摘要:
A cylindrical antenna includes: a hollow cylinder having a height, an inner radius b, an axis, a cylindrical surface, and two ends; a ground plane on one end of the cylinder; an antenna wire extending from a center of the cylinder at one end on a ground plane along the axis and ending below the height of the cylinder; and a layer of near zero index (NZI) metamaterial surrounding and adjacent to the cylindrical surface.
摘要:
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.
摘要:
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.
摘要:
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.
摘要:
The invention as disclosed is a buoyant cable antenna configured for both VLF/LF and HF signals. A 100 foot antenna element has a low-pass filter assembly positioned at the midpoint of the antenna element to block HF signals. The outboard tip of the antenna element is shorted. In this way, the antenna element appears as a 50 foot open circuit antenna element to HF signals and as a 100 foot shorted antenna element to VLF/LF signals.
摘要:
This invention serves as a method and apparatus for delivering power to a series of remote sensors in an on hull sensor grid for the purpose of biasing the active circuitry on the sensors. It requires no physical connection between the source of power and the sensor. It works by delivering electrical energy across the insulating gap that separates the sensor from the hull by means of a displacement current. In particular, the method and device include a conducting layer interposed between inner and outer decouplers and a ground plane interposed between a bonding layer and the inner decoupler. An application of alternating current to the ground plane will activate the conducting layer and provide power to the sensors at a location of the outer decoupler. The inner decoupler acts as a capacitor and the ground plane further provides an electrical path back to the hull.
摘要:
A segmented patch antenna has a dielectric material substrate, a plurality of primary electrically conductive segments consecutively disposed on the dielectric material substrate and spaced apart so that a portion of the substrate is exposed between any pair of adjacent primary segments, and a layer of dielectric material disposed over the primary segments. Secondary electrically conductive segments are disposed over the layer of dielectric material wherein each secondary segment corresponds to a pair of adjacent primary segments. Each secondary segment overlaps a portion of each primary segment of the corresponding pair of adjacent primary segments to which that secondary segments corresponds. The overlap of each secondary segment with a portion of each primary segment in a pair of adjacent primary segments produces a plurality of capacitive gaps that capacitively couple the primary and secondary segments together to define a single antenna.
摘要:
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.
摘要:
A hybrid cable antenna includes a first cable antenna that is buoyant and unloaded for operation in a lower portion of the high frequency band. At least one second cable antenna is serially and electrically coupled to the first cable antenna. Each second cable antenna is buoyant and loaded for operation in a portion of the high frequency band that is above the lower portion of the high frequency band.
摘要:
The invention as disclosed is of a buoyant cable antenna for use with underwater vehicles having improved bandwidth through the use of discrete distributed loading along the antenna. The buoyant cable antenna is designed with an antenna wire that is divided into N equal length segments of length d/2. A capacitor is coupled between every other segment such that capacitors are separated by a distance d. A shunt inductor is coupled to the antenna wire between the adjoining segments not separated by a capacitor such that the shunt inductors are separated by a distance d. This antenna design provides a substantially improved impedance bandwidth over existing prior art antennas at high frequency without increasing the physical profile of the antenna and without the use of active circuit elements.