| 摘要 |
A multifilar antenna ( 200 ) comprises n spaced antenna filaments, where n is on integer greater than 1; a matching circuit ( 210 ) for matching the characteristic impedance of the antenna to that of a transmitting and/or receiving apparatus; a weighting circuit ( 240 ) for applying respective gain and phase adjustments to signals passed to or from the n filaments; switch means ( 310 ) associated with each filament for selectively altering the electrical length and/or interconnections of the filaments; means for detecting electrical properties of the multifilar antenna with respect to the frequency, polarisation and/or direction of propagation of a signal to be received or transmitted by the multifilar antenna and/or impedance matching of the antenna; and control means ( 230 ), responsive to the detective means, for controlling the operation of the matching circuit ( 210 ), the weighting circuit ( 240 ) and the switch means ( 310 ) to adjust the properties of the multifilar antenna ( 200 ) to suit better a current signal to be received or transmitted. |
