Mid-Frequency Aperture Array

MidFrequencyApertureArray_blue

The AAMID Consortium, working on the Mid-Frequency Aperture Array (MFAA), an Advanced Instrumentation Work Package, aims to demonstrate the feasibility, competitiveness and cost-effectiveness of MFAA technology for SKA2. The key advantage of AAs is the capability of realising a very large Field of View and sensitivity, which results in an unsurpassed survey speed. Furthermore, AAs are capable of generating multiple independent FoVs, enhancing the efficiency of the system, for calibration and for multiple concurrent observations.

Aperture Array Front-End design for Mid-Frequency Aperture Array

The beamformer network for the MFAA prototype is investigated further. A comprehensive GUI to control the phase and amplitude at the element level (8×8 dual polarised finite array) is given in the Fig. 1. The control of the beamformer has a modular design. Therefore, the whole system is scalable and number of sub-tiles or elements can be added easily in the beamformer control system. The modular design is shown in Fig. 2.

Figure 1. The GUI for the channel response measurements.

Figure 2. The beamformer control – a modular design.

The channel responses from different channels with various delay steps applied have been characterised. For the quad board, for the same chip with different channels, such as channel 1&3, the measured absolute time delay is shown in Fig. 3. The correlation between channels appears to be no difference.

Figure 3. The channel delay responses at different channels on the same chip on the quad board.

However, some delay differences are observed for the channels from different chip, such as for the chip 54 and 55, when the channel 3 are measured for both chips, the delay performance is shown in Fig. 4. A significant discrepancy from the same delay step can be observed. This will needs to be calibrated out before further beamforming steps.

Figure 4. The channel delay responses from different chips on the quad board.

The relative time delay over different frequency is shown in Fig. 5. Approximately 2.4ns total delays can be achieved, however, there are small differences from different channels.

Figure 5. The relative time delays in different channels at the maximum delay step.

Outreach Activities of MFAA

MFAA front-end team joined the “Towards an All-Sky Radio SETI Telescope” workshop at JBCA.

http://www.jodrellbank.manchester.ac.uk/news-and-events/wide-field-seti-workshop/

Two presentations have been given:

  • All‐Sky Multimode Antennas – David Prinsloo
  • RAAIR and SETI – David Zhang

Report provided by the AAMID Consortium