Programmable Microwire Metacomposites

Traditionally,microwave tunability of microwire composites mainly relies on their topological factors,magnetic field/stress stimuli,and hybridization which are burdensome approaches and restricted to rather narrow band frequencies.In the present thesis,a range of microwire composite materials have been exploited to develop novel methods for controlling and programming the electromagnetic?EM?properties with merely a single-wire composition.Structural modification of one type of microwire(i.e.,Co₆₀Fe₁₅Si₁₀B₁₅ glass-coated microwires with a metallic core diameter of 27.2?m obtained by a modified Taylor-Ulitovsikiy technique)through suitable current annealing modulated Curie temperature,structural,magnetic and electrical properties.Moreover,the arrangement of the annealed wires with as-cast wires in multiple combinations was sufficient to distinctly red-shift the transmission dip frequency of the composites.In addition,increasing the wire concentration blueshifted the transmission band of the wire composites due to larger conductivity,whereas decreasing the wire periodicity redshifted the band owing to stronger inter-wire coupling.A larger blueshift was obtained by alternating as-cast and annealed wires due to an overlapped flow closure of fields from the same type of wires in an array.To further exploit the full use of composite intrinsic structure,we have proposed the concept of composites plainification by an in-built vertical interface on randomly dispersed short-cut microwire composites allowing the adjustment of EM properties to a large extent.Such interface was modified through arranging wires of different structures in two separated regions and by altering these regions through wire concentration variations leading to polarization differences across the interface and hence microwave tunability.Wire concentration fluctuations resulted in strong scattering changes ranging from broad passbands to stopbands with pronounced transmission dips.Further,Co-based microwires were incorporated into rubber matrix along with several other types of fibers in certain patterns,including graphene fibers and carbon fibers.Most traditional fillers used in electromagnetic shielding composites require high loading,uniform distribution and complicated structures for modest property enhancement.Combining the microwire with other functional fibers resulted in superior shielding effectiveness?SE?with respect to incorporating the same type of filler due to improved absorption,impedance matching and polarization triggered by the filler arrangement.The normalized SE of this composite was about two to four orders of magnitude higher than that of many existing shielding candidate materials.The proposed single-composition wire control-strategy endorses a programmable multivariable system that demonstrates a range of acquiescent electromagnetic functionalities and provides essential guidelines for the design and manufacture of high-performance microwave devices.The exploitation of the microwire composites via single wire-kind,high efficiency,low filler content,and economic processing will make them attractive for a plethora of engineering applications such as electromagnetic shielding,microwave absorption,and sensing.