Anisotropic Modification of Maxwell's Equations

This paper examines a modified form of Maxwell's equations, one designed to produce anisotropic light propagation in a vacuum. The equations predict anisotropies in the speed of light that behave as $cos\phi$ and $cos2\phi$, where $\phi$ is the angle between the actual direction of propagation and some single preferred direction in space. The predicted index of refraction also has terms that behave as $cos\phi$ and $cos2\phi$.