Abstract: Thermoplastic welding apparatus and related methods are disclosed. An example method includes providing a smart susceptor between composite parts that are to be joined via thermoplastic welding. The example method includes positioning the composite parts and the smart susceptor on a tooling surface within a cavity of a tooling apparatus and applying a seal to the composite parts and the tooling surface to form a vacuum chamber between the composite parts and the tooling surface at a welding joint of the composite parts; producing a magnetic field at the welding joint. The example method includes providing a vacuum in the vacuum chamber during a welding operation.

Abstract: A system for mitigating radio frequency interference includes a multiple patch antenna array including a multiplicity of patch antenna elements. The multiple patch antenna array is positioned relative to an interfering antenna such that signals from the interfering antenna cause interference with the multiple patch antenna array. The system also includes an auxiliary antenna positioned relative to the multiple patch antenna array. The system additionally includes a device to generate a spatial null in a direction to the interfering antenna from the multiple patch antenna array in response to a first signal from the auxiliary antenna and a second signal from the multiple patch antenna array. The first signal and the second signal are generated in response to a transmitted signal being received by the auxiliary antenna and the multiple patch antenna array. The spatial null permits simultaneous operation of the multiple patch antenna array and the interfering antenna.

Abstract: A system for inductively heating a workpiece may include an induction coil, at least one susceptor face sheet, and a current controller coupled. The induction coil may be configured to conduct an alternating current and generate a magnetic field in response to the alternating current. The susceptor face sheet may be configured to have a workpiece positioned therewith. The susceptor face sheet may be formed of a ferromagnetic alloy having a Curie temperature and being inductively heatable to an equilibrium temperature approaching the Curie temperature in response to the magnetic field. The current controller may be coupled to the induction coil and may be configured to adjust the alternating current in a manner causing a change in at least one heating parameter of the susceptor face sheet.

Abstract: A heating system includes a structure to be heated, and a heating apparatus disposed to heat the structure. The heating apparatus includes a housing member, a plurality of resonant frequency power sources, and a plurality of associated controls. The plurality of resonant frequency power sources are attached to the housing member. The plurality of associated controllers is configured to separately operate the plurality of resonant frequency power sources at resonant frequencies matching heating requirements of the structure.

Abstract: A system for inductively heating a workpiece may include an induction coil, at least one susceptor face sheet, and a current controller coupled. The induction coil may be configured to conduct an alternating current and generate a magnetic field in response to the alternating current. The susceptor face sheet may be configured to have a workpiece positioned therewith. The susceptor face sheet may be formed of a ferromagnetic alloy having a Curie temperature and being inductively heatable to an equilibrium temperature approaching the Curie temperature in response to the magnetic field. The current controller may be coupled to the induction coil and may be configured to adjust the alternating current in a manner causing a change in at least one heating parameter of the susceptor face sheet.

Abstract: A system for mitigating radio frequency interference includes a multiple patch antenna array including a multiplicity of patch antenna elements. The multiple patch antenna array is positioned relative to an interfering antenna such that signals from the interfering antenna cause interference with the multiple patch antenna array. The system also includes an auxiliary antenna positioned relative to the multiple patch antenna array. The system additionally includes a device to generate a spatial null in a direction to the interfering antenna from the multiple patch antenna array in response to a first signal from the auxiliary antenna and a second signal from the multiple patch antenna array. The first signal and the second signal are generated in response to a transmitted signal being received by the auxiliary antenna and the multiple patch antenna array. The spatial null permits simultaneous operation of the multiple patch antenna array and the interfering antenna.

Abstract: A method for detecting and removing spoofing signals may include receiving, by a navigation or communications device, a radio frequency (RF) signal and performing an anti-spoofing assessment to detect a presence of a spoofing signal associated with the RF signal. The method may additionally include generating a replica of the spoofing signal in response to the spoofing signal being detected and subtracting the replica of the spoofing signal from the RF signal to provide a residual non-spoofed signal. The method may further include decoding the residual non-spoofed signal by the navigation or communications device.

Abstract: A part is inductively heated by multiple, self-regulating induction coil circuits having susceptors, coupled together in parallel and in series with an AC power supply. Each of the circuits includes a tuning capacitor that tunes the circuit to resonate at the frequency of AC power supply.

Abstract: Thermoplastic welding apparatus and related methods are disclosed. An example method includes providing a smart susceptor between composite parts that are to be joined via thermoplastic welding. The example method includes positioning the composite parts and the smart susceptor on a tooling surface within a cavity of a tooling apparatus and applying a seal to the composite parts and the tooling surface to form a vacuum chamber between the composite parts and the tooling surface at a welding joint of the composite parts; producing a magnetic field at the welding joint. The example method includes providing a vacuum in the vacuum chamber during a welding operation.

