| Metadata | Details |
|---|
| Publication Date | 2023-03-30 |
| Journal | Micromachines |
| Authors | Qi Wang, Yusong Liu, Yue Qin, Hao Guo, Jun Tang |
| Institutions | North University of China |
| Citations | 1 |
| Analysis | Full AI Review Included |
- Core Technology: Developed a passive microwave direction-finding (DF) scheme utilizing diamond Nitrogen-Vacancy (NV) color centers as quantum sensors.
- Detection Mechanism: The system employs the Coherent Population Oscillation (CPO) effect and continuous microwave excitation ODMR, converting spatial microwave intensity and frequency information into measurable fluorescence spectral shifts.
- Performance Metrics: Achieved a minimum detectable microwave intensity resolution of -20 dBm. The system demonstrated an intensity sensitivity of 108.89 mV/mW.
- Direction-Finding Accuracy: Direction measurement yielded a minimum average angle error of 0.24° (at 5 cm spacing) and a maximum angle error of 0.48° within the ¹15° measurement range.
- Signal Processing: Stability was enhanced using a first-order differential operation on the ODMR spectral curve, followed by a PID frequency locking system (KP=120, KI=90, KD=180) to dynamically measure microwave intensity.
- Direction Calculation: The unknown microwave source direction was calculated using the Weighted Global Least Squares (WGLS) method applied to a five-point cross-position intensity measurement matrix.
- System Advantages: The scheme offers a simple system structure, small equipment size, low system power consumption, and low requirements for information processing capability compared to traditional electronic DF methods.
| Parameter | Value | Unit | Context |
|---|
| Sensor Material | Type Ib Diamond | N/A | 1.5 mm x 1.5 mm x 1.5 mm volume |
| Nitrogen Content | < 200 | ppm | After synthesis and treatment |
| NV Zero Field Splitting (D) | 2.87 | GHz | Ground state 3A2 |
| Excitation Wavelength | 532 | nm | Laser source (150 mW) |
| Applied Magnetic Field | 1.5 | mT | Along diamond <111> crystal axis |
| ODMR Spectral Contrast (C) | 6.2 | % | NV color center performance |
| ODMR Linewidth (Îν) | 2 | MHz | Full width at half height |
| Target Microwave Frequency (fLO) | 2.9063 | GHz | Main radiation frequency of array antenna |
| Minimum Detectable Intensity | -20 | dBm | System resolution limit |
| Intensity Sensitivity | 108.89 | mV/mW | Measured feedback curve relationship |
| Emission Power Range (P) | 12 to 26 | dBm | Analog microwave source power |
| Angle Measurement Range (θ) | ¹15 | ° | Measurement position range |
| Minimum Average Angle Error | 0.24 | ° | Achieved at 5 cm spacing distance |
| Maximum Angle Error | 0.48 | ° | Under different emission powers |
| PID Parameters (KP, KI, KD) | 120, 90, 180 | N/A | Optimal closed-loop locking parameters |
| Array Antenna Gain (Simulated) | 18.15 | dB | Main radiation direction |
- NV Center Creation: Used Type Ib diamond (N < 200 ppm) synthesized at high temperature/pressure, followed by 4 hours of electron irradiation and 2.5 hours of high-temperature annealing.
- Spin Initialization and Tuning: A 532 nm laser was used for optical initialization. A 1.5 mT magnetic field was applied along the <111> crystal axis to regulate the ODMR spectral peak position via Zeeman splitting.
- Microwave Excitation and CPO: A continuous frequency-modulated (FM) microwave was applied. The dual-channel microwave frequency was set to resonate with the NV energy level, utilizing the Coherent Population Oscillation (CPO) effect to convert microwave intensity changes into spectral âhole burningâ depth.
- Signal Differentiation: The ODMR spectral curve under CPO influence was processed using a first-order differential operation (implemented on an FPGA) to transform intensity changes into a shift (Îf) of the zero-crossing position, improving information extraction stability.
- Closed-Loop Intensity Measurement: A Proportional-Integral-Differential (PID) frequency locking system was used to lock the zero position of the differential curve. The feedback output required to maintain the lock was used as the measured microwave intensity (AV).
- Spatial Sampling: Microwave intensity was measured at five cross-positions in a two-dimensional plane (distance Ď = 100 cm to 150 cm) to form an observation matrix.
- Direction Calculation: The relative angle of the unknown microwave source was calculated by matching the measured intensity distribution to the known antenna radiation pattern using the Weighted Global Least Squares (WGLS) method, accounting for unequal accuracy in the observation matrix.
- Quantum Sensing and Metrology: Provides a highly sensitive, solid-state platform for measuring microwave fields, electric fields, and magnetic fields in extreme or complex environments.
- Passive Surveillance and Reconnaissance: Ideal for military and civilian applications requiring high concealment, such as detecting and locating RF emitters (e.g., drones, radar) without transmitting any signal.
- Miniaturized RF Detection Systems: The small size and low power consumption inherent to diamond NV sensors enable the development of highly portable and integrated direction-finding equipment.
- Multi-Platform Detection Networks: Suitable for deployment in distributed sensor arrays or multi-platform systems where size, weight, and power (SWaP) constraints are critical.
- Electromagnetic Compatibility (EMC) Testing: Useful for mapping precise microwave field distributions in small spatial regions, aiding in the design and validation of electronic equipment.
View Original Abstract
In this study, we established a passive direction-finding scheme based on microwave power measurement: Microwave intensity was detected using microwave-frequency proportion integration differentiation control and coherent population oscillation effect converting the change in microwave resonance peak intensity into a shift of the microwave frequency spectrum, for which the minimum microwave intensity resolution was â20 dBm. The direction angle of the microwave source was calculated using the weighted global least squares method of microwave field distribution. This lay in the 12~26 dBm microwave emission intensity range, and the measurement position was in the range of (â15°~15°). The average angle error of the angle measurement was 0.24°, and the maximum angle error was 0.48°. In this study, we established a microwave passive direction-finding scheme based on quantum precision sensing, which measures the microwave frequency, intensity, and angle in a small space and has a simple system structure, small equipment size, and low system power consumption. In this study, we provide a basis for the future application of quantum sensors in microwave direction measurements.
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