Abstract:
An exemplary sensor for an aircraft includes a sensor mountable within an aircraft and operative to communicate wirelessly communications to a distributed aperture antenna. The sensor is operative to harvest energy from the aircraft to power the sensor.

Description:
FIELD OF INVENTION 
     This invention relates generally to an arrangement of energy harvesting sensors that wirelessly communicate with a distributed aperture antenna. 
     BACKGROUND 
     As known, sensors are often used to collect information. Some sensors sense temperature or vibration of an aircraft, for example. Users monitor aircraft conditions using the sensed information. Collecting information from multiple sensors desirably provides more information about the aircraft than collecting information from a single sensor. However, increasing the number of sensors within an aircraft undesirably adds cost and weight to the aircraft. 
     Sensors are powered to communicate sensed information away from the sensor. Powering and communicating with multiple sensors often requires expensive and heavy wiring. Other sensors are wireless and include a replaceable source of power, such as a battery. Replacing the battery is often difficult due to the sensor&#39;s position within the aircraft. The battery also increases the size and weight of the sensor. Some sensors harvest energy from the aircraft instead of using a wired connection or battery. 
     Antennas are used in wireless communication systems that include wireless sensors. Wireless communications with one of the wireless sensors can disadvantageously interfere with wireless communications with another one of the wireless sensors. Powering the antennas is costly, and the antennas add weight to the aircraft. 
     SUMMARY 
     An exemplary sensor for an aircraft includes a sensor mountable within an aircraft and operative to communicate wirelessly communications to a distributed aperture antenna. The sensor is operative to harvest energy from the aircraft to power the sensor. 
     An exemplary sensor arrangement for an aircraft includes at least one energy harvesting sensor at least partially powered by energy harvested from the aircraft. A distributed aperture antenna is operative to receive wirelessly communications from the at least one energy harvesting sensor. 
     An exemplary method of wireless communication in an aircraft includes harvesting energy from an aircraft, sensing a condition of the aircraft, and communicating the condition using energy from the harvesting step. The method may include a controller communicating with the sensor to configure the sensor, manage the sensor, or both. 
     These and other features of the example disclosure can be best understood from the following specification and drawings, the following of which is a brief description: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  schematically shows an example gas turbine engine. 
         FIG. 2  shows a partial sectional view of another example gas turbine engine having a sensor and antenna arrangement. 
         FIG. 3  shows a perspective view of the  FIG. 2  gas turbine engine. 
         FIG. 4  schematically shows an example sensor and antenna arrangement. 
         FIG. 5  shows a perspective view of an example distributed aperture antenna. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  schematically illustrates an example gas turbine engine  10  including (in serial flow communication) a fan section  14 , a low pressure compressor  18 , a high pressure compressor  22 , a combustor  26 , a high pressure turbine  30 , and a low pressure turbine  34 . The gas turbine engine  10  is circumferentially disposed about an engine centerline X. During operation, the fan section  14  intakes air, which is then pressurized by the compressors  18 ,  22 . The combustor  26  burns fuel mixed with the pressurized air. The high and low pressure turbines  30 ,  34  extract energy from the combustion gases flowing from the combustor  26 . 
     In a two-spool design, the high pressure turbine  30  utilizes the extracted energy from the hot combustion gases to power the high pressure compressor  22  through a high speed shaft  38 , and a low pressure turbine  34  utilizes the energy extracted from the hot combustion gases to power the low pressure compressor  18  and the fan section  14  through a low speed shaft  42 . The disclosed examples are not applicable only to components within the two-spool gas turbine architecture described above and may be used with other architectures such as a single spool axial design, a three spool axial design, and other architectures. That is, there are various types of gas turbine engine components and components within other systems, many of which could benefit from the examples disclosed herein. 
     As shown in  FIGS. 2 and 3 , the example gas turbine engine  10  for an aircraft  48  includes a Full Authority Digital Electric Control (FADEC)  54 , a type of controller, configured to receive wireless communications via a distributed aperture antenna  46  from at least one energy harvesting sensor  50  that senses information from the engine  10 . In this example, the distributed aperture antenna  46  collects wireless signals  52  from the energy harvesting sensor  50  and transfers the signals to the FADEC  54  mounted to the engine  10  or another type of avionics box mounted to another area of the aircraft  48 . The FADEC  54  stores the sensed information from the energy harvesting sensor  50  or, in another example, communicates the sensed information to another portion of the aircraft  48 . 
     Energy harvested from the engine  10  powers the energy harvesting sensor  50 . As known, the engine  10  produces many sources of energy suitable for harvest. In one example, the energy harvesting sensor  50  includes thermoelectrics that convert thermal potential difference into electric potential difference. Other examples include incorporating a piezoelectric portion into the energy harvesting sensor  50  to harvest vibratory energy from the engine  10 . Still other examples of the energy harvesting sensor  50  are powered by static electricity generated by airflow through the engine  10 , pressure differences within the engine  10 , acoustic energy generated by the engine  10 , etc. 
