Abstract:
An antenna capable of being joined to an antenna feed perpendicular to a ground plane includes a conductive radiator and a cylindrical shell. The conductive radiator is tubular and has a longitudinal slot along the entire length thereof. The slot is parallel to the radiator's axis. The antenna feed can be connected across the slot. A cylindrical shell of a uniaxial dielectric material is provided outside and spaced apart from the conductive radiator and extends beyond ends of the conductive radiator. The cylindrical shell electrically contacts the ground plane. The shell is made from a material having a dielectric tensor with high impedance in the axial direction. This antenna gives enhanced bandwidth over ordinary slotted antennas. The shell can be applied to preexisting antennas.
Abstract:
An antenna includes a polymer coating having a VLF/LF element and an HF/VHF element embedded therein. A blocking choke is interposed between the VLF/LF element and the antenna feed t block HF/VHF signals. Small chokes are regularly positioned on the VLF/LF element to eliminate resonances caused by mutual capacitance between the elements. Reactive loads are positioned in said HF/VHF element at regular intervals for optimizing performance of the antenna in the HF/VHF radio bands. In further embodiments the antenna is provided as a floating antenna with the elements helically arranged therein.
Abstract:
An antenna capable of being joined to an antenna feed and being positioned perpendicular to a ground plane includes a conductive cylinder having a longitudinal slot. The antenna feed is connected across the slot. A plurality of dielectric rods are provided parallel to the slot with rod being positioned much less than one wavelength of the maximum operating frequency away from adjacent rods. The rods each have a length of at least 25 times its mean diameter is made from a material having a dielectric constant greater than 30. The combination of the conductive cylinder and dielectric rods provides increased bandwidth. A kit for modifying existing antennas is further provided.
Abstract:
An antenna includes a tubular, conductive radiator having a longitudinal slot formed therein from a first end of the conductive radiator to a second end of the conductive radiator. An antenna feed can be joined to the conductive radiator adjacent to and across the slot. An anisotropic plate is positioned a uniform distance from the conductive radiator, centered above the slot. The plate extends beyond the length of the radiator and is electrically insulated therefrom. An anisotropic tube surrounds the plate and radiator. The anisotropic tube is electrically insulated from the plate and radiator. In use, this antenna gives enhanced bandwidth over ordinary slotted antennas. This can also be applied to preexisting slotted antennas for enhanced bandwidth.
Abstract:
An antenna includes a polymer coating having a VLF/LF element and an HF/VHF element embedded therein. A blocking choke is interposed between the VLF/LF element and the antenna feed to block HF/VHF signals. Small chokes are regularly positioned on the VLF/LF element to eliminate resonances caused by mutual capacitance between the elements. Reactive loads are positioned in said HF/VHF element at regular intervals for optimizing performance of the antenna in the HF/VHF radio bands. In further embodiments the antenna is provided as a floating antenna with the elements helically arranged therein.
Abstract:
A buoyant cable antenna system includes an HF antenna section connected to an outboard end of a VLF/LF antenna. With respect to the HF antenna, the VLF/LF appears to be a standard coaxial cable so that the HF antenna can be configured as desired for HF antenna operation. The VLF/LF antenna is comprised of a segment of coaxial cable. The inboard end of the braided outer conductor of the segment of coaxial cable is connected to ground through a capacitor so that the VLF/LF signals are effectively isolated from ground. In this way, VLF/LF currents are induced on the outer braided conductor of the segment of coaxial cable to thereby operate as the VLF/LF antenna.
Abstract:
An antenna capable of being joined to an antenna feed perpendicular to a ground plane includes a monopole extending perpendicularly from the ground plane. The antenna feed is joined to the monopole. An innermost shell is provided about the monopole. The innermost shell is made from a dielectric material having a dielectric tensor with high permittivity in the direction of the monopole axis. An intermediate shell provided outside the innermost shell. The intermediate shell also has dielectric tensor having high impedance in the direction parallel to the monopole axis. An outermost shell is provided having a perimeter approximately equal to the length of the monopole. The outermost shell also has a dielectric tensor with high impedance in the direction of the monopole axis.
Abstract:
Means and methods of remotely powering a plurality of sensor coils are described. The plurality of sensor coils can be inductively coupled to a single, primary coil so as to bias the active circuitry of the sensors. The primary and sensor coils can have a separation on the order of inches, such that the sensors can be mounted exterior to a vessel and the primary coil can be mounted interior to the vessel. In some embodiments, the primary coil can be a wire coil. In other embodiments, the primary coil can be a planar coil pattern etched onto a printed circuit board.
Abstract:
A dual mode antenna can be joined to an antenna feed. The antenna includes a slotted cylinder radiator that can be connected to the first conductor of the antenna feed and an electrically conductive ground plane that can be connected to the second conductor. The radiator axially extends perpendicularly from the ground plane and is electrically insulated therefrom. The first conductor can be joined to the radiator near one side of the slot. A reactive load is joined between the ground plane and the radiator near an opposite side of the slot. The reactive load impedes lower frequencies from the ground plane to the radiator. This allows the radiator to function as a monopole at lower frequencies and a slotted cylinder at higher frequencies.
Abstract:
An antenna for connection to a feed includes a substrate with a conductive ground plane. An emitter is positioned on the top face of the substrate, and the feed is connected to the emitter and ground plane. A spacer is positioned on the substrate above the emitter and one layer of high dielectric constant rods is positioned above the spacer. The rods are positioned in a single plane, coplanar with the emitter, and parallel to the dominant current distribution when the emitter is active. Further layers of spacers and rods can be positioned at a predetermined angle to the rods beneath. A kit is further provided for application of spacers and rods to preexisting antennas.