1.50 Calculated local fields (absolute value relative to that of the excitation field) in the equatorial plane of symmetry for the linear self-similar chain of three silver nanospheres, Ri is the radius of the ith sphere and d i ,i+1 is the distance between the surfaces of the ith and (i + 1)th spheres. Inset: the geometry of the system in the cross section through the equatorial plane of symmetry [27]. 2.1 Patterned ground microstrip bandstop resonator (a) dumbbell-shaped (Jan. 2001) [3], (b) spiral-shaped (Jun. 2002) [4], (c) double-H-shaped (Feb. 2006) [6], (d) modified dumbbell-shaped (Sept. 2006) [28], (e) T-shaped (Sept. 2007) [9], and (f) E-shaped. 71 2.2 The V-slot patterned ground microstrip bandstop resonator [7]. 2.3 Slotted ground microstrip bandstop resonators adopted V-slot geometries 2.4 S21-parameters of the patterned ground structures when they are designed to resonate at fo = 5 GHz.