     In this example, the energy harvesting sensor  50  can be configured to sense or monitor various conditions of the engine  10 . Example conditions include engine temperatures, engine pressures, engine speeds, engine vibrations, acoustic fluctuations in the engine, the presence of oil debris within the engine, engine strains, and engine accelerations. The energy harvesting sensor  50  is also removeably mountable with the engine  10 . That is, an operator can reposition the energy harvesting sensor  50  to facilitate monitoring a particular condition of the engine  10 . 
     The example distributed aperture antenna  46  includes at least one aperture  58  within a shield  62  of the distributed aperture antenna  46 . As known, the aperture  58  provides an energy leakage path for the wireless signals  52 . The energy leakage path facilitates wireless communications between the FADEC  54  and the energy harvesting sensor  50 . 
     In this example, the distributed aperture antenna  46  is routed through the engine  10  such that the aperture  58  is positioned near the energy harvesting sensor  50 . The aperture  58  within the distributed aperture antenna  46  provides a more direct path for communicating with the energy harvesting sensor  50  than provided by other areas of the distributed aperture antenna  46 . Because the path is more direct and line-of-sight, the link performs more efficiently than non-line-of-sight communications. The improved efficiency allows effective communications using lower strength signals between the FADEC  54  connected to the distributed aperture antenna  46  and the energy harvesting sensor  50 . As known, using lower strength signals reduces the overall power requirement for wireless communications. 
     Referring now to  FIG. 4 , the example energy harvesting sensor  50  includes a sensor portion  70 , a microprocessor and radio  74 , an antenna  82 , and an energy harvesting power supply  78 . The energy harvesting sensor  50  senses a condition of the engine  10 , and the microprocessor and radio  74  transmit, via the antenna  82 , the sensed information to the FADEC  54  via the distributed aperture antenna  46 . The energy harvesting power supply  78  powers the sensor  50  and the microprocessor and radio  74 . 
     In some examples, the energy harvesting power supply  78  includes an energy storage device  80 , such as a capacitor or a battery that provides power to the sensor  70  during brief time periods requiring high current or during periods low energy harvesting. The energy harvesting power supply  78  can act as a sensor such as a piezoelectric harvesting device for vibration monitoring. 
     The FADEC  54 , or other avionics box, is connected to the distributed aperture antenna  46  by coaxial connection  86 . Other examples utilize different RF transmission line technologies. In this example, the communications at  86  between the FADEC  54  and the distributed aperture antenna  46  are wired communications. 
     Referring now to  FIG. 5  with continuing reference to  FIG. 4 , the example distributed aperture antenna  46  includes the shield  62  surrounding an antenna core  90 . The aperture  58  extends through the shield  62  to the antenna core  90 . Other examples of the aperture  58  do not extend through the shield  62 , such a thinned area of the shield  62  relative other portions of the shield  62 . Both the aperture  58  and the thinned area provide energy leakage paths within the antenna  46  that facilitate communication with the sensor  50 . The position of the energy leakage paths within the antenna  46 , and the routing of the antenna  46 , corresponds to the placement of the sensor  50 . Although the example distributed aperture antenna  46  is described as having a general coaxial structure, other example antennas have differing non-coaxial structures. 
     The wireless signals  52 , or electric fields, emanate from areas of the distributed aperture antenna  46  near the aperture  58 . Provided the level of power provided to the distributed aperture antenna  46  remains consistent, adding more apertures to the shield  62  decreases the signal strength of the wireless signals  52 . 
     Features of this disclosure include using lower strength signals that provide less interference with other wireless communication than higher strength signals when communicating with the FADEC  54 . The wireless link between the FADEC  54  and the energy harvesting sensor  50  is also more efficient than some prior designs. The improved efficiency facilitates utilizing lower signal strengths, provides more flexible options for mounting the energy harvesting sensor  50 , etc. Another feature is varied mountablility of the energy harvesting sensor  50  because less concern need be given to the types of structures that surround the energy harvesting sensor  50 . 
     Additional features of this disclosure include communicating information from energy harvesting sensor  50  to the FADEC  54  using less power than previous arrangements. Another feature includes enhanced signal integrity due to reduced interference between signals from an adjacent energy harvesting sensor due to effectively communicating with wireless signals  52 . Still other features include increasing the density of the energy harvesting sensor  50  within the engine  10  while maintaining signal integrity between the energy harvesting sensor  50  and the distributed aperture antenna  46  and throughout the aircraft  48 . An additional feature of the invention is the ability to reuse certain sections of wireless spectrum, allowing more information to be gathered by the energy harvesting sensors  50 . 
     Although a preferred embodiment has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.