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附图说明图1所示为普通定向天线,第2至4图所示为本发明的两种实例。本发明的详细说明本发明为在抛物镜面焦点装有激励馈源的超短波定向天线。抛物镜面所用激励辐射器大多采用喇叭形辐射器或装有反射器的偶极子。这种激励辐射器的缺点是:一方面随频率的不同波束角变化较大;另一方面只有对较窄
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a general directional antenna, and FIGS. 2 to 4 show two examples of the present invention. DETAILED DESCRIPTION OF THE INVENTION The present invention is an ultrashort wave directional antenna equipped with an excitation feed at the focus of a parabolic mirror. The excitation radiator used for parabolic mirror mostly adopts a horn radiator or a dipole equipped with a reflector. The disadvantage of such an excitation radiator is that on the one hand the beam angle varies widely depending on the frequency; on the other hand only for narrower