Journal of Geo-information Science >
Development of Ka-band Miniature Synthetic Aperture Radar based on UAV
Received date: 2018-09-10
Request revised date: 2019-03-18
Online published: 2019-04-24
Supported by
National Natural Science Foundation of China, No.61471340
National Key Research and Development Program of China, No.2017YFB0503001
Copyright
Unmanned Aerial Vechicle (UAV) is widely used in military investigation and attack, land and resources survey, disaster monitoring and other fields because of its advantages such as long stay time and easy maintenance. Synthetic aperture radar (SAR) is a kind of two-dimensional imaging radar, which can obtain radar images similar to optical images. It has the advantages of all-weather, high resolution, wide detection range and so on. It is one of the important loads of UAV. However, due to the relatively small space and load capacity of UAV, radar load must be small volume, light weight and low power consumption. Ka-band electromagnetic wave signal has the characteristics of short wavelength, wide bandwidth and small size of key microwave devices. It is suitable for high resolution miniature radar load. In 2015, the Institute of Electronics, Chinese Academy of Sciences, developed a kind of high resolution Ka-band synthetic aperture radar for small or medium UAV. The performance of the SAR was verified by flight test. In this paper, the key technologies of Ka-band SAR radar system are studied. The design scheme of radar system and key modules, the parameter of each working mode and real-time imaging algorithm are introduced. The radar weight is less than 10 Kg, and the peak power consumption is less than 100 W. It is suitable for small or light UAV. The high-resolution flight images obtained by the radar on light flight platform are displayed, and the performance of the images are analyzed. The experimental results show that the Ka-band SAR system can generate clear radar image and meets the design requirements. For example, the image resolution is better than 0.2 m and the detection distance is greater than 10 km..The rapid progress of microwave device technology represented by solid-state high power amplifier is the foundation of the success of this project. The project is a new attempt to develop Ka-band SAR and apply it to UAV. It also makes a useful exploration for the further development of Ka-band synthetic aperture radar and has important application value. The development of small Ka-band synthetic aperture radar in the future depends on the maturity of semiconductor technology and the improvement of the performance of Ka-band microwave devices. On the other hand, it also depends on the research of new style SAR which has high duty cycle and pulse agility, which can improve the average power of radar and solve the problem of ambiguity of detection range.
Key words: UAV; SAR; Ka-band; millimeter wave; radar Image; chirp-scaling algorithm
