Patent Publication Number: US-2011050521-A1

Title: Wideband antenna system for garments

Description:
RELATED APPLICATIONS AND TECHNICAL FIELD 
     This application is a continuation of U.S. patent application Ser. No. 12/118,957, filed May 12, 2008, which is a continuation of U.S. patent application Ser. No. 11/210,978 filed 24 Aug. 2005, which claims priority to U.S. Provisional Patent Application Ser. No. 60/603,882, filed Aug. 24, 2004, the entire contents of all of which application are incorporated herein by reference. This application is also a continuation-in-part of U.S. Patent Application Ser. No. 11/778,734 (FRTK-1CN6) filed 17 Jul. 2007, which is a continuation of U.S. Patent Application Ser. No. 10/243,444 (FRTK-1CN5) filed 13 Sep. 2002, which is a continuation of U.S. application Ser. No. 08/512,954 (FRTK-1) filed 09 Aug. 1995, now issued as U.S. Pat. No. 6,452,553; this application is also a continuation-in-part of U.S. patent application Ser. No. 11/390,323 (FRTK-3CN2CN) filed 27 Mar. 2006, which is a continuation of U.S. patent application Ser. No. 10/287,240 (FRTK-3CN2) filed 04 Nov. 2002, which in turn is a continuation of U.S. patent application Ser. No. 09/677,645 (FRTK-3CN) filed 03 Oct. 2000, which in turn is a continuation of both U.S. patent application Ser. No. 08/967,375 (FRTK-1CN4) filed 07 November 1997 and U.S. patent application Ser. No. 08/965,914 (FRTK-3) filed 07 Nov. 1997, issued as U.S. Pat. No. 6,127,977 (3 Oct. 2000); this application is also a continuation-in-part of U.S. patent application Ser. No. 11/867,284 (FRTK-6CN2) filed 04 Oct. 2007, which is a continuation of U.S. patent application Ser. No. 11/327,982 (FRTK-6CN) filed 09 Jan. 2006, which is a continuation of U.S. patent application Ser. No. 10/971,815 (FRTK-6) filed Oct. 22, 2004 now issued as U.S. Pat. No. 6,985,122, which claimed priority to U.S. Provisional Patent Application Ser. No. 60/513,497, filed Oct. 22, 2003. 
     This application is also related to the following U.S. application, of common assignee, and the contents of which are incorporated herein in their entirety by reference: “Antenna System for Radio Frequency Identification,” U.S. patent application Ser. No. 10/971,815 (FRTK-6) filed 22 Oct. 2004. 
     This disclosure relates to antenna systems and, more particularly, to wideband antennas that are incorporated into garments. 
    
    
     BACKGROUND 
     Antennas are used to typically radiate and/or receive electromagnetic signals, preferably with antenna gain, directivity, and efficiency. Practical antenna design traditionally involves trade-offs between various parameters, including antenna gain, size, efficiency, and bandwidth. 
     Antenna design has historically been dominated by Euclidean geometry. In such designs, the closed area of the antenna is directly proportional to the antenna perimeter. For example, if one doubles the length of an Euclidean square (or “quad”) antenna, the enclosed area of the antenna quadruples. Classical antenna design has dealt with planes, circles, triangles, squares, ellipses, rectangles, hemispheres, paraboloids, and the like. 
     With respect to antennas, prior art design philosophy has been to pick a Euclidean geometric construction, e.g., a quad, and to explore its radiation characteristics, especially with emphasis on frequency resonance and power patterns. Unfortunately antenna design has concentrated on the ease of antenna construction, rather than on the underlying electromagnetics, which can cause a reduction in antenna performance. 
     Antenna systems that incorporate a Euclidean geometry include man-portable communication antennas such as monopole antennas. Typically these types of antennas include a wire or rod that may be extended to a deployed position that is located above the antenna carrier&#39;s head. As such, these extendable antennas may provide a visual signature that may disclose the location of the person carrying the antenna (such as a soldier in the field). Additionally, these antennas implement a monopole design that typically exhibit a narrow instantaneous bandwidth. 
     SUMMARY OF THE DISCLOSURE 
     In accordance with an aspect of the disclosure, a portable antenna system includes an antenna that is substantially defined by one or more portions that include electrically conductive self-similar extensions. The system also includes an article of clothing in which the antenna is attached to a surface of the article of clothing such that electrically conductive self-similar extensions extend across the surface of the article of clothing. 
     In one embodiment, the self-similar extensions may include two or more angular bends. The system may further include a co-planar feed connected to the antenna for transmitting and/or receiving electromagnetic signals through the antenna. Each self-similar extension may incorporate a fractal geometry. Furthermore, the antenna may transmit and/or receive electromagnetic energy across a spectral bandwidth that is defined by a ratio of at least 5:1. The system may also include a dielectric plate to which the antenna may be mounted. The dielectric plate may capable of deflecting projectiles. The antenna may be mounted to various locations on clothing. For example, the antenna may be mounted on an internal clothing layer or to an exterior surface of the article of clothing. Various articles of clothing may be used, for example, the article of clothing may be a vest. 
     In accordance with another aspect, a portable antenna system includes an antenna that is substantially defined by one or more portions that include electrically conductive self-similar extensions. The portable antenna system also includes a pouch, in which the antenna is contained. The pouch is also configured for mounting to a clothing surface. 
     In one embodiment, the system may further include a plate upon which the pouch is positioned such that the plate separates the antenna from the body of a person wearing clothing that includes the clothing surface. The self-similar extensions may include two or more angular bends. The system may also include a co-planar feed that is connected to the antenna for transmitting and/or receiving electromagnetic signals. Each self-similar extension may incorporate a fractal geometry. The pouch may include a layer of foam dielectric material or a layer of solid dielectric material. The pouch may include a fibrous dielectric material such as Tyvek™. The plate may include a projectile deflecting material. 
     In accordance with another aspect, a portable antenna system includes an antenna that is substantially defined one or more portions that include electrically conductive self-similar extensions. The system also includes a plate in which the antenna is mounted upon, and a garment in which the plate is attached to a clothing surface included in the garment. 
     In one embodiment, the plate may include a projectile deflecting material and/or a dielectric material. The garment may be a vest. The plate may be attached to a surface of the garment such that when worn, the antenna extends across the back of the person wearing the garment. Each self-similar extension may incorporate a fractal geometry. The antenna may transmit and/or receive electromagnetic energy across a spectral bandwidth that is defined by a ratio of at least 5:1. 
     Additional advantages and aspects of the present disclosure will become readily apparent to those skilled in the art from the following detailed description, wherein embodiments of the present invention are shown and described, simply by way of illustration of the best mode contemplated for practicing the present invention. As will be described, the present disclosure is capable of other and different embodiments, and its several details are susceptible of modification in various obvious respects, all without departing from the spirit of the present disclosure. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as limitative. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagrammatic view of a wideband antenna mounted to a garment. 
         FIG. 2  is a diagrammatic view of the wideband antenna shown in  FIG. 1 . 
         FIG. 3  is a diagrammatic view of a pouch that holds the wideband antenna and may be mounted to the garment shown in  FIG. 1 . 
         FIG. 4  is a diagrammatic view of wideband antenna embedded into a projectile deflecting plate that is mounted on a garment. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Referring to  FIG. 1 , an antenna  10  is mounted conformal to a surface of a garment. In particular, antenna  10  is mounted to the back of a vest  12 , however, in other arrangements the antenna  10  may be mounted to other types of garments such as shirts, coats, parkas, etc. By mounting antenna  10  to the back of vest  12 , a fully integrated antenna is provided for various applications such as combat wear for military personnel. In some arrangements antenna  10  may be incorporated into a military “flak” vest or other similar military clothing known in the art for protecting soldiers in hazardous situations. Typically a flak vest is produced from light-weight material and includes conducting regions formed from a metalized cloth. Such cloth may be formed of a copper coated polyester fabric that is commercially available from Flectron Metalized Materials of St. Louis, Mo. However, any materials known in the art of clothing design and tailoring may be used to produce vest  12 . 
     In this particular implementation, due to materials and production procedures, antenna  10  is opaque at visual wavelengths. However, in other implementations, antenna  10  may be substantially transparent at wavelengths in the visual portion of the electromagnetic spectrum. To mount antenna  10  conformal to vest  12 , the antenna predominately extends in two dimensions (i.e., length and width) and is relatively thin to provide flexibility in movement. Rather than mounting antenna  10  directly to the outer surface of vest  12 , the antenna may be embedded within one or more cloth layers of the vest. Some of these layers may be designed for particular capabilities, such as a bullet-proof layer or other types of projectile (e.g., flak) defection. For example, antenna  10  may be partially or fully embedded in one or more dielectric layer that are incorporated into the vest for bullet and/or flak deflection. A portion or all of this dielectric material may include one or more layers of foam or solid dielectric material. These layers of dielectric material may further be partially or fully embedded within another material. For example, antenna  10  may be embedded in a dielectric plate that is then wrapped around a fibrous dielectric material such as Tyvek®, which is produced by Dupont of Wilmington, Del. 
     Rather than incorporating antenna  10  into the clothing material of vest  12  (or other type of clothing article), the antenna may be incorporated into a pouch or other similar article capable of holding the antenna. By using a pouch, a person such as a soldier can position the antenna on various locations on his or her person. For example, a soldier may position the pouch on his chest or on his back to provide appropriate signal transmission and/or reception performance with other troops, a base, etc. 
     Along with being incorporated into an article of clothing or a pouch, antenna  10  is designed with a self-similar geometry that provides broad frequency coverage for signal transmission and/or reception. In general the self-similar shape is defined as a fractal geometry. Fractal geometry may be grouped into random fractals, which are also termed chaotic or Brownian fractals and include a random noise components, or deterministic fractals. Fractals typically have a statistical self-similarity at all resolutions and are generated by an infinitely recursive process. For example, a so-called Koch fractal may be produced with N iterations (e.g., N=1, N=2 , etc.). One or more other types of fractal geometries may also be incorporated into the design of antenna  10 . 
     By incorporating the fractal geometry into electrically conductive and non-conductive portions of antenna  10 , the length and width of the conductive and non-conductive portions of the antenna is increased due to the nature of the fractal pattern. However, while the lengths and widths increase, the overall footprint area of antenna  10  is relatively small. By providing longer conductive paths, antenna  10  can perform over a broad frequency band. For example, the size reduction (relative to a wavelength) for the lowest frequency of operation approximately has a ratio of approximately 15:1 to 20:1. 
     Antenna  10  provides wideband frequency coverage for transmitting and/or receiving electromagnetic signals. For example, bandwidths ratios of 5:1 or larger may be supported by antenna  10 . For this lower ratio (i.e., 5:1) antenna  10  may perform at frequencies within a broad frequency band, for example, of approximately 3000 Mega Hertz (MHz) to 15,000 MHz. However, it should be appreciated that performance within other frequency bands may be achieved. Thus, antenna  10  is capable of transmitting and receiving electromagnetic signals over a broad frequency range. 
     Referring to  FIG. 2 , antenna  10  is connected to a transceiver  14  over a conductor  16  (e.g., a cable, conducting trace, wire, etc.). By connecting to antenna  10 , transceiver  14  may send signals to the antenna for transmission or receive signals collected by the antenna. Typically to send and receive signals (and improve the gain of antenna  10 ), transceiver  10  includes a low noise amplifier (LNA) and a power amplifier (PA). To connect conductor  16  to antenna  10 , a co-planar feed  18  is electrically connected to the antenna that also provides wideband performance. In some arrangements, a matching network is included in co-planar feed  18  to reduce signal drop-outs (known as “suckouts”) that are located within particular portions of the spectrum. Various techniques known to one skilled in the art of electronics and antenna system design may be implemented to connect connector  16  to antenna  10 . For example, an electrically conductive epoxy may be used to provide an adhesive connection with appropriate electrical conductivity. Additionally, in some embodiments other electromagnetic and electronic devices and components may be connected to co-planar feed  18 . For example, a power divider may be connected between conductor  16  and co-planar feed  18 . 
     In this exemplary fractal antenna design, antenna  10  includes an electrically conductive portion and a non-conductive portion. In particular, antenna  10  includes four sections  20 ,  22 ,  24 ,  26  that include electrically conductive and non-conductive portions that implement a self-similar pattern (e.g., a fractal geometry). Both the conductive and non-conductive portions include extensions that include multiple angular bends to incorporate the self-similar pattern. In this example, each extension includes at least two angular bends. However, in other embodiments more angular bends may be incorporated to produce a similar fractal geometry or a different type of self-similar pattern. 
     In addition to incorporating a self-similar pattern into the conductive and non-conductive extensions, one or more self-similar patterns may be incorporated into the individual extensions. In this exemplary design, triangular holes are cut into two extensions  28  and  30  that are respectively included in section  22  and  26  of antenna  10 . Along with being distributed throughout each extension in a self-similar manner, each individual triangular hole may implement a fractal geometry. 
     Various types of conductive materials may be used to produce the electrically conductive portion (i.e., self-similar extensions) of antenna  10 . For example, various types of metallic material such as metallic tape, metallic paint, metallic ink or powder, metallic film, or other similar materials capable of conducting electricity may be selected. In this particular example, the electrically conductive portion of antenna  10  is produced from an electrically conductive coating that covers a non-conductive substrate. To produce the shape of the self-similar extensions, a laser or other type of cutting device may be used to ablate the conductive coating and from the non-conductive substrate. 
     By exposing portions of the non-conductive substrate, a boundary of the outer-most self-similar extensions is defined by a portion of the substrate. Additionally, exposed segments of the substrate define boundaries of the self-similar extensions. Various types of non-conductive materials may be used as a substrate to define the boundaries of the conductive portions of antenna  10 . For example, these materials may include insulators (e.g., air, etc.), dielectrics (e.g., glass, fiberglass, plastics, etc.), semiconductors, and other materials that impede the flow of electricity. 
     In some embodiments, the non-conductive portions of antenna  10  are produced from a high quality plastic or fiberglass that is structurally sturdy and may be processed (e.g., shaped) relatively quickly. Along with impeding current flow, the non-conductive material also typically provides structural support to the conductive portion of antenna  10 . To provide such support, the non-conductive materials may include materials typically used for support and/or re-enforce other materials. To protect antenna  10  (and provide structural support), a visually transparent (or semi-transparent) material may cover the conductive and non-conductive portions of the antenna. For example, both sides of antenna  10  may be covered by a transparent laminate that is applied with a thermal transfer. The electrically conductive portion and the non-conductive may also be cover by similar or dissimilar material. For example, one laminate may be used to cover the conductive portion of antenna  10  while another laminate is used to cover the non-conductive portion. These different laminates may be used to approximately match the optical appearance of both portions. Multiple layers of materials may also be used to cover the portions of antenna  10 . For example, one layer of laminate may be applied to the electrically-conductive portions of antenna  10  and two or more layers of laminate may be applied to the non-conductive portions to match the optical appearances of the entire antenna. 
