Systems and methods to stir an electromagnetic (EM) field

Systems and methods to stir an electromagnetic (EM) field of an EM reverberation chamber are disclosed. A particular system includes an EM reverberation chamber. The system also includes a transmit antenna and a receive antenna operable to generate an EM field within the EM reverberation chamber. The system further includes a variable charged particle source to stir the EM field by varying introduction of charged particles into the EM field.

FIELD OF THE DISCLOSURE

The present disclosure is generally related to stirring an electromagnetic (EM) field.

BACKGROUND

Electromagnetic (EM) reverberation chambers are used to perform various tests on devices. For certain tests, an EM reverberation chamber subjects a device under test to an EM field. The EM reverberation chamber may include a stirring device to stir the EM field. For example, the EM reverberation chamber may include a movable metal paddle that is moved to stir the EM field.

SUMMARY

Systems and methods to stir an electromagnetic (EM) field of an EM reverberation chamber are disclosed. In a particular embodiment, a system includes an EM reverberation chamber. The system also includes a transmit antenna and a receive antenna operable to generate an EM field within the EM reverberation chamber. The system further includes a variable charged particle source to stir the EM field by varying the introduction of charged particles into the EM field.

In another particular embodiment, a method includes generating an electromagnetic (EM) field in an EM reverberation chamber. The method also includes introducing a plurality of charged particles into the EM reverberation chamber. The method further includes stirring the EM field by varying the plurality of charged particles introduced into the EM reverberation chamber.

DETAILED DESCRIPTION

The features, functions, and advantages that are discussed can be achieved independently in various embodiments disclosed herein or may be combined in yet other embodiments further details of which can be shown with reference to the following description and drawings.

Particular systems and methods described below can be used to stir electromagnetic (EM) fields in EM reverberation chambers. In particular, the systems and methods enable stirring of the EM fields without the use of mechanical stirring devices, such as moveable metal paddles. Avoiding the use of mechanical stirring devices may reduce the cost of the EM reverberation chambers. Additionally, since mechanical stirring devices may be large and may be placed within the EM reverberation chamber, eliminating the mechanical stirring devices may allow more of the EM reverberation chamber to be used or may allow smaller EM reverberation chambers to be used.

Further, particular moveable metal paddles may be designed and placed within the EM reverberation chamber to stir EM fields that have certain characteristics. When the EM field characteristics are changed, the moveable metal paddles may be moved. For example, a step motor may be used to adjust a position of the moveable metal paddle. Such step motors can be expensive. Additionally, when a step motor is used a settling time may be required after moving the moveable metal paddles to allow vibrations and oscillations of the moveable parts to settle before testing is performed. However, the systems and methods described herein enable stirring of EM fields having different characteristics without changing out or relocating equipment, such as moveable metal paddles.

FIG. 1is a diagram of a first particular embodiment of a system to stir an electromagnetic (EM) field of an EM reverberation chamber. The system includes an EM reverberation chamber102having a plurality of antennas, such as a transmit antenna104and a receive antenna106, that may be driven by a radio frequency (RF) amplifier108to generate an electromagnetic field114.

In a particular embodiment, the antennas104,106may be coupled to a network analyzer110. The network analyzer110is responsive to the transmit antenna104and the receive antenna106to take readings of the EM field114within the EM reverberation chamber102. The network analyzer110may be coupled to a computing device112that includes a processor capable of analyzing the EM field114readings to determine particular information about the EM field114. For example, the computing device112may determine whether a desired level of stirring of the EM field114has been achieved. For example, the computing device112may perform statistical analysis of the readings taken by the network analyzer110to determine when the EM field114is stirred and when the stirring level reaches a desired level.

Stirring the EM field114refers to varying the distribution of the EM field114within the EM reverberation chamber102. For example, in a first type of operation, the EM field114may be stirred while readings of the EM field114are taken. This type of operation is sometimes referred to as “mode stirring” or “mode stirred operation”. In another example, in a second type of operation, the EM field114may be stirred between taking readings at different input conditions (e.g., different frequencies or polarizations of the EM field114). The second type of operation is sometimes referred to as “mode tuning” or “mode tuned operation”. In either type of operation, the EM field114may be stirred to average out the distribution of the EM field114within the EM reverberation chamber102over a number of readings.

