The Low Noise Tile: First array results

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In our series of daily images (18-12-2013 and 21-02-2014) on the progress of the Low Noise Tile (LNT) project, today's image shows the results for a small 2x2-element array with the new LNT antenna elements. The noise performance of this array has been measured in a 1 m^2 tile, largely filled with antenna/frontend LNA elements of the 'old LNT' design , except for the four center elements, which are from the new design. The results are shown in the accompanying figure and are compared with a similar 2x2 array of the previous design, showing the expected array noise temperature improvement of 10-15 K.

The other graph shows the results for the same 2x2 arrays, but now measured in the Compact Tile, a small test setup with 23 antenna elements. The picture shows the 1 m^2 tile with the Compact Tile in front. Besides the 4 center elements the Compact Tile is filled with elements of the previous design. Again the improvement of 10-15 K may be observed for the new LNT design.

The results as a function of frequency for the Compact Tile are better than for the larger 1 m^2 tile. This is caused by a lower contribution to the array noise temperature from noise coupling between the elements, in line with the better noise properties of the new design and the lower number of neighbor LNT elements. This is even more clearly visible in the Compact Tile results without surrounding elements, where these elements cannot contribute to the noise coupling. These results promise consistent array noise temperatures well below 40 K for the compact and larger arrays, when these arrays will be completely filled with the new LNT-modules.

These results promise consistent array noise temperatures well below 40 K for the compact and larger arrays, when these arrays will be completely filled with the new LNT-modules. Production of a large number of these modules is now ongoing. Results will be presented in a future daily image.