Anisotropic Mantle Cloaks for TM and TE Scattering Reduction

Design of cloaked Yagi-Uda antennas

“…Please note that, though derived in a planar configuration, the accuracy of this formula for cylindrical geometry has been confirmed in several previous publications [10,11]. The required surface reactances to cloak the three finitelength cylinders composing the Yagi-Uda antenna at the central frequency of BW b can be computed following the procedure outlined in [13]. Once these values are known, by using (Eq.…”

“…The design procedure presented in this work can be applied to any frequency range of interest and considered as a nontrivial generalization of our previous results on the cloaking of finite-length metallic cylinders [11,13] and dipole antennas [14,19]. Compared to these earlier results, in fact, the presence of two or more parasitic elements acting as loads of the driven dipole introduces significant complications in the achievement of a final working design.…”

“…(1)) it is possible to quickly design three horizontal-strip metasurfaces. The geometrical parameters of the final cloaks, made of N r = 12 and N c = N d = 8 rows, respectively, are reported in Table 2, whereas in Figure 4 we show the dispersive behavior of the designed metasurfaces, retrieved using a simple full-wave procedure based on a transmission-line model [13]. Due to its sub-wavelength pattern, the designed cloaks can replace the ideal ones used during the Yagi-Uda optimization without affecting the antenna performance.…”

“…Differently from well-established radar cross section reduction (RCSR) techniques [10], in fact, cloaking allows reducing the overall scattering cross section (SCS) of an object, making it significantly less detectable to an external observer or to a sensor within the desired frequency range. Among the various cloaking techniques proposed so far, mantle cloaking [5,6] is particularly promising for antenna applications at microwave frequencies, due to its straightforward implementation [11] and the availability of accurate analytical models [12,13] resulting in quick and effective design procedures. Moreover, as it happens in any scattering cancellation based approach to cloaking, the concealed object is not electromagnetically isolated and, thus, the mantle cloaking can be successfully applied to different antenna scenarios, with remarkable advantages for both transmitting [14][15][16][17][18][19] and receiving [20] antennas.…”

“…As is now well known, a mantle cloak is made of a properly patterned metallic surface (i.e., a metasurface) supported by a dielectric layer and exhibiting a desired value of intrinsic surface reactance X s (X/sq) [12,13]. Since the cloaking of a metallic cylinder requires a capacitive metasurface [7], the generic cloaks shown in Figure 1b are made of thin horizontal metallic strips.…”