During operation of the EM reverberation chamber102, the network analyzer110and the computing device112may determine an effect of the EM field114on a unit under test116. By stirring the EM field114while testing the unit under test116, an understanding of how various EM field conditions affect the unit under test116can be determined. For example, the unit under test116may be tested for EM susceptibility at various EM field conditions, such as field strengths, frequencies, polarizations, or any combination thereof.

In a particular embodiment, the EM reverberation chamber102includes an input port122. The input port122is adapted to allow introductions of a plurality of charged particles into the EM reverberation chamber102. For example, the charged particles may be generated by a variable charged particle source, such as a particle accelerator120(e.g., an electron beam gun, a linear accelerator, an ion beam gun, or another particle beam accelerator). The particle accelerator120may project the plurality of charged particles as a charged particle beam124into the EM reverberation chamber102. In a particular embodiment, the presence of the charged particle beam124in the EM reverberation chamber102changes the distribution of the EM field114within the EM reverberation chamber102. For example, when sufficient charged particles are present, the charged particle beam124may act as a conductive surface within the EM reverberation chamber. The charged particle beam124may modify the EM field114in a manner similar to introducing a conductor or conductive surface to the EM reverberation chamber102. In a particular embodiment, by changing the charged particle beam124, modes of the EM field114within the EM reverberation chamber102can be changed enabling mode stirring operation or mode tuning operation of the EM reverberation chamber. The mode stirring or mode tuning may be used to test the effects of the EM field114on the unit under test116.

FIG. 2is a diagram of a second particular embodiment of a system to stir an electromagnetic (EM) field of an EM reverberation chamber. In a particular embodiment, the system illustrated inFIG. 2can include many of the same or similar features as were discussed with reference toFIG. 1. Accordingly, to simplify the description ofFIG. 2, features that may be the same or similar between the system illustrated inFIG. 1and the system illustrated inFIG. 2have been given the same reference numeral. For example, inFIG. 2, the system includes the reverberation chamber102with the transmit antenna104and the receive antenna106coupled to the radio frequency (RF) amplifier108to generated the EM field114. Additionally, the system includes the network analyzer110and the computing device112to sample and analyze the EM field114and the effects of the EM field114on the unit under test116.

In the system illustrated inFIG. 2, the input port122includes or is in proximity to a charged plate130. The charged plate130may include an opening through which a charged particle beam132may be introduced into the EM reverberation chamber102. For example, the charged particle beam132may be projected from the particle accelerator120through or near the charged plate130. In a particular embodiment, when a charge is applied to the charged plate130, the charge modifies the charged particle beam132as a result of charged particles of the charged particle beam132being attracted to or repelled by the charge. The charged plate130may be used to change a distribution of the charged particles within the EM reverberation chamber102. For example, the charged plate may be used to change a focus or a direction of the charged particle beam132. To illustrate, the charged particle beam132may be spread to a broader focus region or narrowed to a finer focus region thereby changing the distribution of the charged particles of the charged particle beam132within the EM reverberation chamber102.

By changing a charge applied to the charged plate130, the charged particle beam132may be controlled to stir the EM field114within the EM reverberation chamber102. For example, before the charge is applied to the charged plate130, the beam may be a substantially straight and narrowly focused beam, such as the relatively narrow, focused charged particle beam124illustrated inFIG. 1. However, after the charge is applied to the charged plate130, the beam may be spread out, or less focused, such as the relatively broad, less focused charged particle beam132illustrated inFIG. 2. Alternatively or additionally, the charged plate130may be used to change a direction of the charged particle beam132within the EM reverberation chamber102. Changing the direction of the charged particle beam132within the EM reverberation chamber102changes the distribution of charged particles in the EM reverberation chamber and may result in stirring of the EM field114.

FIG. 3is a diagram of a third particular embodiment of a system to stir an EM field of an EM reverberation chamber. In a particular embodiment, the system illustrated inFIG. 3can include many of the same or similar features as were discussed with reference toFIGS. 1 and 2. Accordingly, to simplify the discussion ofFIG. 3, features that may be the same or similar between the system illustrated inFIG. 3and the system illustrated inFIG. 1or the system illustrated inFIG. 2have been given the same reference numeral. For example, inFIG. 3, the system includes the reverberation chamber102with the transmit antenna104and the receive antenna106coupled to the radio frequency (RF) amplifier108to generated the EM field114. Additionally, the system includes the network analyzer110and the computing device112to sample and analyze the EM field114and the effects of the EM field114on the unit under test116.

