Reciprocal Invisibility Cloak with Having Different Semi-axis

We propose a different semi-axis structure to study a reciprocal invisibility cloak that combines the coordinate transformation theory and complementary media. This cloak is different from the external cloak that needs “anti-object”, and conformal elliptical cloak that has identical shape between inner and outer boundary. The hidden object inside the cloak realizes the possibility of communicate with the outside world while maintaining a good invisibility performance without “anti-object”. In particular, this design has different semi-axis (the outer and inner boundary has different shape) so that it is more flexible for different shape object. At last, we take full wave simulation to demonstrate the validity of this design.