METHOD FOR FORMATION OF ANTENNA RADIATION PATTERN AND SPIRAL ANTENNA FOR ITS REALIZATION Russian patent published in 1997 - IPC

FIELD: antennas of centimeter, decimeter and meter ranges with elliptic polarization of radiation, receiving-transmitting systems of radio communication and direction finding, for instance, for communication with man-made satellites of the Earth, with flying vehicles and in transmitting stations. SUBSTANCE: passive cylindrical spiral 4 with direction of winding of turns counter to rotation direction of vector of electric component of electromagnetic wave emitted by active radiator is placed in near zone of active radiator with elliptic polarization of radiation (for example, active cylindrical spiral 1 placed above metal screen). By irradiation of passive cylindrical spiral travelling wave of current is excited in it which phase in each turn depends on distance to active cylindrical spiral 1. Summing of electromagnetic waves of active and passive cylindrical spirals 1 and 4 in far zone forms radiation pattern of antenna. Translation of passive cylindrical spiral in axial direction changes difference of phases between travelling waves of currents in active and passive cylindrical spirals 1 and 4 in each turn and correspondingly difference of phases of radiated fields. Due to it, there occurs amplification or attenuation of summary electromagnetic field in far zone depending on rank of currents excited in spirals. Ranks of main travelling waves of currents are set by design by selection of length of turns of spirals. With length of turn of active cylindrical spiral L_a = (0,7 - 1,05)λ and passive cylindrical spiral L_p ≥ 1,5λ, where λ is length of wave in free space, one observes transformation of radiation pattern of system "active radiator - passive cylindrical spiral" from conical form to omnidirectional and axial. Reciprocating motion of passive cylindrical spiral in this case provides for both manufacture of greater number of spiral antennas with specified radiation patterns and for scanning of radio beam. EFFECT: broadened application field. 5 cl, 4 dwg