Low-profile ultra-wideband reconfigurable tightly-coupled arrays

Ultra-wideband (UWB) arrays are desirable for multi-functional apertures utilizing multiple beams, polarizations, and frequency bands to enable diverse communication and remote-sensing capabilities. The desired bandwidth, compactness, and scanning capability are often mutually conflicting. Here we present our current and previous work on developing arrays with 7:1 (loss less) and 14:1 (with R card) bandwidths. While the latter have been fabricated for operation up to 4 GHz, for many applications it is desirable to achieve extremely broadband performance at much higher frequencies. As an example, we present an array utilizing a simplified feed network in a single 4-layer PCB operating across a 6:1 band (3-18 GHz). Also we present a simple design capable of operating 28-68 GHz. More important, we have developed reconfigurable arrays capable of UWB operation and scanning. Design, simulation, fabrication, and measurement results for reconfigurable antenna arrays capable of band rejection are presented.