Changing the polarization of microstrip antenna by metamaterial and transformation optics

In this letter, we show by the theoretical analysis and computer simulation that the polarization of microstrip antenna can be changed using metamaterial with homogeneous constitutive parameters by applying the transformation optics approach, which is used to design the invisible cloak. We demonstrate that, the distribution of electric field between patch and ground-plane will be altered by filling in some properly designed metamaterial instead of traditional substrate, then, according to the cavity mode theory, some features of antenna's radiation will be also changed, such as polarization. As examples, we design a layout of metamaterial by coordinate transformation, which can make the microstrip antenna realize dual-band or circular polarization.