Abstract:
Systems and methods for wireless signal communication in flight vehicles are disclosed. In an embodiment, a system includes a first portion that generates a first wireless zone. A second portion is decoupleable from the first portion and generates a second wireless zone. The first wireless zone and the second wireless zone communicate flight-related information while the first portion and the second portion are coupled, and discontinue the communication subsequent to the separation of the first portion from the second structural portion. In another embodiment, a method includes establishing a first wireless zone in a first portion of a flight vehicle, and establishing a second wireless zone in a second decoupleable portion of the flight vehicle. Flight-related information is communicated between the first wireless zone and the second wireless zone while the first portion and the second portion are coupled, and communication is discontinued after decoupling.

Description:
STATEMENT OF GOVERNMENT INTEREST 
       [0001]    This invention was made with United States Government support under Contract number H00006-04-C-0004 with the Missile Defense Agency. The United States Government has certain rights in this invention. 
     
    
     TECHNICAL FIELD 
       [0002]    The various embodiments are generally directed to wireless signal communication in flight vehicles. More particularly, apparatuses, systems and methods for inter-stage signal communications in multistage flight vehicles are disclosed. 
       BACKGROUND 
       [0003]    Contemporary flight vehicles generally include a variety of electronic and electromechanical systems, such as guidance systems, sensor systems or still other systems that are mutually interconnected to cooperatively interact during operation of the flight vehicle. Since the systems are generally physically separated within the structure of the flight vehicle, signal communications between the various interconnected systems generally rely upon signal transmission elements that extend between the various systems. For example, metallic conductors and even optical conductors may be routed throughout the flight vehicle structure to communicate signals between the various interconnected systems. 
         [0004]    Multi-stage missiles are an example of a flight vehicle having a plurality of systems that are electrically interconnected. In general, multi-stage missiles include a number of aligned stages having separate propulsion and propellant systems that provide propulsive thrust for the multi-stage missile during a specified portion of a flight. Each stage may therefore be individually activated (either in a predetermined sequence, or in parallel) to accelerate the vehicle to an intended speed and altitude. When propellant within a stage is exhausted, an in-flight separation of the exhausted stage occurs, generally by means of pyrotechnic devices that can be detonated on command to sever portions of a structural coupling. Staging generally continues until a final stage is activated, depleted of propellant and separated from the flight vehicle. 
         [0005]    During an in-flight separation of an exhausted missile stage from an adjacent and subsequently operative stage, the electrical interconnections between the exhausted stage and the subsequently operative stage are disconnected. Although the aforementioned pyrotechnic devices may be used to sever the electrical interconnections, more commonly, electrical inter-stage connectors are provided. Briefly, the inter-stage connectors are generally separable into mating portions that reliably provide an electrically continuous path through the connector when the mating portions are coupled, and electrically decouple when a specified separation force is applied to the connector. Although the aforementioned inter-stage connectors suitably allow stages to be electrically decoupled, they are generally expensive and undesirably add to the overall weight of the missile. 
         [0006]    Many flight vehicles may further lack sufficient internal space to accommodate signal transmission elements, such as metallic and/or optical conductors. In particular, and with reference still to multi-stage missiles, the internal space within the missile stages is generally severely limited, so that transmission elements are routed in ducts that are positioned external to the stages. Accordingly, an aerodynamic and flight dynamics penalty is incurred by the externally positioned ducts. 
         [0007]    Thus, there are general needs for systems and methods that avoid the use of inter-stage connectors and that also avoid externally positioned ducts to accommodate inter-stage signal transmission elements. 
