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Increasing use of high frequencies in RF systems has led to a need to modify and adapt existing antenna structures. Driving antennas at a higher frequency tend to affect directivity and negatively impact the effective range of antennas. Discone antennas (having a base disc supporting a cone) radiate patterns parallel to the disc which is often oriented parallel to the ground. However, increasing the frequency on these antennas changes the elevation pattern such that it is no longer on the plane with the disc. The pattern will hit the ground sooner and thus lower the effective range of the antenna.
Navy researchers have addressed the above with a new discone antenna design with improved directional gain. In this invention, a portion of the EM field that is emitted from the antenna structure is partially slowed or phase-shifted thereby resulting in an improvement of the horizontal gain of the EM field. EM waves are slowed relative to waves traveling through media with relatively lower dielectric constants when passed through media with high dielectric constants.
The figure at right shows one embodiment of the invention in which a dielectric material (113) is formed onto an outer disc portion (115) of a discone antenna on the side oriented towards the flat or rounded-tip of the cone (117). The dielectric material is formed into a triangular annular form with radial/axial grooves (111) formed onto two outer surfaces of the dielectric material not in contact with the disc forming teeth-like protrusions. Other variants of surface shaping can be used to alter waveforms in a preferential direction and reduce reflections.
- Improved antenna gain
- Simple and highly durable design
- US patent 7,940,225; 8,264,417; and 8,692,729 available for license