A Linear Array Antenna Using Bifilar Helical Elements for Mobile Satellite Communications (Special Issue on Microwave Devices for Mobile Communications)

概要

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In this paper, authors propose a linear array antenna using two bifilar helical antenna elements placed along the helix axis to reduce beam direction movement according to frequency change. The beam direction movement of this proposed array antenna is smaller than that of a conventional bifilar helical antenna. Also, the gain of this proposed array antenna is higher than that of the conventional helical antenna for a cross point angle of radiation patterns at the different transmit and receive (Tx and Rx) frequencies. The conventional helical antenna is suitable for vehicle antennas in mobile satellite communication systems such as the MSAT system because it owns circularly polarized omni-directional radiation pattern and its thin pole form. However, this antenna has a disadvantage that the beam direction in an elevation plane moves according to frequency change. In the proposed array. antenna, the beam direction movement is about 9°smaller than that of the conventional bifilar helical antenna on condition that antenna total length is 4.83λ_0, antenna diameter is O.12λ_0, and frequency change is from O.957f_0 to 1.043f_0 (f_0 is center frequency and λ_0 is free space wavelength at f_0). Also, the Tx and Rx gains of this proposed array antenna at the cross point angle between Tx and Rx beams are about 2 dB higher than that of the conventional bifilar helical antenna on the same condition.
社団法人電子情報通信学会の論文
1996-05-25