| 摘要 |
One group of eight electrical leads (F) is on an outer cylindrical surface, the radius of which is equal to around 0.2 wavelengths calculated at the centre of the lower half of the area frequency range. The leads are distributed parallel to each other, and pref. evenly, with a length slightly more than half a wavelength (a quarter wavelength in the case of a monopole). The remaining leads (G) are fitted on an inner cylindrical surface, the radius of which is also equal to approx. 0.2 wavelengths, but calculated at the centre of the upper half of the aerial (A) frequency range. The length of each lead in this second group is identical to that in the first group. All leads are divided at one or more points, division being capable of being short-circuited using a change-over device. An alternative version has the straight electrical leads fitted parallel to each other on only a part of the cylindrical surfaces corresp. to a 30 degree sector. The leads, using support arms and a rotator may be rotated around the central axis of the aerial from one angular position to another. Both the change-over device and the rotator may be remote-controlled from a radio receiver. (Provisional basic advised week 86/44) |
