Antenna with Sum and Error Patterns.
DEPARTMENT OF THE ARMY WASHINGTON DC
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It is the primary object of the present invention to provide a simplified short backfire antenna which is capable of directional radiation having both sum and error patterns in the H-plane. It is a further object of the invention to provide a short backfire antenna having sum and error patterns with improved resolution and gain. This is accomplished with a modified short backfire type antenna utilizing a rimmed metal pan reflector and a smaller disc reflector spaced along a common axis to form a resonant cavity. Three parallel dipoles are positioned between the reflectors, with the center dipole excitation providing a sum pattern in both E- and H-planes, while the outer pair are fed out-of-phase to provide an error pattern having a broadside null in the H-plane. A hybrid circuit may be used in place of the center dipole in conjunction with two in-phase dipoles to achieve the same patterns. The sum pattern amplitude is made to exceed the error pattern only in the angular vicinity of the broadside null to achieve improved resolution and gain equivalent to a larger antenna. For simplicity in construction, an octagonal reflector pan and square shaped disc reflector are utilized. Other objects and advantages will become apparent from the following description in conjunction with the accompanying drawings. Author
- Electrical and Electronic Equipment
- Radiofrequency Wave Propagation