FIELD: data transmission devices. SUBSTANCE: novelty is proposal to introduce deliberate error in impedance of data transmission and reception device antenna to reduce power consumption of alternating magnetic field of device required for operation of at least one portable data medium. To this end reactance is introduced in antenna for beyond-resonance tuning of the latter. If antenna impedance is to be matched with wave impedance of unknown-length conductor, antenna loss resistance is deliberately increased. EFFECT: reduced power requirement. 13 cl, 11 dwg