ZHANG Qi , ZHANG Lei , GUO Jundong , HU Jianmin . Development of Ka-band Miniature Synthetic Aperture Radar based on UAV[J]. Journal of Geo-information Science, 2019 , 21(4) : 524 -531 . DOI: 10.12082/dqxxkx.2019.180453
Tab. 1 Frequency division of electromagnetic wave表1 常用的电磁波频带划分 |
波段符号 | 标称频率/GHz | 波长范围/mm | 波段符号 | 标称频率/GNz | 波长范围/mm |
---|---|---|---|---|---|
UHF | 0.30~1.12 | 1000.0~267.9 | Ka | 26.5~40.0 | 11.3~7.5 |
L | 1.12~1.70 | 267.9~176.5 | Q | 30.0~50.0 | 10.0~6.0 |
LS | 1.70~2.60 | 176.5~115.4 | U | 40.0~60.0 | 7.5~5.0 |
S | 2.60~3.95 | 115.4~75.9 | M | 50.0~75.0 | 6.0~4.0 |
C | 3.95~5.85 | 75.9~51.3 | E | 60.0~90.0 | 5.0~3.3 |
XC | 5.85~8.20 | 51.3~36.6 | F | 90.0~140.0 | 3.3~2.1 |
X | 8.20~12.4 | 36.6~24.2 | G | 140.0~220.0 | 2.1~1.4 |
Ku | 12.4~18.0 | 24.2~16.7 | R | 220.0~325.0 | 1.4~0.9 |
K | 18.0~26.5 | 16.7~11.3 |
Fig. 1 Work for each mode of SAR图1 合成孔径雷达工作模式示意 |
Tab. 2 Performance for each mode of SAR表2 合成孔径雷达各模式设计指标 |
` | 极化 | 分辨率/m | 测绘带宽/km | 距离/km | 供电/V | 功耗/W | 重量/kg | |
---|---|---|---|---|---|---|---|---|
垂直极化 | 聚束 | 0.3 | 0.5×0.5 | ≥ 10 | ||||
Ka | 条带 | 0.3 | ≥2 | ≥ 8 | DC24~30 | <100 | <10 | |
1 | ≥4 | ≥ 10 |
Tab. 3 Pass attenuation rate of signal Transmission in different wavelength表3 不同波段信号的大气衰减比较[21] |
X波段 | Ka波段 | W波段 | ||||||
---|---|---|---|---|---|---|---|---|
晴天低空 | 中雨/(4 mm/h) | 晴天低空 | 中雨/(4 mm/h) | 晴天低空 | 中雨/(4 mm/h) | |||
衰减/(dB/km) | 0.02 | 0.30 | 0.24 | 1.00 | 0.80 | 3.00 |
Tab.4 Power Requirement for each mode of SAR表4 合成孔径雷达各模式功率需求 |
工作模式 | 分辨率/m | Rmax/km | Pav/W |
---|---|---|---|
高分辨率条带 | 0.3 | 6 | 1.6 |
低分辨率条带 | 1.0 | 10 | 2 |
聚束模式 | 0.3 | 10 | 3 |
Fig. 2 Overview of SAR图2 合成孔径雷达组成 |
Fig.3 Design of Ka-band module in transceiver unit with Ka band图3 Ka波段收发单元内Ka波段模块设计 |
Fig. 4 Design of IF band module in transceiver unit with Ka band图4 Ka波段收发单元中频模块设计 |
Tab. 5 Cross-range resolution and the diameter of antenna in typical frequency bands表5 典型频段天线尺寸与理论方位向分辨率对比[22] |
频带范围/GHz | 天线口径/mm | 方位向分辨率/m |
---|---|---|
10 | 3046 | 2.132 |
10.67 | 1827 | 1.279 |
35 | 870 | 0.609 |
94 | 324 | 0.227 |
140 | 218 | 0.152 |
220 | 138 | 0.097 |
注:波束宽度0.5°,展宽因子1.4。 |
Fig. 5 Ground control of SAR in UAV图5 地面对无人飞行平台合成孔径雷达的遥控遥测 |
Fig. 6 Process of Image in SAR图6 合成孔径雷达实时图像处理流程 |
Tab. 6 Completion of Ka band SAR表6 Ka波段合成孔径雷达系统完成情况 |
外形(长×宽×高)/mm | 重量/kg | 功耗/W | |
---|---|---|---|
天线 | 300×150×20 | 0.5 | |
功放单元 | 150×150×100 | 1.5 | 16 |
收发单元 | 300×250×250 | 5.2 | 35 |
处理单元 | 250×250×110 | 2.3 | 47 |
系统 | - | 9.5 | 98 |
Tab. 7 Performance of Ka band SAR when flying test表7 Ka波段合成孔径雷达系统飞行试验达到的性能指标 |
工作模式 | 飞行时作用距离/km | 测绘带宽/km | 图像分辨率/m |
---|---|---|---|
高分辨率条带 | 8 | >4 | <0.2 |
低分辨率条带 | 12 | >6 | <0.5 |
聚束 | 10 | 0.5×1.5(方位×距离) | <0.2 |
Fig.7 The high resolution image and its detail show图7 飞行成像试验得到的高分辨率图像及局部细节 |
Fig. 8 Range and azimuth resolutions of point target in high resolution image of Ka band SAR图8 Ka波段合成孔径雷达高分辨率图像内点目标距离向和方位向的分辨率 |
The authors have declared that no competing interests exist.
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