Mitigating Quantization Lobes in mmWave Low-Bit Reconfigurable Reflective Surfaces
Mitigating Quantization Lobes in mmWave Low-Bit Reconfigurable Reflective Surfaces
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DOI：
10.1109/ojap.2020.3034049
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发表时间：
2020-01-01
影响因子：
4
通讯作者：
Trichopoulos, Georgios C.
中科院分区：
文献类型：
--
作者：
Kashyap, Bharath G.;Theofanopoulos, Panagiotis C.;Trichopoulos, Georgios C.
我们提出了一种方法，用于减轻量化波瓣在单比特可重构反射表面（RRS）。通常，RRS是由具有集成可调谐开关的数百或数千个天线组成的平面波束成形结构。在平面波照射下，单位RRS遭受不期望的旁瓣或量化波瓣，这是由由于相位量化中使用的有限数量的比特而引起的误差的周期性引起的。在本文中，我们提出了一种拓扑结构，通过在每个单元中实现固定但随机的相位延迟，使用单层1位RRS来抑制量化波瓣。相位随机化的引入打破了量化误差的周期性，从而降低了量化波瓣电平（QLL）。我们进行了理论分析，以证明相位随机化的效果在RRS，并首次提供了选择所需的随机化范围，以实现最低的旁瓣电平（SLL）的条件。利用这个条件，我们设计了一个单层，1位30 x 30随机RRS在222.5 GHz。反射表面是在康宁公司的薄的、低损耗的氧化铝带陶瓷晶片上制造的。使用适合于大规模生产毫米波/太赫兹RRS的简化制造技术。最后，我们提出的雷达截面（RCS）的表征结果从一个准光学测量设置验证缓解量化波瓣使用建议的随机化技术。
We present a method for the mitigation of quantization lobes in single-bit reconfigurable reflective surfaces (RRSs). Typically, RRSs are planar beamforming structures consisting of hundreds or thousands of antennas with integrated tunable switches. Under plane-wave illumination, single-bit RRSs suffer from undesired side lobes or quantization lobes, which are caused by the periodicity of the errors due to the limited number of bits used in phase quantization. In this article, we present a topology that suppresses the quantization lobes using single-layer, 1-bit RRSs, by implementing a fixed but random phase delay in every unit-cell. The introduction of phase randomization breaks the periodicity of the quantization errors, thus reducing the quantization lobe level (QLL). We carry out a theoretical analysis to demonstrate the effect of phase randomization in RRSs, and for the first time, provide the condition for choosing the range of randomization required to achieve the lowest sidelobe level (SLL). Leveraging this condition, we design a single-layer, 1-bit 30 x 30 randomized RRS at 222.5 GHz. The reflective surface is fabricated on a thin, low-loss alumina ribbon ceramic wafer from Corning Inc. using a simplified fabrication technique suitable for large-scale production of mmWave/THz RRSs. Finally, we present the radar cross-section (RCS) characterization results obtained from a quasi-optical measurement setup validating the mitigation of quantization lobes using the proposed randomization technique.