Daily Image
04-10-2007
Measured DIGESTIF FPA Element patterns
| Submitter: | Wim van Cappellen |
| Description: | The DIGESTIF focal plane array is currently being evaluated extensively. One of the tests involved the measurement of the far field radiation patterns of the individual array elements on the sky (i.e. the element patterns after reflection on the dish). The patterns were measured on the geostationary Afristar satellite at 1490 MHz. The images above show the patterns of four array elements. Their positions in the array are also illustrated. It can be observed that the central elements, which are closest to the geometrical focus of the dish, have beams close to the telescope axis. The beams of the outer elements are scanned, providing the increased Field of View. But they also suffer from distortions, like an increased beam width and high sidelobes due to coma. The advantage of focal plane arrays is that, in theory, these distortions can be corrected by combining multiple elements of the array. One of the aims of the DIGESTIF project is to show that this also works in reality. |
| Copyright: | ASTRON, 2007. |
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