SGER: A New Method for Landmine Detection and Minefield Mapping

0225424布朗这项提案是根据探索性研究小额拨款(SGER)计划提交的，它侧重于回答与探测和定位埋在地下的地雷和未爆弹药的新技术有关的关键可行性问题。该技术包括一个对峙的地面脉冲雷达，它将电磁能量发射到诺顿表面波传播模式中。诺顿表面波在真空中以光速沿空-地表面传播，并由于地面的损失而衰减到地面。通过适当地选择频率，地雷将沿着相同的传播路径散射回足够的能量，然后被雷达接收。这种能量通常不足以超过系统噪声水平，因此使用相干技术进行返回脉冲平均。如果对N个返回脉冲进行相干平均，则信噪比将增加N倍，从而使来自地雷的散射信号可被探测到。利用脉冲宽度在距离坐标上进行分辨，利用雷达天线在方位角上进行分辨来实现对水雷的定位。为了在天线附近实现区域覆盖和最佳的角度分辨率，建议同时使用波束控制和近场聚焦技术。为了确定可行性，关键的研究是确定诺顿表面波在表面传播并穿透足够深以探测杀伤人员和反坦克地雷的最高工作频率。还建议建立适当的Norton表面波雷达距离方程，研究最大化雷达天线与Norton表面波耦合的技术，确定典型有色金属地雷的土壤电导率和雷达截面值的变化，并研究最大距离和角度分辨率或可接受的工作频率。在回答了这些问题之后，应该可以确定这种雷达的可行性，只需计算表面粗糙度和埋在地下的碎片对地雷散射信号强度的影响，即低信杂比问题。

0225424BrownThis proposal is being submitted under the Small Grants for Exploratory Research (SGER)program and it focuses on answering critical feasibility questions pertaining to a newtechnique for the detection and location of buried landmines and unexploded ordnance. Thesubject technique comprises a standoff, ground based, pulsed radar that launcheselectromagnetic energy into the Norton surface wave mode of propagation. The Nortonsurface wave travels along the air-ground surface at the speed of light in a vacuum andexponentially decays into the ground due to the losses in the ground. By selecting thefrequency properly, sufficient energy will be scattered by the landmine back along thesame propagation path and then received by the radar. This energy is usually insufficientto be above the system noise level so return pulse averaging is carried out using coherenttechniques. If N return pulses are averaged coherently the signal-to-noise power ratiowill increase by a factor of N rendering the signal scattered from the landminedetectable. Location of the mine is achieved by using the pulse width to accomplishresolution in the range coordinate and the radar antenna to achieve resolution in theazimuth angle. In order to achieve area coverage and the best possible angular resolutionclose to the antenna, it is proposed to simultaneously employ both beam steering and nearfield focusing techniques. The critical study, to establish feasibility, is thedetermination of the highest operating frequency for which the Norton surface wave canpropagate on the surface and penetrate sufficiently deep to detect antipersonnel andantitank mines. It is also proposed to develop the appropriate radar range equation forthe Norton surface wave, investigate techniques for maximizing the coupling of the radarantenna to the Norton surface wave, determine the variation of soil conductivity and theradar cross section values for typical nonferrous landmines, and investigate the maximumrange and angle resolution or the acceptable frequencies of operation. Having answeredthese questions, it should be possible to establish the viability of such a radar subjectonly to the need to compute the effects of surface roughness and buried debris on the minescattered signal strength, i.e., the low signal-to-clutter ratio problem.