Design of Invisibility Cloak Assisted by 3-D Microwave Circuits

An invisibility cloak designed with 3-D microwave circuit assistance is proposed in this letter. Conformally wrapped around a square tube, the cloak achieves substantial radar cross-section (RCS) reduction while preserving the integrity of the incident electromagnetic wavefront. A microwave circuit model in 3-D space is proposed, and combined with the current distribution of full-wave simulation, the mechanism of the proposed structure is revealed. The cloak is fabricated on a conformal plastic substrate via an industrially compatible electroplating process, and the thickness is only $\lambda _{L}$/35 in the lowest operating frequency. Periodic-structure simulations, RCS simulations, and experimental RCS measurements exhibit good mutual agreement and closely match the 3-D circuit-model calculations. In the 3.1 GHz to 3.7 GHz frequency band, the cloak delivers over 10 dB of RCS reduction. It exhibits potential applications in both the field of stealth and the elimination of antenna wavefront blockage.