Microwave photonic crystal with tailor-made negative refractive index
  Negative refraction and left-handed electromagnetism in a metallic photonic crystal (PC) wedge are demonstrated in free space for both transverse magnetic and electric mode propagation. The experimental results are in excellent agreement with numerical calculations based on the band structure with no fit parameters used in modeling. The results demonstrate precision control on the design and fabrication of the PC to achieve tailor-made refractive indices between -0.6 and +1. 
P. Vodo, P. V. Parimi, W. T. Lu, R.Wing and S. Sridhar