A Wideband Generalization of the Near-Field Region for Extremely Large Phased-Arrays
A Wideband Generalization of the Near-Field Region for Extremely Large Phased-Arrays
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DOI：
10.1109/lwc.2022.3233011
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发表时间：
2022-06
影响因子：
6.3
通讯作者：
N. Deshpande;Miguel R. Castellanos;Saeed R. Khosravirad;Jinfeng Du;H. Viswanathan;R. Heath
中科院分区：
文献类型：
--
作者：
N. Deshpande;Miguel R. Castellanos;Saeed R. Khosravirad;Jinfeng Du;H. Viswanathan;R. Heath
传统无线系统设计中的窄带和远场假设导致了与宽带和近场系统所需的最佳波束形成不匹配。对于较大的孔径和带宽，这种差异会加剧。为了描述近场和宽带系统的特性，我们推导了为平面波传播而设计的频率平坦相控阵所实现的波束形成增益表达式。为了确定宽带系统的远场和近场边界，我们提出了一种频率选择距离度量。所提出的远场阈值在远离中心频率的频率上增加。分析得出阵列孔径与系统带宽乘积的基本上界。我们给出了数值结果来说明增益阈值如何影响n260和n261 5G NR频段的最大可用带宽。
The narrowband and far-field assumption in conventional wireless system design leads to a mismatch with the optimal beamforming required for wideband and near-field systems. This discrepancy is exacerbated for larger apertures and bandwidths. To characterize the behavior of near-field and wideband systems, we derive the beamforming gain expression achieved by a frequency-flat phased array designed for plane-wave propagation. To determine the far-field to near-field boundary for a wideband system, we propose a frequency-selective distance metric. The proposed far-field threshold increases for frequencies away from the center frequency. The analysis results in a fundamental upper bound on the product of the array aperture and the system bandwidth. We present numerical results to illustrate how the gain threshold affects the maximum usable bandwidth for the n260 and n261 5G NR bands.