A novel small‐period wiggler constructed of edgy‐wound bifilar‐helical conducting sheets with ferromagnetic cores, intended for free‐electron lasers (FELs), is presented, and the performance characteristics of the wiggler prototype with 10‐mm period are measured. A field as high as 500–1000 G has been obtained. It is feasible to make a Raman FELs with this type of wiggler operating in the wavelength range of millimeters and submillimeters with a low electron energy (<500 keV) beam.