Guest Editorial for the Special Issue on Innovative Phased Array Antennas Based on Non-Regular Lattices and Overlapped Subarrays

There has been a renewed interest in phased arrays based on non regular lattices or overlapped subarrays for different types of applications ranging from spaceborne to ground antennas, from civil to military systems. The objective of this special issue consists in providing an overview of the current state-of-the-art in this field, highlighting the latest developments and innovations, and proposing new applications, solutions and challenges for the future. The main topics considered are: 1. sparse and thinned arrays; 2. overlapped and interlaced subarrays; 3. beamforming and multibeam excitation of irregular arrays; 4. fabrication and signal distribution networks for large arrays; 5. overlapped and non-regular conformal arrays; 6. synthesis using irregular and overlapped subarrays. Most of the papers selected are in the area of array antennas based on nonregular lattices. Papers were selected based on detailed peer review and relevance to the topic. Papers are grouped into two main categories: a) array antennas based on non-regular lattices and b) array antennas organized in overlapped subarrays. The papers are briefly summarized.