BROADBAND CORNUCOPIA-TYPE ANTENNA SYSTEM
First Claim
1. A broadband antennA for electromagnetic radiations comprising an antenna element having an arcuate central axis, a lateral closed surface about said axis, a feed point termination located at one end of said closed surface and situated a predetermined distance above a conductive ground plane, an end termination located at the opposite end of said closed surface and connected to said ground plane, said lateral closed surface being diverged outwardly from said feed point termination to said end termination, means for coupling said feed point termination to a source of electromagnetic energy, and a terminating transmission line and capacitance means coupled together in series to said lateral closed surface intermediate said feed point end termination and said end termination for tuning said antenna element to a predetermined operating frequency.
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Abstract
The present invention describes a broadband, low-profile circularly polarized antenna, primarily for airborne applications which has a substantially omnidirectional radiation characteristic in the horizontal plane. The form factor of the antenna comprises a cornucopia-shaped element having an arcuate surface which is defined by a plurality of polynomial line segments and which diverges from one terminal end to the other.
11 Citations
5 Claims
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1. A broadband antennA for electromagnetic radiations comprising an antenna element having an arcuate central axis, a lateral closed surface about said axis, a feed point termination located at one end of said closed surface and situated a predetermined distance above a conductive ground plane, an end termination located at the opposite end of said closed surface and connected to said ground plane, said lateral closed surface being diverged outwardly from said feed point termination to said end termination, means for coupling said feed point termination to a source of electromagnetic energy, and a terminating transmission line and capacitance means coupled together in series to said lateral closed surface intermediate said feed point end termination and said end termination for tuning said antenna element to a predetermined operating frequency.
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2. The invention as defined by claim 1 wherein said capacitance means comprises a variable capacitor and a means coupled to said variable capacitor for effecting a predetermined capacitance value for a selected operating frequency.
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3. The invention as defined by claim 2 wherein said means for effecting a predetermined capacitance value comprises an electrical motor having a shaft coupled to said variable capacitor and additionally including means for controlling said motor means to effect a capacitor setting between two limit stops.
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4. The invention as defined by claim 13 wherein said means for controlling said motor means comprises a pair of mechanically actuated switches located a predetermined distance away from one another, a threaded shaft coupled to said motor means and driven thereby, a pair of notched nuts threadably engaged on said threaded shaft and adapted to be respectively moved into contact with said pair of switches for actuation of said switches to effect a first and a second limit stop, and a detent element located adjacent said pair of notched nuts and being in mechanical engagement therewith for preventing rotation thereof so as to effect a linear movement along said threaded shaft when said shaft is driven by said motor.
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5. The apparatus as defined by claim 3 and additionally including selsyn motor means coupled to said threaded shaft for providing an electrical readout of the mechanical setting of said variable capacitor.
Specification