Remarkably slow propagation of microwaves in two different classes of left-handed materials ͑LHM's͒ is reported from microwave-pulse and continuous-wave transmission measurements. Microwave dispersion in a composite LHM made of split-ring resonators and wire strips reveals group velocity v g ϳ c / 50, where c is the free-space light velocity. Photonic crystals ͑PhC's͒ made of dielectric Al 2 O 3 rods reveal v g ϳ c / 10. Group delay dispersion of both the composite LHM and PhC's determined from the experiment is in complete agreement with that obtained from theory. The slow group velocities are quantitatively described by the strong dispersion observed in these materials.

Public reporting burden for this collection of information is estimateaverage 1 hour per response, including the time for reviewing instruct. ,earching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services. Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS.

Public reporting burden for this collection of information is estimat . average 1 hour per response, including the time for reviewing instructi, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS.

Public reporting burden for this collection of information is estimatt. .,average 1 hour per response, including the time for reviewing instructiu,•., searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. REPORT DATE (DD-MM-YYYY)2 The geometrical anisotropy and bi-anisotropy of a split ring and post type metamaterial is studied by free space microwave measurements in a frequency band near 13.5 GHz where it exhibits negative index of refraction. The orientation of the linearly polarized incident wave determines whether the refracted response is negative or positive. Measurements of cross polarization through the prism are 50% of the co-polarization. The insertion loss through the material of 3.36 dB/cm at 13.5 GHz, where the index n = -1, is therefore composed of both scattering and absorptive losses. SUBJECT