This invention relates to magnetic cores, and more particularly to simple magnetic cores formed of magnetically permeable strip material.
Saturable measuring devices, such as fluxgate magnetometers or gradiometers, require saturable cores. My prior U.S. Pat. No. 2,916,696, issued Dec. 8, 1959, discloses saturable measuring devices having magnetic cores formed by helically winding magnetically permeable wire, for example. In my prior U.S. Pat. No. 2,981,885, issued Apr. 25, 1961, I disclosed an improved type of magnetic core employing superposed oppositely wound coaxial coils of magnetically permeable strip material interwoven on a non-magnetic support. While this type of magnetic core is highly advantageous in many respects, such as the avoidance of permanent magnetization, manufacture of this type of core requires a high degree of skill in order to interweave the strips uniformly. In my prior U.S. Pat. No. 3,168,696, issued Feb. 2, 1965, I disclosed a further improvement in which a hollow cylinder of magnetically permeable material has a special configuration intended to provide the advantages of the interwoven strip type core, but without requiring the same degree of manufacturing skill. Nevertheless, the need has remained for an even simpler type of magnetic core having most, if not all, of the advantages of the interwoven core. The present invention is directed to the achievement of that goal.