| 摘要 |
In the case of a spiral antenna having a circular-cylindrical reflector space, circular-cylindrical bodies consisting of material which absorbs electromagnetic radiation are arranged in the reflector space, concentrically with respect to the antenna axis, in order to tune the antenna over a wide frequency range. As an alternative for this, a body consisting of dielectric material, in the form of a circular cone having an envelope line gradient of 45 DEG and whose cone tip is located at the centre of the antenna spiral can also be arranged in the reflector space.
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