Abstract: A method for detecting and processing signals may include receiving a weak radio frequency (RF) signal by an array of antennas. The method may also include digitally sampling the weak RF signal from each antenna of the array of antennas and storing the digital samples of the weak RF signal from each antenna. The method may additionally include detecting a presence of the weak RF signal. Detecting the presence of the weak RF signal may include determining a correlation between the weak RF signal received by each of the antennas of the array of antennas using the digital samples of the weak RF signal from each antenna.

Abstract: A thermoplastic welding apparatus includes a thermoplastic welding tool, at least one tooling surface in the thermoplastic welding tool, a magnetic induction coil in the thermoplastic welding tool and generally encircling the at least one tooling surface and at least one smart susceptor in the thermoplastic welding tool at the at least one tooling surface. The magnetic induction coil is adapted to generate a magnetic flux field oriented generally parallel to a plane of the at least one smart susceptor.

Abstract: A method for detecting and processing signals may include receiving a weak radio frequency (RF) signal by an array of antennas. The method may also include digitally sampling the weak RF signal from each antenna of the array of antennas and storing the digital samples of the weak RF signal from each antenna. The method may additionally include detecting a presence of the weak RF signal. Detecting the presence of the weak RF signal may include determining a correlation between the weak RF signal received by each of the antennas of the array of antennas using the digital samples of the weak RF signal from each antenna.

Abstract: A method for detecting and removing spoofing signals may include receiving, by a navigation or communications device, a radio frequency (RF) signal and performing an anti-spoofing assessment to detect a presence of a spoofing signal associated with the RF signal. The method may additionally include generating a replica of the spoofing signal in response to the spoofing signal being detected and subtracting the replica of the spoofing signal from the RF signal to provide a residual non-spoofed signal. The method may further include decoding the residual non-spoofed signal by the navigation or communications device.

Abstract: A system for inductively heating a workpiece may include an induction coil, at least one susceptor face sheet, and a current controller coupled. The induction coil may be configured to conduct an alternating current and generate a magnetic field in response to the alternating current. The susceptor face sheet may be configured to have a workpiece positioned therewith. The susceptor face sheet may be formed of a ferromagnetic alloy having a Curie temperature and being inductively heatable to an equilibrium temperature approaching the Curie temperature in response to the magnetic field. The current controller may be coupled to the induction coil and may be configured to adjust the alternating current in a manner causing a change in at least one heating parameter of the susceptor face sheet.

Abstract: A multiferroic element may include a substrate formed on an electrically conductive ground plane. The substrate may be formed from a material having a predetermined elastic modulus. A layer of piezoelectric material may be formed on the substrate. A layer of magnetostrictive material may be bonded to the layer of piezoelectric material. A mechanical strain is created in the layer of piezoelectric material in response to a voltage signal being applied to the multiferroic element. The mechanical strain in the layer of piezoelectric material causes a mechanical strain in the layer of magnetostrictive material to produce a radio frequency magnetic field that is proportional to the voltage signal for generating a radio frequency electromagnetic wave. The predetermined elastic modulus of the substrate is substantially lower than an elastic modulus of the layer of piezoelectric material.

Abstract: A method and apparatus for operating a sensor system. A first wireless signal is transmitted from a base station to a sensor unit. At least a portion of the first wireless signal is changed into power for the sensor unit using a power harvesting unit in the sensor unit. Information is received from a number of sensors associated with the sensor unit. The information is transmitted to the base station using a second wireless signal.

Abstract: A method and apparatus for transmitting wireless signals. An apparatus comprises a stringer having a channel and a waveguide located within the channel. The waveguide is capable of carrying a number of wireless signals.

Abstract: A system for inductively heating a workpiece may include an induction coil, at least one susceptor face sheet, and a current controller coupled. The induction coil may be configured to conduct an alternating current and generate a magnetic field in response to the alternating current. The susceptor face sheet may be configured to have a workpiece positioned therewith. The susceptor face sheet may be formed of a ferromagnetic alloy having a Curie temperature and being inductively heatable to an equilibrium temperature approaching the Curie temperature in response to the magnetic field. The current controller may be coupled to the induction coil and may be configured to adjust the alternating current in a manner causing a change in at least one heating parameter of the susceptor face sheet.

Abstract: A part is inductively heated by multiple, self-regulating induction coil circuits having susceptors, coupled together in parallel and in series with an AC power supply. Each of the circuits includes a tuning capacitor that tunes the circuit to resonate at the frequency of AC power supply.

Abstract: Systems and methods to determine electromagnetic properties are provided. A particular method includes directing electromagnetic energy toward an article under test. The method also includes taking measurements of electromagnetic energy scattered by the article under test. The method further includes determining expected baseline values of at least one electromagnetic property of the article under test. The expected baseline values are based on electromagnetic energy scattered by a control article. The method also includes determining output data based on a difference between the expected baseline values and characteristic values of the article under test determined based on the measurements of electromagnetic energy scattered by the article under test. The output data includes values indicative of inhomogeneous distribution of an electromagnetic property of the article under test.