       SUMMARY 
       [0008]    Systems and methods for wireless signal communication in flight vehicles are generally described. In an aspect, a wireless communication system may include a first portion configured to generate a first wireless zone. A second portion may be configured to be structurally decoupled from the first portion and may be configured to generate a second wireless zone. The first wireless zone and the second wireless zone may be configured to communicate flight-related information between the first portion and the second portion while the first portion and the second portion are coupled, and to discontinue the communication of the flight-related information between the first portion and the second portion subsequent to the separation of the first portion from the second portion. In another aspect, a method may include establishing a first wireless zone in a first portion of a flight vehicle, and establishing a second wireless zone in a second portion of the flight vehicle. The first portion may be decoupled from the second portion of the flight vehicle. Flight-related information may be communicated between the first wireless zone and the second wireless zone while the first portion and the second portion of the flight vehicle are coupled, and the communication of the flight-related information between the first portion and the second portion of the flight vehicle may be discontinued subsequent to decoupling the first portion of the flight vehicle from the second portion of the flight vehicle. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a partial schematic view of a wireless communication system for a flight vehicle, according to the various embodiments; 
           [0010]      FIG. 2  is a partial schematic view of a wireless communication system for a flight vehicle, according to the various embodiments; 
           [0011]      FIG. 3  is a partial schematic view of still another wireless communication system for a flight vehicle, according to the various embodiments; 
           [0012]      FIG. 4  is a partial isometric view of an antenna installation for a flight vehicle, according to the various embodiments; 
           [0013]      FIG. 5  is a plan view of a patch antenna, according to the various embodiments; 
           [0014]      FIG. 6  is a partial cross-sectional view of the patch antenna of  FIG. 5 ; and 
           [0015]      FIG. 7  is a flowchart that will be used to describe a method of wireless communication in a flight vehicle, according to the various embodiments. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    The following description and the drawings sufficiently illustrate the various embodiments to enable those skilled in the art to practice them. Other embodiments may incorporate structural, logical, electrical, process, and other changes. Accordingly, the examples described herein merely typify possible variations. Individual components and functions may be optional, and the sequence of operations may also vary. Portions and features of the various embodiments may be included in, or substituted for, those of other embodiments. Therefore, the various embodiments as set forth in the claims are to be interpreted as encompassing all available equivalents of those claims. 
         [0017]      FIG. 1  is a partial schematic view of a wireless communication system  10  for a flight vehicle  12 , according to the various embodiments. The system  10  includes a first stage  14  that is removably coupled to a second stage  16  by an inter-stage coupling  18 . In general terms, the first stage  14  and the second stage  16  include propulsion systems, propellant storage and other associated devices (not shown in  FIG. 1 ) that are operable to propulsively and sequentially accelerate the first stage  14  and the second stage  16  of the vehicle  12  during flight. The first stage  14  and the second stage  16  are configured to be separated while in flight (e.g., during a staging operation of the flight vehicle  12 ). Accordingly, the inter-stage coupling  18  may include a generally frangible structural member that may include various pyrotechnic devices that may be activated on command to separate the first stage  14  and the second stage  16 . Although  FIG. 1  only shows the first stage  14 , the second stage  16 , and the inter-stage coupling  18 , it is understood that the flight vehicle  12  may include still other additional stages that are coupled by additional inter-stage couplings interposed between the additional stages, and may also include a payload section. Additionally, it is understood that the first stage  14  and the second stage  16  are not necessarily serially coupled, as shown in  FIG. 1 , but may also be coupled in a parallel arrangement (e.g., “side-by-side”), wherein the depicted first stage  14  and the second stage  16  may be ignited simultaneously, such as, for example, during an initial boost stage. 
         [0018]    The first stage  14  may include a first electronics unit  20 , and the second stage  16  may include a second electronics unit  22 . The first electronics unit  20  and the second electronics unit  22  may, in general, include any electronic circuit or system that assists in the operation of the flight vehicle  12 . For example, either (or both) of the first electronics unit  20  and the second electronics unit  22  may include circuits or systems related to a guidance system or a navigational device for the flight vehicle  12 . In addition, the first electronics unit  20  and the second electronics unit  22  may also include still other circuits or systems related to propulsion systems in the respective first stage  14  and second stage  16 , to sensor systems or devices in the first stage  14  and the second stage  16 , or to circuits related to an in-flight separation system operably coupled to the inter-stage coupling  18 . 
         [0019]    The system  10  may also include a first transceiver  24  that is operably coupled to a first antenna  26  that is positioned in the first stage  14 , and a second transceiver  28  that is operably coupled to a second antenna  30  positioned in the second stage  16 . The first transceiver  24  and the second transceiver  28  may be configured to communicate signals with the first electronics unit  20  and the second electronics unit  22 , respectively. The first transceiver  24  and first antenna  26 , and the second transceiver  28  and the second antenna  30 , will be discussed in greater detail below. The first transceiver  24  and the first antenna  26  may define a first wireless zone  32 , while the second transceiver  28  and the second antenna  30  may define a second wireless zone  34 . The first wireless zone  32  and the second wireless zone  34  are configured to exchange wireless signals  37  at least between the first stage  14  and the second stage  16 . The first stage  14  may also include a power supply  36  that may be operably coupled to the first electronics unit  20  and the first transceiver  24  to provide electrical energy to the first electronics unit  20 , the first transceiver  24 , as well as other systems and circuits in the first stage  14  (not shown in  FIG. 1 ). Correspondingly, the second stage  16  may also include a second power supply  38  that may be operably coupled to the second electronics unit  22 , the second transceiver  28 , and other systems and circuits in the second stage  16 . The first power supply  36  and the second power supply  38  may include a storage battery capable of remote activation, such as a thermal battery that becomes operational upon the application of heat received from a heat source. Alternatively, the first power supply  36  and the second power supply  38  may also include rechargeable cells, or even fuel cells, although other known power sources may also be suitable. 
