  The effects of electric and magnetic loss factors on zero-mu and zero-epsilon
gaps in a one-dimensional lossy photonic crystal composed of double-negative
and double-positive materials are theoretically investigated by employing the
characteristic matrix method. This study contradicts the previous reports as it
indicates that by applying the inevitable factors of electric and magnetic
losses to the double-negative material, the zero-mu and zero-epsilon gaps
appear simultaneously in the transmission spectrum, being independent of the
incidence angle and polarizations. Moreover, the results show that these gaps
appear not only for an oblique incidence but also in the case of normal
incidence, and their appearance at the normal incidence is directly related to
the magnetic and electric loss factors. Besides, the results indicate that as
the loss factors and angle of incidence increase, the width of both gaps also
increases.
