A synthesis constitution(SC)method of metamaterials which have an electric response and a magnetic response is proposed. The metallic triangular open loop resonators etched on the dielectric board have the magnetic response

i.e.

the negative permeability; and the metallic wire arrays etched on the dielectric board have the electric response

i.e.

the negative permittivity. Through locating the wire in the middle part of the loop and combining the two structures mentioned above

the SC method constitutes the triangular electromagnetic resonator(TER)which simultaneously has the magnetic and the electric responses and composes the novel metamaterials in the TER array form. Both theoretical simulation and experiment measurement prove that compared with the conventional split ring resonator(SRR)and wire structure

TER have the dual stopbands property which corresponds to the electric and magnetic responses. Moreover

the left-handed passband of the double negative metamaterial composed of TER-wire is 217% wider than that of the conventional SRR-wire design.