Abstract: Hyperfrequency system for remote data transmission of the type comprises at least one reader (L) associated with a plurality of responders (R) with the reader (L) comprising means to generate a hyperfrequency wave which has a certain rectilinear polarization, while each responder (R) is fitted with a rectangular flat antenna for reemission (1) which is capable of receiving said hyperfrequency wave and reemitting it with orthogonal polarization and phase modulation at two stages representing the data to be transmitted to reader (L), characterized in that the phase modulation is achieved by two transistors (Qa, Qb) which are connected respectively to two adjacent corners (a, b) of antenna (1), these two transistors being alternately blocked and saturated at the rhythm of the data to be transmitted, by additional control signals originating in an appropriate processing unit (4) in order to short circuit alternately the corresponding corner of the antenna.