This study deals with the affine transformation that is used to convert the triangular element grid of a planar phased array antenna into a square one. By means of this kind of transformation, it is possible to apply the iterative Fourier transform (IFT) method to synthesise low sidelobe tapers for array antennas featuring a triangular grid. Combination of the IFT method with an affine transformation allows the synthesis of low sidelobe tapers of which the peak sidelobe level does not vary with changing frequency and/or altering main beam position. The considered affine transformation was already briefly addressed in earlier publications of this author. In this study detailed information is given on its use in combination with the IFT method. Examples to demonstrate the effectiveness of the combination affine transformation and the IFT method for triangular grid array antennas are given. It will be shown that the peak sidelobe levels of the obtained tapers are invariant with frequency and scan angle when all far-field directions of the array factor are involved in the low sidelobe taper synthesis.

中文翻译：

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使用IFT方法在具有三角形单元网格的平面阵列天线中合成低旁瓣图案的仿射变换

这项研究涉及仿射变换，该仿射变换用于将平面相控阵天线的三角形单元网格转换为正方形。通过这种变换，可以将迭代傅立叶变换（IFT）方法应用于合成具有三角形网格的阵列天线的低旁瓣锥度。IFT方法与仿射变换的结合可以合成低旁瓣锥度，其峰值旁瓣电平不会随频率和/或主波束位置的变化而变化。在作者的早期出版物中已经简要介绍了所考虑的仿射变换。在这项研究中，给出了结合IFT方法使用它的详细信息。举例说明了仿射变换和IFT方法在三角网格阵列天线中的有效性。将显示出，当阵列因子的所有远场方向都参与低旁瓣锥度合成时，所获得的锥度的峰值旁瓣电平随频率和扫描角而不变。