Regular and irregular-on-grid sparse array comparison of connected aperture arrays

For square kilometer array (SKA) mid-frequency aperture arrays, dense connected aperture arrays such as Vivaldi antenna arrays are being considered, but to achieve the required system sensitivity for radio astronomical observations, this would mean a large number of antenna elements particularly in the order of millions. Two concepts of regular-on-grid and irregular-on-grid sparse array configuration are introduced for these connected arrays to reduce the number of antenna elements and the sensitivity performance of the two concept arrays is compared. Comparing the effective area of these two configurations, it is shown that a regular-on-grid sparse configuration achieves slightly larger effective area than an equivalent irregular-on-grid sparse configuration. Using the regular-on-grid sparse configuration as a case study, the effect that terminating impedance of the inactive antennas has on the receiver noise temperature of a connected array of Vivaldi antennas is investigated.