         [0020]    A first umbilical  40  may be removably coupleable to the first stage  14 , and a second umbilical  42  may also be removably coupleable to the second stage  16 . The first umbilical  40  and the second umbilical  42  are generally configured to communicate electrical energy and/or information to the respective first stage  14  and second stage  16  before the flight vehicle  12  is launched, and decoupled from the flight vehicle  12  upon initiation of a launch procedure. Accordingly, the first umbilical  40  may be removably coupled to the first electronics unit  20  so that information, such as launch initiation information, guidance information, or other pertinent information may be communicated to the first electronics unit  20 . The first umbilical  40  may also be removably coupled to the first power supply  36 , so that electrical energy for battery initiation (e.g., to activate a thermal battery), or battery charging may be provided to the first power supply  36 . Correspondingly, the second umbilical  42  may also be removably coupled to the second electronics unit  22  to communicate information to the second electronics unit  22 , and to provide electrical energy to the second power supply  38 . 
         [0021]    Still referring to  FIG. 1 , the first transceiver  24  and the second transceiver  28  may be configured to operate in any one or more frequency bands generally selected from the ultra-high-frequency (UHF) portion, the super-high-frequency (SHF) portion, or the extremely-high-frequency (EHF) portion of the electromagnetic spectrum. Accordingly, the first transceiver  24  and the second transceiver  28  may be specifically configured to operate in one or more of the LS band (less than approximately 1 GHz), the L-band (approximately 1-2 GHz) the S-band (approximately 2-4 GHz), the C-band (approximately 4-8 GHz), the X-band (approximately 8-12 GHz), the Ku-band (approximately 12-18 GHz), the K-band (approximately 18.00-26.50 GHz) and the Ka-band (approximately 26.50-40.00 GHz), although other frequency bands may also be used. In some of the various embodiments, the first transceiver  24  and the second transceiver  28  are configured to operate in the L-band with a center frequency of approximately 1.8 GHz, and a bandwidth of approximately 500 MHz. In some of the various embodiments, the first transceiver  24  and the second transceiver  28  may be configured to encrypt the wireless signals  37  exchanged between the first transceiver  24  and the second transceiver  28  so that communication between the first wireless zone  32  and the second wireless zone  34  is resistant to jamming or interception. For example, the first transceiver  24  and the second transceiver  28  may be configured to communicate the wireless signals  37  using spread spectrum methods that may include frequency-hopping spread spectrum (FHSS), direct-sequence spread spectrum (DSSS), time-hopping spread spectrum (THSS), chirp spread spectrum (CSS), or suitable combinations of the foregoing methods. In some of the various embodiments, the first transceiver  24  and the second transceiver  28  may be configured to communicate digital data at a rate up to approximately 4.2 gigabits per second (Gbps) when operating frequencies greater than X-band (e.g., approximately 8-12 GHz) are used. In some of the various embodiments, a data rate of approximately 20 megabits per second (Mbps) may be used when the operating frequency is within the L-band (e.g., approximately 1-2 GHz). 
         [0022]    The first antenna  26  and second antenna  30  may be configured to transmit and receive the wireless signals  37  in a selected operating band. In some of the various embodiments, the first antenna  26  and second antenna  30  may include a patch antenna. Briefly, and in general terms, a patch antenna includes at least one approximately planar radiating portion that is separated from a generally planar ground plane by a dielectric material. Accordingly, the at least one radiating portion, the dielectric material and the ground plane may be generally integrated into a flexible planar structure that may be applied directly to a surface, such as a selected surface portion of the first stage  14  and the second stage  16 . In some of the various embodiments, the patch antenna may include at least one radiating portion (e.g., a driven element) that is coupled to an antenna feed point (e.g., to an output of one of the first transceiver  24  and the second transceiver  28 ) and may also include one or more passive reflector and director elements that cooperatively impart directivity to a radiation pattern from the patch antenna. Alternatively, the patch antenna may include a plurality of active elements that are excited in different phases, so that the patch antenna also achieves a predetermined radiation pattern. In either case, the first transceiver  24  and the second transceiver  28  may be coupled to the respective first antenna  26  and second antenna  30  by antenna matching networks (not shown in  FIG. 1 ) and/or matching stubs, or other devices operable to match an impedance of the antenna to a feed point impedance. Alternatively, and also in accordance with the various embodiments, the first antenna  26  and second antenna  30  may include other antenna configurations, such as, for example, a monopole blade antenna configured to extend outwardly from a surface portion of the first stage  14  and the second stage  16 . 
         [0023]      FIG. 2  is a partial schematic view of a wireless communication system  50  for a flight vehicle  12 , according to the various embodiments. In the interest of brevity in the discussion that follows, various portions that have been discussed in detail previously may not be discussed further. The system  50  includes a first transceiver  52  positioned in the first stage  14 , and a second transceiver  54  positioned in the second stage  16 . The first transceiver  52  and the second transceiver  54  are configured to provide more than one communications channel. Accordingly, the first transceiver  52  and the second transceiver  54  may be configured to provide a first communications channel  56  (denoted by “A” in  FIG. 2 ) between the first wireless zone  32   a  and a second wireless zone  34   a , and a second communications channel  58  (denoted by “B” in  FIG. 2 ) between a third wireless zone  32   b  and a fourth wireless zone  34   b . To ensure that the first communications channel  56  and the second communications channel  58  are non-interfering, a first antenna  26   a  and a second antenna  30   a  may be suitably positioned on one portion of the first stage  14  and the second stage  16 , while a third antenna  26   b  and a fourth antenna  30   b  may be positioned on another portion of the first stage  14  and the second stage  16 . For example, the first antenna  26   a  and the second antenna  30   a  may be positioned on one side of the first stage  14  and the second stage  16 , while the third antenna  26   b  and the fourth antenna  30   b  may be positioned on an opposing side of the first stage  14  and the second stage  16 , although other physical arrangements of the first antenna  26   a , the second antenna  30   a , the third antenna  26   b  and the fourth antenna  30   b  are possible. Although two communications channels (e.g., the first communications channel  56  and the second communications channel  58 ) are shown in  FIG. 2 , it is understood that, in accordance with the various embodiments, more than two communications channels may be included. 
         [0024]    With reference to  FIG. 1  and  FIG. 2 , wireless communications between the first transceiver  24  and the second transceiver  28  (or the first transceiver  52  and second transceiver  54 ) eliminate the need for electrical inter-stage connectors between the first stage  14  and the second stage  16 . Accordingly, the additional cost and weight associated with inter-stage connectors is avoided. Moreover, the need for external wiring ducts within stages of the flight vehicle  12  is also eliminated, thus avoiding the adverse effects on dynamics of the flight vehicle  12 . Still other features of the various embodiments may be apparent to those skilled in the art. 
         [0025]      FIG. 3  is a partial schematic view of still another wireless communication system  70  for a flight vehicle  72 , according to the various embodiments. The flight vehicle  72  may include a post-separation portion of a multi-stage vehicle, such as one of the first stage  14  or the second stage  16  shown in  FIG. 1  and  FIG. 2 , that may be following an orbital or sub-orbital flight path. The communication system  70  may include a transceiver  74  that may be operably coupled to a first antenna  76  configured to communicate signals  78  to a ground station  80 . The transceiver  74  may also be operably coupled to a second antenna  82  configured to communicate signals  84  to a satellite  86 , which may further transfer signals  88  to the ground station  80 , or to other receiving stations. The transceiver  74  may be coupled to the first antenna  76  and the second antenna  82  through a Wilkinson power divider (not shown in  FIG. 3 ), for example, to divide the output power applied by the transceiver  74  to the first antenna  76  and the second antenna  82 . The first antenna  76  and the second antenna  82  may also include antenna structures configured to achieve a circularly-polarized radiation pattern to generally assist communications between the transceiver  74  and the ground station  80  and/or the satellite  86 . 
         [0026]    The transceiver  74  may be coupled to an electronics unit  90  that may be configured to provide an identifier to the transceiver  74 , which may be further encoded in at least one of the signals  78  and the signals  84  communicated to the ground station  80  and the satellite  86 , respectively. The identifier may include, for example, at least one of an identification of the flight vehicle  72 , a launch date of the flight vehicle  72 , an altitude or position of the flight vehicle  72 , or other pertinent information that may be useful in tracking the post-launch position and identity of the flight vehicle  72 . 
         [0027]    The communications system  70  may also include a power supply  92  to provide electrical energy to the transceiver  74  and the electronics unit  90 . The power supply  92  may include a thermal battery, as discussed in detail above, but may also include a rechargeable battery that may be coupled to an electrical source, such as a photovoltaic (e.g., solar) panel  94 , so that the endurance of the communications system  70  may be extended beyond that typically available from the thermal battery alone. 
         [0028]    Referring still to  FIG. 3 , the communications system  70  provides communications between the transceiver  74  and at least one of the ground station  80  and the satellite  86  so that the flight vehicle  72  may be positively identified while the flight vehicle  72  is following an orbital or a sub-orbital path. Since the identifier, which may be encoded in the signals  78  and/or the signals  84 , may include identification of the flight vehicle  72 , the orbital or sub-orbital path of the flight vehicle  72  may be more conveniently monitored. 
         [0029]      FIG. 4  is a partial isometric view of an antenna installation  97  for the flight vehicle  12 , according to the various embodiments. The installation  97  includes a first patch antenna  98  positioned on the first stage  14 , and a second patch antenna  99  positioned on the second stage  16 . The first patch antenna  98  and the second patch antenna  99  may be positioned proximate to an interface between the first stage  14  and the second stage  16 , such as proximate to the inter-stage coupling  18 . The first patch antenna  98  and the second patch antenna  99  may be configured to provide a directional radiation pattern “D” that is approximately aligned with a longitudinal axis  96  of the flight vehicle  12 , so that close longitudinal coupling between the first patch antenna  98  and the second patch antenna  99  may be achieved. The first patch antenna  98  and the second patch antenna  99  may include a directional array (e.g., an array having a driven element and one or more closely-coupled reflector or director elements) to achieve the directional radiation pattern “D”, or the first patch antenna  98  and the second patch antennal  99  may include a phase-driven array, having different active portions that may be subject to excitation by different phases that are derived from a primary excitation signal. 
         [0030]      FIG. 5  is a plan view of a patch antenna  100 , according to the various embodiments. The patch antenna  100  may include one or more conductive portions  102  positioned on a dielectric substrate  104 . A conductive ground plane layer  106  may substantially underlie the conductive portions  102  and the dielectric substrate  104 , as shown in greater detail in  FIG. 6 . The dielectric substrate  104  may include a variety of flexible polymeric or elastomeric materials, and the one or more conductive portions  102  and the ground plane layer  106  may include relatively thin layers of metallic foils, so that the patch antenna  100  may be conveniently applied to curved surfaces. Alternatively, the patch antenna  100  may be fabricated from a relatively rigid composite and dielectric material having the conductive portions  102  and the conductive ground plane layer  106  electrodeposited or cladded to opposing sides of the rigid composite material. One suitable material having conductive foil cladded onto opposing sides is Rogers RT/DUROID 5870, available from the Rogers Corporation of Chandler, Ariz., although other suitable alternatives exist. A transmission line  108 , such as a coaxial transmission line, may be operably coupled to the one or more conductive portions  102 , and also operably coupled to the ground plane layer  106 . Although  FIG. 5  shows a single transmission line  108  coupled to a single conductive portion  102 , it is understood that other transmission lines  108  may be coupled to other conductive portions  102  and to the ground plane layer  106 . 
         [0031]    According to the various embodiments, the one or more conductive portions  102  may be approximately rectangular, and may be spaced apart by approximately one-half wavelength (relative to free space), and the conductive portions  102  may extend approximately one-half wavelength (relative to the material comprising the dielectric substrate  104 ). In some of the various embodiments, the conductive portions  102  have dimensions of d 1  approximately equal to 0.2 inch, and d 2  approximately equal to 0.25 inch, and are spaced apart on the dielectric substrate  104  by a distance d 3  approximately equal to 0.3 inch, although other dimensions may be used, and depend upon the selected operating frequency. 
         [0032]    With continued reference to  FIG. 5  and  FIG. 6 , the conductive portions  102  may be operably coupled to individual transmission lines  108 , with a selected phase offset applied to the conductive portions  102 . In one of the various embodiments, the conductive portions  102  may be subjected to a phase offset of approximately 180 degrees, although other phase offset values may also be used. 
         [0033]      FIG. 7  is a flowchart that will be used to describe a method  110  of wireless communication in a flight vehicle, according to the various embodiments. At block  112 , a first wireless zone may be established in a first portion of the flight vehicle. At block  114 , a second wireless zone is established in a second portion of the flight vehicle, where the second portion is separably coupled to the first portion. At block  116 , flight-related information may be communicated between the first flight portion and the second flight portion while the first portion and the second portion are coupled. At block  118 , the communication of flight-related information may be discontinued after the first portion is separated from the second portion. 
         [0034]    The Abstract is provided to comply with 37 C.F.R. Section 1.72(b) requiring an abstract that will allow the reader to ascertain the nature and gist of the technical disclosure. It is submitted with the understanding that it will not be used to limit or interpret the scope or meaning of the claims. The following claims are hereby incorporated into the detailed description, with each claim standing on its own as a separate embodiment.