Zhang Tianchi, Li Zongxiang, Duan Changjiao, Wang Lihua, Wei Yongli, Li Kejie, Li Xin, Cao Baofeng
State Key Laboratory of NBC Protection for Civilian, Beijing 102205, China.
College of Information and Communication Engineering, Harbin Engineering University, Harbin 150001, China.
Sensors (Basel). 2024 Oct 2;24(19):6406. doi: 10.3390/s24196406.
The Spaceborne Global Lightning Location Network (SGLLN) serves the purpose of identifying transient lightning events occurring beneath the ionosphere, playing a significant role in detecting and warning of disaster weather events. To ensure the effective functioning of the wideband electromagnetic pulse detector, which is a crucial component of the SGLLN, it must be tested and verified with specific signals. However, the inherent randomness and unpredictability of lightning occurrences pose challenges to this requirement. Consequently, a high-power electromagnetic pulse radiation system with a 20 m aperture reflector is designed. This system is capable of emitting nanosecond electromagnetic pulse signals under pre-set spatial and temporal conditions, providing a controlled environment for assessing the detection capabilities of SGLLN. In the design phase, an exponentially TEM feed antenna has been designed firstly based on the principle of high-gain radiation. The feed antenna adopts a pulser-integrated design to mitigate insulation risks, and it is equipped with an asymmetric protective loading to reduce reflected energy by 85.7%. Moreover, an innovative assessment method for gain loss, based on the principle of Love's equivalence, is proposed to quantify the impact of feed antenna on the radiation field. During the experimental phase, a specialized E-field sensor is used in the far-field experiment at a distance of 400 m. The measurements indicate that at this distance, the signal has a peak field strength of 2.2 kV/m, a rise time of 1.9 ns, and a pulse half-width of 2.5 ns. Additionally, the beamwidth in the time domain is less than 10°. At an altitude of 500 km, the spaceborne detector records a signal with a peak field strength of approximately 10 mV/m. Particularly, this signal transformed into a nonlinear frequency-modulated signal in the microsecond range across its frequency spectrum, which is consistent with the law of radio wave propagation in the ionosphere. This study offers a stable and robust radiation source for verifying spaceborne detectors and establishes an empirical foundation for investigating the impact of the ionosphere on signal propagation characteristics.
星载全球闪电定位网络（SGLLN）旨在识别电离层以下发生的瞬态闪电事件，在灾害天气事件的检测和预警中发挥着重要作用。为确保作为SGLLN关键部件的宽带电磁脉冲探测器有效运行，必须用特定信号对其进行测试和验证。然而，闪电发生的固有随机性和不可预测性给这一要求带来了挑战。因此，设计了一种具有20米孔径反射器的高功率电磁脉冲辐射系统。该系统能够在预设的空间和时间条件下发射纳秒电磁脉冲信号，为评估SGLLN的探测能力提供可控环境。在设计阶段，首先基于高增益辐射原理设计了指数型TEM馈电天线。馈电天线采用集成脉冲发生器的设计以降低绝缘风险，并配备非对称保护负载，将反射能量降低85.7%。此外，基于洛夫等效原理提出了一种创新的增益损耗评估方法，以量化馈电天线对辐射场的影响。在实验阶段，在400米距离的远场实验中使用了专门的电场传感器。测量结果表明，在此距离处，信号的峰值场强为2.2 kV/m，上升时间为1.9 ns，脉冲半高宽为2.5 ns。此外，时域波束宽度小于10°。在500公里高度，星载探测器记录到一个峰值场强约为10 mV/m的信号。特别地，该信号在其频谱上转换为微秒范围内的非线性调频信号，这与电离层中无线电波传播规律一致。本研究为验证星载探测器提供了稳定可靠的辐射源，并为研究电离层对信号传播特性的影响奠定了经验基础。
