Prototype Design of a Modular Ultrawideband Wavelength-Scaled Array of Flared Notches

A prototype modular ultrawideband wavelength- scaled array of flared notches has been designed, built, measured and validated with full-wave modeling tools. Wavelength-scaled arrays operate over ultrawide bandwidths with significantly-reduced element counts, maintaining a relatively-constant beam size by utilizing phased-array radiators of different size. The prototype phased array presented here is designed to operate over an 8:1 bandwidth (1-8 GHz), demonstrating a 12-degree beam capacity at 2 GHz, 4 GHz, and 8 GHz. The architecture achieves a reduction in element count by a factor of 6.4-only 160 elements per polarization as compared to a conventional 1024-element phased array of the same aperture size-at the cost of reduced beamwidth capacity in the higher frequency range. Performance metrics (active VSWR and radiation characteristics) of the wavelength-scaled array are measured and validated against full-wave simulations. The technology is presented as a viable alternative to more expensive conventional ultrawideband arrays with dense uniform element layouts.

Phased arrays are an important component of future Navy multi-functional systems [1]. Like reflector antennas, phased arrays achieve high gain through large apertures. However, phased arrays can be expensive compared to reflector-based apertures when active components are required behind each element of the array. When scan-agile systems operate over a range of frequencies, or when large instantaneous bandwidths are required, ultrawideband (UWB) phased arrays are necessary. Typically, UWB electronics are not compact, adding an additional level of complexity to the already expensive problem of feeding the phased array.