Designs for wide band antennas with parasitic elements and a method to optimize their design using a genetic algorithm and fast integral equation technique
First Claim
1. A method for producing optimum design specifications for omni-directional, broadband antennas, comprising the following steps:
- providing design criteria for a basic antenna configuration as input to an algorithmic process;
executing said algorithmic process to determine size and position of parasitic elements for combination with said basic antenna configuration to create improved antenna configurations; and
identifying selected of said improved antenna configurations as optimum configurations based on a predetermined combination of selected antenna performance characteristics.
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Abstract
This technology provides a method (application) of an algorithm to facilitate the design of wideband operations of antennas, and the design of sleeve cage monopole and sleeve helix, units. The technology is of interest/commercial potential throughout the audio communications community.
Omnidirectional capabilities and enhanced wideband capabilities are two desirable features for the design of many antenna applications. Designing omnidirectional antennas with wideband capabilities requires rapid resolution of complex relationship among antenna components to yield an optimal system. The invention comprises the use of a genetic algorithm with fitness values for design factors expressed in terms to yield optimum combinations of at least two types of antennas.
Cage antennas are optimized via a genetic algorithm (GA) for operation over a wide band with low voltage standing wave ratio (VSWR). Numerical results are compared to those of other dual band and broadband antennas from the literature. Measured results for one cage antenna are presented.
Genetic algorithms and an integral equation solver are employed to determine the position and lengths of parasitic wires around a cage antenna in order to minimize voltage standing wave ratio (VSWR) over a band. The cage is replaced by a normal mode quadrifilar helix for height reduction and the parasites are re-optimized. Measurements of the input characteristics of these optimized structures are presented along with data obtained from solving the electric field integral equation.
Genetic algorithms (Y. Rahmat-Samii and E. Michielssen, Electromagnetic Optimizations by Genetic Algorithms, New York: John Wiley and Sons, Inc., 1999) are used here in conjunction with an integral equation solution technique to determine the placement of the parasitic wires around a driven cage. The cage may be replaced by a quadrifilar helix operating in the normal mode in order to shorten the antenna. Measurements of these optimized structures are included for verification of the bandwidth improvements.
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Citations
58 Claims
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1. A method for producing optimum design specifications for omni-directional, broadband antennas, comprising the following steps:
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providing design criteria for a basic antenna configuration as input to an algorithmic process;
executing said algorithmic process to determine size and position of parasitic elements for combination with said basic antenna configuration to create improved antenna configurations; and
identifying selected of said improved antenna configurations as optimum configurations based on a predetermined combination of selected antenna performance characteristics. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for designing and producing a sleeve antenna structure characterized by omni-directional capabilities over a generally wide frequency range, comprising:
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defining initial antenna parameters and providing a corresponding range of potential values for selected of said initial antenna parameters;
executing a first iteration of an algorithmic process to generate a population of individual antenna designs, such that selected individual antenna designs of said population of individual antenna designs are assigned a fitness value that characterizes selected performance measures of said individual antenna design;
evaluating said population of individual antenna designs and selecting certain of said individual antenna designs as having an optimum fitness value; and
executing at least a second iteration of said algorithmic process to generate an additional population of individual antenna designs with a corresponding fitness value assigned to selected individual antenna designs of said additional population. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A process for enhancing basic antenna configurations to accommodate ideal operation in a wider frequency band, comprising the steps of:
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providing a design algorithm for use in accordance with said process for enhancing basic antenna configurations as input to said design algorithm;
providing general antenna parameters and a corresponding range of potential values for selected of said general antenna parameters;
specifying the resolution of selected of said general antenna parameters;
performing a first iteration of said design algorithm to generate a population of individual antenna designs, wherein each individual antenna of said population of individual antenna designs is assigned a fitness value that characterizes selected performance measures of said individual antenna design, and wherein selected of said individual antenna designs are characterized as having a sleeve configuration with a central antenna portion surrounded by a plurality of parasitic elements;
evaluating said fitness values of selected of said individual antenna designs to determine which of said antenna designs are characterized by optimum fitness values; and
performing at least a second iteration of said design algorithm to generate an additional population of individual antenna designs, wherein selected of said individual antenna designs are identified as having a most optimum fitness value. - View Dependent Claims (16, 17, 18, 19, 20, 21)
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22. A method for the design of antenna configurations, wherein said antenna configurations are capable of broadband, omni-directional communications operation, comprising:
