|Martijn Brethouwer, David Prinsloo
| Within the MFAA front-end project we wanted to know if several separate modules would work nicely together. We had already built Vivaldi antennas as well as the LNA modules which will be mounted on the antenna elements. We just finished the construction of two beamformer boards, which combine the signals from multiple LNA modules. To test these boards, we had constructed a controller which consists of a microcontroller and switches to route the data to the desired beamformer board. So, all in all we had the parts ready and functioning separately, and we would like to know if they would work in a system.
We decided that the easiest and quickest way to test the integration was to measure the noise temperature of an array. Therefore we attached 16 LNA modules to a large array of antenna elements, connected them to the beamformer boards, controlled those with the controller, crossed our fingers, and measured the output with a spectrum analyzer. The result of the measurement can be seen in the images above.
The system performed as expected with constant gain over the operating frequency bandwidth and no strange artifacts in the noise temperature measurement.
NB: The measurements have been performed with old LNA modules and many unconnected antenna elements. Both factors had a significant influence on the noise temperature of the array. Currently our new LNA modules are being characterized and a new noise temperature measurement is being planned. This measurement will show the true potential of dense connected arrays.