Low Noise Tile

© copyright ASTRON

The Low Noise Tile (LNT) project aims to demonstrate state-of-the-art noise performance of aperture arrays for the mid-frequency range (MFAA) of the SKA. A recent AJDI of December 18, 2013 showed the first measurements of the noise temperature of the new LNT frontend design based on the integrated SkyWorks LNA. This gives a considerable improvement over the previous one, which used using a discrete Avago transistor, and was shown in the AJDI of August 6, 2010. The AJDI of last December showed results of connectorized frontend boards/LNAs, with the promise of improved noise performance for an aperture array system.

Today, as a next step, we present a similar improvement for the new LNA, now integrated with the Vivaldi antenna element. The noise temperature was measured in a special single-antenna test fixture in THACO (for THACO see the AJDI of July 11, 2011). While the previous design gave a noise temperature of approximately 60 K in the test fixture, this has decreased to approximately 40 K for the new antenna element. The improvement gives a good indication of what may be achieved for an array of these new elements.

The images show the single antenna test fixture used for the measurements, the integrated antenna/frontend board, and a plot of the noise temperatures as a function of frequency for the "old" and the new LNT elements in the antenna test fixture.

We are now in the process of producing more new elements to place in the array, so we can directly compare the array performance using the "old" elements with that of the array with the improved LNT elements. Stay tuned for results of a 2x2 array soon, and results for a completely filled (~ 72 elements) array later.