Daily Image
24-07-2007
Evolution of a LOFAR HBA antenna
| Submitter: | Henri Meulman |
| Description: | From left to right you see the first prototype to the latest version of the HBA antenna. Not only the mechanical design did improve every step in the design process, but also the electronic design became more complex (and better). In the first prototype the electronics in the center of the antenna had only two Low Noise Amplifiers (LNA). To improve the protection against environmental conditions s.a. rain and wind, Astron did design a mechanic construction (second antenna). 4x16 antennas has been made and placed in Westerbork for validation of the concept (compared with the WSRT telescopes). The signals of each 4x4 array are combined and delayed (if necessary) in a separate beamformer. In the third concept the functionality of the beamformer is transferred into the Front-end LNA. The housing became bigger. The digital communication for steering the beam and the supply of the power were now distributed via the same cable as the RF signal from the antenna’s. This is all done to make the system more suitable for masse production. In this design the noise level of the LNA was improved (lower noise) and the delay steps were more accurate. In the forth concept Autonational did design the housing. Mechanical strength and environmental shielding did improve. The Front-end LNA where redesigned to consume only half of the power. What is missing in the picture is a plastic bag on top of the white construction to protect against the rain. 6 arrays of 16 antennas are placed in the core of LOFAR near Exloo together with 30 single antennas of the third concept. |
| Copyright: | Astron, Autonational |
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