order to provide electrical insulation between the printed wiring 54 and 56 and the magnetic core 58 an adhesive layer 60 is utilized at the sites of the eventual connections to be produced openings are formed in the adhesive layer 60 and in the openings the exposed printed wiring material is tinned in order to produce the connection heat and pressure are applied through the polyamide film to the connecting zone so that a soldered joint 62 is produced between the sections 54 and 56 of the printed wiring by having recourse to the system described above for the production of a single layer winding it is possible while maintaining desired flexibility to arrive at a multi layer winding on the magnetic core as shown in fig9 a film 64 bears a printed wiring section 66 in order to constitute a first winding layer and printed wiring section 68 to form a second one in order to produce a twin layer hf antenna the magnetic core 70 is so positioned on the section 72 of the film 64 as is illustrated in broken lines in fig9 the film section 74 is then folded along the line 76 through 180 u00b0 onto the magnetic core 70.