| 摘要 |
PURPOSE:To obtain an antenna which features a low cast-up angle as well as high efficiency even with a small altitude by folding once the antenna lowered down vertically and then folding down again. CONSTITUTION:Lead wire W is lowered down from top point A and folded upward at middle point C to be then folded again at point D down onto the ground for feeding. When this wire is excited by transmitter S, the current which sets the nodes at points A and E rides on the wire. In this case, the current featuring the same amplitude and opposite phase flows the distance between points B and C and the distance between points C and D. Thus the current distribution of this antenna becomes identical to the antenna featuring so-called cast-up angles of 0.53-0.63lambda. In case the area between A and B points and the area between C, D and E points are set to about 0.08lambda and 0.25lambda respectively, the best value can be obtained to reduce the cast-up angle. |
