Multi-Port Element for Grating Lobe Suppression in Sparse VHF Phased Array Radars

A multi-port element approach, engineered to address practical design challenges of very high-frequency (VHF) phased array radar systems, is presented in this communication. A cornerstone of the antenna element design is its simplicity, which counteracts the mobility issues of physically large and unavoidably bulky ground-based VHF radar systems. The multi-port element introduces a third dimension in the otherwise planar array configuration. Using a nonlinear optimization scheme to realize a set of matching networks for the element, the active loading from surrounding elements in the array environment is suppressed resulting in a nondistorted embedded element pattern. The element is compared to the resembling Yagi-Uda design in terms of standard multi-port and radar metrics. The simulated results indicate that the element enables a significant suppression of grating lobes when beam steering within a limited angular sector, which in turn has an overall positive impact on the array performance.