NONROTATING TACAN ANTENNA

摘要

This invention relates to a method of providing 15 cycle modulation in the distribution cavity of a non-rotating Tacan antenna, which antenna radiates a rotating cardioid radiation pattern. The H11 coaxial mode is induced in the cavity by separately injecting a sequential signal on diametrically opposed probes in the transformer by means of a switching device external to the transformer. The signals fed to each probe of a diametrically opposed pair are in phase opposition. This separate signal is obtained by extracting a part of the transmitter output signal or carrier signal prior to the transformer input. The fraction of the input signal is controlled to adjust the percentage of amplitude modulation at the output of the transformer. Prior to the transformer input the carrier signal is also acted upon by a phase compensator for optimizing the relative phase of the carrier and the 15 cycle modulation component. This arrangement permits separate control of the amplitude and phase of the modulation component with respect to the coexisting carrier component.