Near-field Focusing through Higher-order Cylindrical Leaky Waves
The possibility of generating a higher-order non-diffracting Bessel beam by means of a fast backward spatial harmonic is discussed in this work. The focusing features of the radiated near field are achieved by the excitation of a higher-xorder cylindrical leaky wave supported by an annular metal-strip grating placed on a grounded dielectric slab, which is excited by a circular arrangement of elementary sources.