Abstract: The principle of small aperture direction finding antenna based on single channel Watson-Watt direction finding technology is introduced. The method of extracting directional angle value by using correlated matching is discussed. The distribution of angle of indication errors with antenna radius-to-wavelength ratio, phase imbalance and noise are studied by simulation. A five-element broadband direction-finding antenna with working frequency of 30 MHz ~ 600 MHz is designed. Verified in open area test site, under the condition of low signal-to-noise ratio, the direction-finding accuracy of each test frequency point based on correlation matching method is better than that of arc tangent function method. When the root mean square error is less than 5 degrees, the antenna direction finding bandwidth expands from 1 octave to 3 octaves.