In the system illustrated inFIG. 3, the EM reverberation chamber102includes the input port122that includes or is in proximity to a control element140. The control element140enables variable introduction of a plurality of charged particles into the EM reverberation chamber102from the particle accelerator120. For example, the control element140may turn the particle accelerator120on and off to generate a pulsed charged particle beam142. The cycle or timing of the pulses may be modified to change an effect of the charged particles on the EM field114in order to stir the EM field114. In another example, the control element140may include a shutter or other similar device that blocks or inhibits charged particles from the particle accelerator120from being introduced into the EM reverberation chamber102. More specifically, the particle accelerator120and the control element140may together form a variable charge particle source.

FIG. 4is a diagram of a fourth particular embodiment of a system to stir an EM field of an EM reverberation chamber. In a particular embodiment, the system illustrated inFIG. 4can include many of the same or similar features as discussed with reference toFIG. 1,FIG. 2, orFIG. 3. Accordingly, to simplify the discussion ofFIG. 4, certain features have been given the same reference numeral when those features may be the same or similar between the system illustrated inFIG. 4and the system illustrated inFIG. 1, the system illustrated inFIG. 2, or the system illustrated inFIG. 3. For example, inFIG. 4, the system includes the reverberation chamber102with the transmit antenna104and the receive antenna106coupled to the radio frequency (RF) amplifier108to generated the EM field114. Additionally, the system includes the network analyzer110and the computing device112to sample and analyze the EM field114and the effects of the EM field114on the unit under test116.

In the system illustrated inFIG. 4, the EM reverberation chamber102includes a control element150. The control element150controls the introduction of a charged particle beam152into the EM reverberation chamber102from a charged particle source, such as the particle accelerator120. In a particular embodiment, the control element150is adapted to change an angle of the charged particle beam152introduced into the EM reverberation chamber102. To illustrate, the charged particle beam152may be directed around an interior of the EM reverberation chamber102in a pattern or in a random or pseudo-random manner. In a particular illustrative embodiment, the control element150includes one or more charged plates that are adapted to steer the charged particle beam152. In other embodiments, the control element150includes other devices or apparatus adapted to change the direction of the charged particle beam152. Changing the direction of the charged particle beam152may change a distribution of the charged particles within the EM reverberation chamber102. Therefore, by changing the direction of the charged particle beam152introduced into the EM reverberation chamber102, the EM field114may be stirred, for example, to enable testing of the unit under test116.

In a particular embodiment, the computing device112and the network analyzer110may interact to stir the EM field114. For example, the network analyzer110may take baseline readings of the EM field114before the charged particles are introduced into the EM reverberation chamber102(e.g., as illustrated inFIG. 1). Subsequently, the charged particles may be introduced into the EM reverberation chamber102(e.g., as illustrated inFIGS. 2-4). The network analyzer110may then take a second set of sample readings of the EM field114. The computing device112may analyze the baseline readings and the second set of sample readings of the EM field114to determine whether the EM field114is effectively stirred. When the computing device112determines that the EM field114is not effectively stirred, a characteristic of the charged particles introduced into the EM reverberation chamber102may be changed to achieve stirring of the EM field114. In an illustrative embodiment, the computing device110alternately (e.g., iteratively) performs a statistical analysis of the readings taken by the network analyzer110and varies the charged particles introduced into the EM reverberation chamber102until the statistical analysis indicates that the EM field114is stirred.

FIG. 5is a diagram of a fifth particular embodiment of a system to stir an EM field of an EM reverberation chamber. The system includes an electromagnetic reverberation chamber502having a transmit antenna504and a receive antenna506. The transmit antenna504, the receive antenna506, or both, may be coupled to a radio frequency (RF) amplifier508. The antenna504,506are also coupled to a network analyzer510. The network analyzer510is adapted to take readings of an EM field514between the transmit antenna504and the receive antenna506. The network analyzer510may also be coupled to a computing device512. The computing device512may include a processor and may be adapted to analyze the readings taken by the network analyzer510to determine statistical information regarding the EM field514, the effect of the EM field514on a unit under test516, or both.

In a particular embodiment, the EM reverberation chamber502includes a variable charged particle source. For example, the variable charged particle source may include a plasma source520. In an illustrative embodiment, the plasma source520includes a light array, such as a plurality of florescent lights. For example, the plasma source520may include a first florescent light522, a second florescent light524, a third florescent light526and a fourth florescent light528. Each florescent light522-528is adapted to generate a plasma within the EM reverberation chamber502. The plasma generated by the florescent lights522-528may act as a conductive surface that modifies the EM field514within the EM reverberation chamber502.

