A new incoherent scatter radar called EISCAT 3D is being constructed in northern Scandinavia. It will have the capability to produce volumetric images of ionospheric plasma parameters using aperture synthesis radar imaging. This study uses the current design of EISCAT 3D to explore the theoretical radar imaging performance when imaging electron density in the E region and compares numerical techniques that could be used in practice. Of all imaging algorithms surveyed, the singular value decomposition with regularization gave the best results and was also found to be the most computationally efficient. The estimated imaging performance indicates that the radar will be capable of detecting features down to approximately 90×90 m at a height of 100 km, which corresponds to a $\approx \mathrm{0.05}{}^{\circ }$ angular resolution. The temporal resolution is dependent on the signal-to-noise ratio and range resolution. The signal-to-noise ratio calculations indicate that high-resolution imaging of auroral precipitation is feasible. For example, with a range resolution of 1500 m, a time resolution of 10 s, and an electron density of $\mathrm{2}\times {\mathrm{10}}^{\mathrm{11}}{\mathrm{m}}^{-\mathrm{3}}$, the correlation function estimates for radar scatter from the E region can be measured with an uncertainty of 5 %. At a time resolution of 10 s and an image resolution of 90×90 m, the relative estimation error standard deviation of the image intensity is 10 %. Dividing the transmitting array into multiple independent transmitters to obtain a multiple-input–multiple-output (MIMO) interferometer system is also studied, and this technique is found to increase imaging performance through improved visibility coverage. Although this reduces the signal-to-noise ratio, MIMO has successfully been applied to image strong radar echoes as meteors and polar mesospheric summer echoes. Use of the MIMO technique for incoherent scatter radars (ISRs) should be investigated further.

中文翻译：

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使用EISCAT 3D进行雷达成像

斯堪的纳维亚北部正在建造一种名为EISCAT 3D的新型非相干散射雷达。它具有使用孔径合成雷达成像技术产生电离层等离子体参数的体积图像的能力。这项研究使用EISCAT 3D的当前设计来探索在E区域成像电子密度时的理论雷达成像性能，并比较可以在实践中使用的数值技术。在所有调查的成像算法中，带正则化的奇异值分解给出了最佳结果，并且被发现是计算效率最高的。估计的成像性能表明，该雷达将能够在100 km的高度上检测低至约90×90  m的特征 ，这对应于$\approx \mathrm{0.05}{}^{\circ }$角分辨率。时间分辨率取决于信噪比和范围分辨率。信噪比计算表明对极光降水进行高分辨率成像是可行的。例如，距离分辨率为1500  m，时间分辨率为10 s，电子密度为$\mathrm{2}\times {\mathrm{10}}^{\mathrm{11}}{\mathrm{米}}^{--\mathrm{3}}$，可以测量E区雷达散射的相关函数估计值，不确定度为5％。在10 s的时间分辨率和90×90  m的图像分辨率下，图像强度的相对估计误差标准偏差为10％。还研究了将发射阵列划分为多个独立的发射器以获得多输入多输出（MIMO）干涉仪系统的方法，并且发现该技术通过改善可见度覆盖范围来提高成像性能。尽管这降低了信噪比，但MIMO已成功应用于像流星和极地中层夏季回波之类的强雷达回波成像。MIMO技术用于非相干散射雷达（ISR）的用途应进一步研究。