A High-Range-Accuracy and High-Sensitivity Harmonic Radar Using Pulse Pseudorandom Code for Bee Searching

Abstract

This paper presents a 9.4/18.8-GHz harmonic radar to investigate the behavior of bees with colony collapse disorder. The challenges of using harmonic radar for bee searching include the requirements of high range accuracy and high sensitivity. A new harmonic radar using the pseudorandom code positioning technique to simultaneously achieve high range accuracy and high sensitivity is proposed. This study also proposes a new method to cancel the local leakage to further improve sensitivity. To realize the transponder, a compact antenna is designed using the topology characteristics of the composite right/left-handed transmission-line concept. The measured sensitivity of the transceiver is 120 dBm, which is 27 dB lower than the noise level. Field testing results demonstrate a 60-m detection range within 1-m distance error with 1.75-W transmitting power. The significant improvement of the sensitivity and the range accuracy reveal the advantages of applying the code-positioning technique to the harmonic radar.

A wideband harmonic radar for tracking small wood frogs

“…None was built, but the problem of requiring a transmitter devoid of harmonics was mentioned. Tsai et al [4] described a harmonic radar using a phase coded pseudo-random noise (PN) waveform with a 25 MHz chip rate. A phase coded PN sequence does not benefit from the frequency doubling property of a harmonic tag.…”

“…However, the legality and safety of operating such a powerful marine radar on land are questionable. Recently, Tsai et al [4] described a low-powered, two watt, X-band stationary harmonic radar with a detection range of 60 meters in free space.…”

Concurrent Vital Sign and Position Sensing of Multiple Individuals Using Self-Injection-Locked Tags and Injection-Locked I/Q Receivers With Arctangent Demodulation

“…Moreover, the TDOA between the and receiver is proportional to the phase difference between and , which is described by (16) where and are the distance from the tag to the and receiver, respectively. that are emitted from the tag with unknown position, hyperbolas are plotted using the following equations:…”

“…In an RTOF system, the receiving units are replaced with ranging radars, such as pulsed radars [13] or frequency-modulated continuous wave (FMCW) radars [14]. Moreover, the target carries a transponder that often utilizes passive frequency doubler [13]- [16] to respond to the interrogating radar signal, and the round-trip propagation delay is measured to determine the position of the target. However, the propagation loss leads to a trade-off between sensing range and radar transmitting power.…”

Harmonic Transponders: Performance and Challenges

“…Depending on the application and technology, the used fundamental frequency varies. In RECCO avalanche detectors [7], a fundamental frequency of 0.917 GHz is used, whereas other technologies [8,9] operate using maritime radar frequencies (f 0 ≈ 9.4 GHz) or at the ISM band (f 0 being, e.g., 2.45, 5.8, or 5.9 GHz [10][11][12]). One particular challenge for practical, commercial harmonic transponder applications and their widespread use is finding a suitable frequency pair that complies with existing frequency allocations simultaneously at both frequencies.…”