| 摘要 |
PURPOSE:To attain high efficiency at high and low frequency bands and to eliminate the need of a complicated branching filter, by correcting mirror surface coordinates of a main and a subreflecting mirror so that both reflecting mirrors reflect electromagnetic waves much externally. CONSTITUTION:The antenna consists of a main reflecting mirror 3, the 1st horn antenna 1 being the primary radiator for the high frequency band, the subreflecting mirror 2 and a small sperture horn 4 being the primary radiator for the low frequency band. Thus, the antenna acts like a Cassegrain antenna for high frequencies and a parabola antenna for low frequencies. In the virutal primary radiation pattern of the antenna 1, the electric field strength level at the aperture of the reflecting mirror 3 is constant from the center to the outer circumference and the electric field strength is zero up to the outer circumference of the aperture of the antenna 4. The mirror surface coordinates of the reflecting mirrors 2 and 3 are corrected so that they reflect electromagnetic waves much externally. |
