Synthetic Aperture Imaging with ⊤-, + -, or × -Shaped Arrays: Cartesian or Hexagonal Sampling?
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| Title: | Synthetic Aperture Imaging with ⊤-, + -, or × -Shaped Arrays: Cartesian or Hexagonal Sampling? |
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| Authors: | Anterrieu, Eric1 (AUTHOR) eric.anterrieu@cnrs.fr, Esmati, Zahra2 (AUTHOR), Rodríguez-Fernández, Nemesio1 (AUTHOR), Walker, Jeffrey2 (AUTHOR) |
| Source: | Remote Sensing. May2026, Vol. 18 Issue 9, p1280. 35p. |
| Subjects: | Antenna arrays, Sampling (Process), Spatial resolution, Microwave radiometers, Microwave radiometry, Synthetic apertures |
| Abstract: | Highlights: What are the main findings? Key parameters of an antenna array devoted to imaging radiometry must be established in a specific order: first the parameters setting the shape and the extent of the alias-free field-of-view, then those driving the spatial resolution, and finally those governing the radiometric sensitivity. This study shows how it is possible to perform aperture synthesis on hexagonal sampling grids with antenna arrays whose geometry naturally leads to Cartesian sampling grids, with fewer, but wider, elementary antennas and without degrading imaging performance. What are the implications of the main findings? For these arrays operating aperture synthesis on Cartesian sampling grids but suffering from very, even too close elementary antennas, the short spacing can be increased by slightly changing the location of the antennas in order to perform aperture synthesis on hexagonal grids, without modifying the shape, the dimensions, or the performance of the imaging radiometer. The FRESCH project was initially designed for performing aperture synthesis over Cartesian grids with a four-arm array fed with 171 small antennas and a short spacing set to 0.71 λ . Thanks to this study, it is possible to enlarge this short spacing up to 0.82 λ and to carry out aperture synthesis over hexagonal grids with 167 wider antennas distributed over the same four arms and with the same imaging performance. The key performance of microwave imaging radiometers by aperture synthesis is governed by spatial resolution, radiometric sensitivity, and the extent of the synthesized field of view that is free from any aliasing artifact. Accordingly, this work is concerned with the choice of key parameters of an antenna array, such as its geometrical shape and the number of elementary antennas as well as their spacing, in order to meet the required scientific specifications and satisfy the necessary engineering constraints. This study is illustrated with two examples: the + -shaped array selected for the Fine Resolution Explorer for Salinity, Carbon, and Hydrology (FRESCH) and a ⊤-shaped array proposed for use onboard a High-Altitude Pseudo-Satellite (HAPS), being two high-resolution microwave imaging radiometers by aperture synthesis. Both cases show how it is possible to perform aperture synthesis on hexagonal sampling grids with antenna arrays whose geometry naturally leads to Cartesian sampling grids, with fewer elementary antennas and without degrading imaging performance while also solving computational issues. [ABSTRACT FROM AUTHOR] |
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| Database: | Engineering Source |
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