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制造一个具有两个以上螺旋臂的天线,把这些臂对称地连接起来,使天线轴的辐射场得到抑制,这样就能由平衡等角螺旋天线得到圆锥波束。如果参数选得适当,锥束的角度是可以控制的,能使角度限制到逼近方位(θ=90°)平面的地方。具有四个对称间隔臂的天线,能在方位平面得到全向圆极化复盖在3分贝之内的辐射图。接到50欧姆同轴电缆上,在整个辐射图带宽内,天线的驻波比小于2—1。四臂式的仍保持基本圆锥对数螺旋天线的宽频带特点,其复盖范围是至今为止任何窄带天线所难以达到的。
Making an antenna with more than two helical arms, the arms are symmetrically connected so that the radiation field of the antenna shaft is damped so that a conical beam can be obtained from a balanced equiangular helical antenna. If the parameters are properly chosen, the cone beam angle can be controlled to limit the angle to a position approaching the azimuth (θ = 90 °) plane. Antenna with four symmetrically spaced arms provides an omnidirectional circularly polarized radiation pattern within 3 dB at the azimuthal plane. On a 50 Ohm coaxial cable, the antenna’s VSWR is less than 2-1 over the entire radiation pattern bandwidth. The four-arm style still maintains the broadband characteristics of a basic cone-logarithmic spiral antenna, which is not covered by any narrow-band antenna so far.