论文标题
低频偏光杆阵列干涉仪的系统等效通量密度
System equivalent flux density of a low-frequency polarimetric phased array interferometer
论文作者
论文摘要
本文扩展了Sutinjo，A。T。等人的系统等效通量密度（SEFD）的处理。 （2021）（纸I）到干涉阶段阵列望远镜。目的是开发一个仅涉及最基本假设的SEFD公式，并且很容易适用于阶段阵列干涉仪无线电观测值。然后，我们旨在比较所得的SEFD表达与经常使用的根平方（RMS）SEFD近似，Sefdrmsi =（1/2）（SEFD^2_xx + sefd^2_yy）^（1/2）^（1/2）研究SEFDRMS的不可能。 我们考虑了阵列环境中的所有相互耦合和噪声耦合（阵列内耦合）。这种阵列内噪声耦合通过阵列的实现噪声阻力包含在SEFD表达式中，这说明了系统噪声。对于天空的极化（或缺乏）或天线元件的正交性，没有任何假设。基本的噪声假设是，在相量表示中，给定噪声源的实际和虚构成分是独立的，平均值为零的（IID）。只要每个噪声源的真实和虚构成分是IID，互相相关且非IID的噪声源。系统噪声在阵列实体之间不相关，而阵列实体被基线距离隔开，而在默奇森广场阵列（MWA）的情况下，通常是数十个波长或更大的波长。通过将所得的SEFD公式与sefd_i^rms近似进行比较，我们证明了sefd_i^rms始终低估了SEFD，这导致了对数组敏感性的高估。
This paper extends the treatment of system equivalent flux density (SEFD) in Sutinjo, A. T. et al. (2021) (Paper I) to interferometric phased array telescopes. The objective is to develop an SEFD formula involving only the most fundamental assumptions and one that is readily applicable to phased array interferometer radio observations. Then, we aimed at comparing the resultant SEFD expression against the often-used root-mean-square (RMS) SEFD approximation, SEFDrmsI = (1/2)(SEFD^2_XX + SEFD^2_YY)^(1/2) to study the inaccuracy of the SEFDrms. We take into account all mutual coupling and noise coupling within an array environment (intra-array coupling). This intra-array noise coupling is included in the SEFD expression through the realized noise resistance of the array, which accounts for the system noise. No assumption is made regarding the polarization (or lack thereof) of the sky nor the orthogonality of the antenna elements. The fundamental noise assumption is that, in phasor representation, the real and imaginary components of a given noise source are independent and equally distributed (iid) with zero mean. Noise sources that are mutually correlated and non-iid among themselves are allowed, provided the real and imaginary components of each noise source are iid. The system noise is uncorrelated between array entities separated by a baseline distance, which in the case of the Murchison Widefield Array (MWA) is typically tens of wavelengths or greater. By comparing the resulting SEFD formula to the SEFD_I^rms approximation, we proved that SEFD_I^rms always underestimates the SEFD, which leads to an overestimation of array sensitivity.
