  In this paper, we utilize the deformation transformation optics (DTO) method
to design electromagnetic beam bender, which can change the direction of
electromagnetic wave propagation as desire. According to DTO, the transformed
material parameters can be expressed by deformation tensor of the spatial
transformation. For a beam bender, since the three principal stretches at each
point induced by the spatial transformation are independent to each other,
there are many possibilities to simplify the transformed material parameters of
the bender by adjusting the stretches independently. With the DTO method, we
show that the reported reduced parameters of the bender obtained by equivalent
dispersion relation can be derived as a special case. An isotropic bender is
also proposed according to this method, and it is fabricated by stacking
dielectric materials in layered form. Experiments validate the function of the
designed isotropic bender for a TE wave; it is also shown that the isotropic
bender has a broadband with low loss, compared with the metamaterial bender.
The isotropic bender has much easier design and fabrication procedures than the
metamaterial bender.