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providing initial design parameters and a range of values corresponding to selected of said initial design parameters, and wherein said initial design parameters include antenna height and frequency range of operation;
executing a first design algorithm that combines selected of said initial design parameters to generate populations of antenna designs, wherein selected antenna designs of said populations of antenna designs are assigned a calculated performance ranking;
executing a second design algorithm that determines the electric current in selected of said antenna designs of said populations of antenna designs;
maintaining an interactive link between said first design algorithm and said second design algorithm such that selected information can be communicated between said first design algorithm and said second design algorithm; and
evaluating selected antenna designs to determine which of said selected antenna designs are characterized by a most desirable performance ranking for a given set of initial design parameters. - View Dependent Claims (23, 24, 25, 26, 27, 28)
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29. A method for enhancing the design of broadband cage antennas to facilitate functional operation over a generally wider frequency range, said method comprising the following steps:
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providing design criteria for a basic cage antenna configuration and operational conditions thereof;
executing a cage geometry algorithm to generate a plurality of cage antenna designs with improved cage structures that vary from said basic antenna configuration;
assigning a fitness ranking to each of said cage antenna designs that is indicative of selected performance measures of each of said cage antenna designs and that facilitates the characterization of selected of said cage antenna designs as optimum for certain applications. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40)
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41. A method for use in determining the electronic current in onmi-directional antenna designs, comprising:
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defining initial antenna parameters and providing a corresponding range of potential values for selected of said initial antenna parameters;
determining a system of impedance equations to represent the impedance of a curved antenna structure;
reducing the number of unknown variables in said system of impedance equations such that the calculation time to determine said electronic current in said curved antenna structure is significantly reduced; and
computing the electronic current in said curved antenna structure. - View Dependent Claims (42, 43, 45)
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44. An omni-directional sleeve antenna for use in broadband communications applications, comprising:
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a central conductive characterized by a first end and a second end, and wherein said first end is driven at a ground reference plane and said second end is positioned relative to said first end such that said central conductive element extends in a generally perpendicular fashion to said ground reference plane and said first end; and
a plurality of parasitic elements positioned around said center conductive element and extending in a generally perpendicular fashion from said ground reference plane, wherein the distance between each parasitic element of said plurality of parasitic elements and said first end of said central conductive element is generally equivalent and wherein the length of each of said parasitic elements is generally equivalent; and
wherein the combination of said central conductive element with said plurality of parasitic elements yields an antenna structure that operates in a wider frequency range than would said conductive element without combination with said plurality of parasitic elements. - View Dependent Claims (46, 47, 48, 49)
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50. A sleeve cage antenna for use in wide-band communications applications, wherein said sleeve cage antenna is capable of transmitting and/or receiving electromagnetic radiation in an omni-directional fashion, comprising:
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a conductive stalk positioned generally perpendicular to a ground plane and for electrical connection to a transmission medium, wherein said conductive stalk is characterized by a top end that extends away from said ground plane;
a first stabilizing element constructed with a plurality of conductive strips, and wherein selected of said conductive strips extend from a first common location to a plurality of first extended locations, and wherein the length of each selected said conductive strip from said first common location to each selected of said first extended locations is generally equivalent, and wherein said first common location of said first stabilizing element is connected to said top end of said conductive stalk;
a second stabilizing element constructed with an additional plurality of conductive strips, and wherein selected of said conductive strips extend from a second common location to a plurality of second extended locations in the same fashion as said first stabilizing element, and wherein the number of said first extended locations of said first stabilizing element and the number of said second extended locations of said second stabilizing element is the same;
a plurality of cage wire elements for connecting said first stabilizing element to said second stabilizing element and wherein each cage wire element of said plurality of cage wire elements extends from a selected of said first extended locations to a selected of said second extended locations, and wherein the combination of said plurality of cage wire elements, said first stabilizing element and said second stabilizing element form a cage structure for said sleeve cage antenna; and
a parasitic assembly positioned around said cage structure relative to said ground plane, wherein the distances from selected points of said parasitic assembly to said conductive stalk are generally equivalent. - View Dependent Claims (51, 52, 53, 54, 55, 56, 57, 58)
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Specification