Ferromagnetic microwires are investigated as fundamental components to generate metamaterials with double negative parameters. Electric and magnetic responses are, respectively, based on the finite conductivity and ferromagnetic resonance of the wires that in turn depend on their chemical composition. Tuning properties of samples are investigated in terms of the composition of the alloy and the applied magnetic field. The samples are measured and simulated in a waveguide environment for a large microwave frequency range. Numerical modeling supports the experimental results and helps to understand the physics involved in the transmission phenomena. Radius and conductivity of the wires are pointed out as the most critical parameters to generate a double negative response in terms of permittivity and permeability.