Title: Directional annular slot antenna

• Summary
• Claims
• Description
• View all

Abstract: This cavity-backed top-loaded annular slot directional antenna is particularly well suited for radio direction-finding applications. Its unique properties allow it to be flush mounted for camouflage use with three or more symmetrical outputs which may be sampled continually. Each output has a symmetrically related unidirectional beam pattern and is nearly constant in impedance. The radio frequency voltages at these outputs are symmetrically phase related, and when combined they produce a circular pattern. All of the antenna elements are in a single structure and the combined outputs are extremely uniform, thus producing reliable patterns such that amplitude comparison for radio direction-finding purposes will be of good accuracy. A single cardioid pattern can be obtained by simply terminating the other ports in a matched load. In this form the antenna would be well suited for use as one antenna in a large aperture array. A second or third antenna of the same type but different size may be installed concentric with the first to extend the range. The frequency bandwidth ratio of 1000 to 1 range is determined at the low frequency limit by the symmetry of the construction and the gain of the system, and at the high frequency limit when the diameter of the annular slot approaches one half wavelength.


Do you think this is a good invention? Vote now: