| 摘要 |
An antenna suitable for mounting upon vehicles, vessels or aircraft for communication via satellites comprises a conductive ground plane and a radiator element in the form of a conductor helically wound to define a frusto-conical shape with the ground plane as its base. The conductor may be formed upon a dielectric substrate in the shape of a truncated cone. The dimensions of the antenna element are selected so that the pitch angle of the radiator element varies between a minimum of about 6 degrees and a maximum of about 8 degrees. The required pitch angle may be achieved when the cone angle of the frusto-conical shape is between 5 degrees and 20 degrees and the mean diameter of the frusto-conical shape is between 0.3 and 0.47 of a mean operational wavelength predetermined for the antenna. The length of the radiator element is selected to be the minimum needed to sustain a wave. Optimum performance with compact size is attained when the ground plane is about two thirds of the operational wavelength, the cone angle is about 10 degrees and the maximum diameter of the frusto-conical shape is equal to about one half of the wavelength.
|
