Apparatus and method for producing a flexible antenna suitable to be incorporated in a badge or similar object. The antenna comprises electrical windings (28, 38) surrounding a flexible antenna core (26, 36). The antenna core (26, 36) is of a material having a high quality factor formed of a plurality of mutually insulated, longitudinally extending chains of magnetic soft material of high .mu.. According to one embodiment, a powder of small particles of a magnetic soft material of high .mu. is mixed with a synthetic resin so that a high saturation of magnetic material in the mixture is formed in a vacuum. The mixture is cured in a strong magnetic field so that the particles form chains (18A, 18B, 18C) of the particle parallel to the applied magnetic field.