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Localized waves, ie, the wide class of limited-diffraction, limited-dispersion solutions to the wave equation are generally characterized by real wave numbers. We consider the role played by localized waves with generally complex “leaky” wave numbers. First, the impact of the imaginary part of the wave number (ie, the leakage constant) on the diffractive (spatial broadening) features of monochromatic localized solutions (ie, beams) is rigorously evaluated. Then general conditions are derived to show that only a restricted class of spectra (either real or complex) allows for generating a causal localized wave. It turns out that backward leaky waves fall into this category. On this ground, several criteria for the systematic design of wideband radiators, namely, periodic radial waveguides based on backward leaky waves, are established in the framework of leaky-wave theory. An effective design method is proposed to …
American Physical Society
Publication date: 
3 May 2018

Walter Fuscaldo, Davide Comite, Alessandro Boesso, Paolo Baccarelli, Paolo Burghignoli, Alessandro Galli

Biblio References: 
Volume: 9 Issue: 5 Pages: 054005
Physical Review Applied