Communications: radio wave antennas – Antennas – Slot type
Patent
1979-03-14
1980-10-21
Moore, David K.
Communications: radio wave antennas
Antennas
Slot type
343713, H01Q 1312
Patent
active
042297443
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.
REFERENCES:
patent: 2508085 (1950-05-01), Alford
patent: 2834959 (1958-05-01), Dorne
patent: 3447159 (1969-05-01), Stromswold
Bentley William F.
Luedtke Arthur
Bentley Wm. Ferrel
Moore David K.
The United States of America as represented by the Field Operati
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