A direct laser-synthesized magnetic metamaterial for low-frequency wideband passive microwave absorption

Microwave absorbion for radar stealth technology is facing challenges for effectiveness in the low frequency region. Here we report a new laser-based method to produce an ultra-wideband metamaterial based microwave absorber with a high sheet resistance uniformity and negative magnetic permeability leading to the highest relative bandwidth and lowest thickness in the L to S band reported so far. Control of electrical sheet resistance uniformity has been achieved to less than 5% deviation for 400 Ω/sq and 6% deviation for 120 Ω/sq, leading to a microwave absorption coefficient between 97.2%-97.7% within 1.56 GHz-18.3GHz bandwidth for incident angles of 0-40, and there is no need for applying energy or an electrical power source during operation. Porous N- and S- doped turbostratic graphene 2D patterns with imbedded magnetic nanoparticles are produced on polyethylene terephthalate simultaneously during laser direct writing. The proposed low frequency, wide band, wide incident angle and high electromagnetic absorption microwave absorber would have the potential for aviation, EMI suppression and 5G applications.