Near-Field to Far-Field Pattern Measurements for a Mid-Aperture FR-ORA Array

In this communication Near-Field to Far-Field (NF/FF) measurements are employed to characterize the radiation pattern of a prototype of 9 x 9 finite array antenna element proposed for radio astronomy. The antenna design is a tightly coupled phased array designed to function in the 0.3 - 1.3 GHz band. The developed antenna is a composite structure to achieve ultra-wideband performance. It is likely to be competitive over related technologies because of its exceptional bandwidth, its light weight construction, its low cost (because of the planar design and significantly lower metal content in the fractal elements), its low profile (planar structure), with dual polarisation and the potential steerability of the individual elements. Another unique feature of the open octagonal ring array is that the center frequency and bandwidth can be tailored to any specific application by scaling the element sizes in the active layer. Through the validation of three-dimensional electromagnetic simulations, the NF/FF transformation has proven to be a convenient and cost-effective method to determine far-field patterns of the array elements.