Dual-Band Cloak Using Microstrip Patch With Embedded U-Shaped Slot

In this work, a dual-band invisibility cloak based on series of interconnected U-slot patch antennas is proposed. The proposed cloak has a thickness of λ
_L
/73 (λ
_H
/36) at lower (higher) cloaking frequency f
_L
= 2.06 GHz (f
_H
= 4.11 GHz). AU-shaped slot designed on the patch antenna is responsible for dual-band operation, which leads to reduction in vertical length of the cloak unit cell, and a higher f
_H
/f
_L
(= 2) ratio is obtained compared to the previously reported dual-band cloak. The total scattering cross section of the proposed cloak is 0.11 and 0.25 with respect to the perfect electric conductor cylinder at 2.06 and 4.11 GHz, respectively. The parametric studies show that the ratio between operating frequencies and scattering cross section at the operating frequencies are dependent on geometrical parameters. In far field, the proposed dual-band cloak shows 12 and 10 dB reduction in the forward scattering compared to the perfect electric conductor at 2.06 and 4.11 GHz, respectively. Numerical simulation results of bistatic scattering patterns and electric field distributions confirm that the invisibility is observed at both the operating frequencies.