An Ultrawideband Fully Planar Inverted-L Element (FILE) Array

A novel element for ultrawideband (UWB) tightly coupled arrays (TCAs) is introduced called the fully planar inverted-L element (FILE). Our FILE element is inspired by a traditional monopole antenna, thereby reducing its complexity in both design and fabrication. It offers a unique solution to realize UWB tightly coupled dipole arrays (TCDAs) in the V- and W- millimeter-wave (mmWave) bands. The unit cell of the FILE array consists of an inverted-L shaped radiator that is capacitively coupled to two grounded vias. This innovative design effectively shifts the common-mode resonance (CMR) and loop-mode resonance (LMR) outside the desired frequency range. Infinite array simulations of our array demonstrate an operational bandwidth of 3:1 (33–101 GHz) with VSWR<3 for a maximum scan angle of ±45° for all principal E-, H-, and D-planes. The measured results align closely with these simulations, validating the performance of our FILM array.