfully employed into various scenarios, e.g., the foraging range of bumble-bees research [2], wood frogs tracking [3], avalanche victim searching [4], and cracked wall monitoring [5], and etc.…”

Harmonic Synthetic Aperture Radar Processing

“…This was a single-tone system receiving twice the transmitting frequency. Harmonic radar has also been used to track insects and small animals [3]- [7]. Other known applications are, for example, in problems related to detection of vital signs [8]- [10], temperature sensing [11], [12] and detection of radio-frequency (RF) electronics [13].…”