     In this exemplary design, the four portions  20 - 26  are configured to provide a dipole response pattern for transmission and/or reception. Alternatively, other antenna designs may be implemented (e.g., a phased array design, etc.) independent or in combination with the dipole design provided in the figure. To expand the frequency coverage of antenna  10 , additional structure may be included in the antenna. For example, one or more conductors (e.g., conductive traces, wires, etc.) may be attached to some (or all) of the self-similar extensions. By including these conductive attachments, the frequency coverage of antenna may be significantly extended. For example, for this exemplary design, the frequency coverage may extend to relatively low frequencies. 
     Antenna  10  may be implemented into various types of antenna systems known to one skilled in the art of antenna design and antenna system design. In one scenario, antenna  10  may be used to transfer radio frequency (RF) signals among people such as military personnel in the field, various types of instillations (e.g., bases, etc.), and/or telecommunication equipment (e.g., wireless telephones, cellular telephones, satellites, etc.). 
     Along with wideband frequency coverage for broadband operations, by incorporating a fractal geometry into antenna  10  to increase conductive trace length and width, antenna losses are reduced. By reducing antenna loss, the output impedance of antenna  10  is held to a nearly constant value across the operating range of the antenna. For example, a 50-ohm output impedance may be provided by antenna  10  across the operational frequency band. 
     Referring to  FIG. 3 , a pouch  32  is shown in which antenna  10  may be inserted. In this particular arrangement, antenna  10  is mounted to a plate  34  that provides structural support. By inserting antenna  10  in pouch  32 , the antenna may be positioned upon various locations of a person that is carrying the pouch. For example, pouch  32  may be attached to the front, back, or side of vest or other type of clothing worn over the torso. Along with wearing pouch  32  external to a piece of clothing or garment, the pouch may be worn under a garment or inserted into between clothing layers of a garment. As mentioned above, various types of material may be incorporated into the pouch. For example, pouch  32  may include one or more layers of foam or solid dielectric material. Fibrous material such as Tyvek™ may also be implemented to cover or wrap around antenna  10 . To attach pouch  32  to a garment of a piece of clothing, various techniques known in the art of clothing design and tailoring may be implemented. For example, Velcro™, straps, hooks, or other similar materials and/or mechanisms may implemented for attaching the pouch. In this exemplary design, one antenna (i.e., antenna  10 ) is inserted into pouch  32 , however, in other implementation, a pouch may be produced that is capable of holding two or more antennas to increase directional coverage. Furthermore, by including electronic equipment such as a power divider in pouch  32 , signals may be split among the multiple antennas. Structural plate  34  may be produced from various materials, for example, the plate may be produced from one or more dielectric materials (e.g., ceramic). In addition to providing structural support, plate  34  may also increase the distance between antenna  10  and the body for the person (e.g., a soldier) that is carrying pouch  32 . For example, pouch  32  maybe positioned on the back of a person such that plate  34  provides a separation distance between antenna  10  and the person&#39;s back. This separation distance increases the electric distance between the person and antenna  10  and thereby reduces the interference effects caused by the person&#39;s body. By decreasing this interference, performance improves for antenna  10 . In this exemplary design, antenna  10  and plate  34  are inserted into pouch  32  that is positioned on a person&#39;s body (e.g., back, chest, etc.). However, in other designs plate  34  may be positioned without the need of pouch  32 . 
     Referring to  FIG. 4 , antenna  10  is embedded in a structural plate  36  that is attached to the back of a vest  38 . Similar to plate  34  (shown in  FIG. 4 ), structural plate  36  also separates antenna  10  from the body of the person wearing vest  38 . By providing this separation, the performance of antenna  10  improves since the separation reduces the interference effects of the person&#39;s body. Also, by implementing various types of material into plate  36 , additionally capabilities may be provided. For example, projectile deflection materials known to one skilled in the art of armor design and personnel protection technology may be incorporated into plate  36 . Various types of bullet deflecting and/or flak deflecting materials may be incorporated into the exterior surface or inner layers of plate  36 . 
     A number of implementations have been described. Nevertheless, it will be understood that various modifications may be made. Accordingly, other implementations are within the scope of the following claims.