The plasma source520may vary the charged particles introduced into the EM reverberation chamber502by changing which florescent lights522-528are powered, an amount of power applied to one or more of the florescent lights522-528, or both. For example, as illustrated inFIG. 5, the florescent lights522-528are shown as off as indicated by an “x” pattern within the florescent lights522-528. However, as illustrated inFIG. 6, the third florescent light526is on. Turning on the third florescent light526changes the distribution of charged particles within the EM reverberation chamber502resulting in a change in the distribution of the EM field514within the EM reverberation chamber502.

In a particular embodiment, the computing device512may control the plasma source520to change power provided to the florescent lights522-528, to change which florescent lights522-528are turned on, to change other characteristics of the florescent lights522-528, or any combination thereof. For example, the plurality of florescent lights522-528of the plasma source520may be powered in different patterns. Thus, the computing device512can vary the introduction of the charged particles into the EM reverberation chamber502from the plasma source520to change the EM field514without the use of any mechanical apparatus (such as a mechanical stirring device).

In a particular embodiment, the computing device512and the network analyzer510may interact to stir the EM field514. For example, the network analyzer510may take baseline readings of the EM field514without any of the florescent lights on (as illustrated inFIG. 5). Subsequently, one or more of the florescent lights522-528may be turned on. For example, the third florescent light526may be turned on (as illustrated inFIG. 6). The network analyzer510may then take a second set of sample readings of the EM field514. The computing device512may analyze the baseline readings and the second set of sample readings of the EM field514to determine whether the EM field514is effectively stirred. When the computing device512determines that the EM field514is not effectively stirred, the plasma source520may be varied, for example, by turning on one or more additional florescent lights522-528, such as the first florescent light522. Alternately, a characteristic of the third florescent light526may be changed. For example, the amount of power supplied to the third florescent light526may be increased or decreased, or a frequency of the power applied to the third florescent light526may be changed. In an illustrative embodiment, the computing device510alternately performs a statistical analysis of the readings taken by the network analyzer510and controls the plasma source520to vary the charged particles introduced into the EM reverberation chamber502(e.g., by changing a characteristic of at least one florescent light522-528) until the statistical analysis indicates that the EM field514is stirred. In this manner, various distributions of charged particles may be introduced into the EM reverberation chamber502. For example, different patterns of the florescent lights522-528may be powered and various power levels or other power characteristics may be provided to the florescent lights522-528.

FIG. 7is a flow diagram of a first particular embodiment of a method of stirring an EM field of an EM reverberation chamber. The method700may include, at702, generating an electromagnetic (EM) field in an EM reverberation chamber. For example, the EM reverberation chamber may include the EM reverberation chamber102discussed with reference toFIGS. 1-4or the EM reverberation chamber502discussed with reference toFIGS. 5 and 6. The method700may also include, at704, introducing a plurality of charged particles into the EM reverberation chamber.

Introducing the plurality of charged particles into the EM reverberation chamber at704may cause stirring; however, in a particular embodiment, the method700also includes stirring the EM field by varying the plurality of charged particles introduced in the EM reverberation chamber, at706. For example, the plurality of charged particles introduced into the EM reverberation chamber may be varied by changing, at708, a location of the charged particles within the EM reverberation chamber. To illustrate, a direction of a charged particle beam may be modified by using a beam steering mechanism (such as a charged plate) to change an angle or distribution of the charged particle beam introduced into the EM reverberation chamber. In another illustrative example of changing a location of the charged particles, different lights of a variable light array may be powered to change a location or a distribution of a plasma introduced into the EM reverberation chamber. In yet another illustrative example, a focus of a charged particle beam introduced into the EM reverberation chamber may be changed using a shutter or another beam focusing mechanism (such as a charged plate).

In a particular embodiment, the plurality of charged particles introduced into the EM reverberation chamber may be changed, at710, by changing an intensity measure associated with the charged particles introduced into the EM reverberation chamber. To illustrate, the intensity measure may be associated with a power level of a charged particle beam or plasma introduced into the EM reverberation chamber. For example, a power level supplied to a florescent light array that generates plasma within the EM reverberation chamber may be modified to change the intensity measure. In another example, an intensity of a charged particle beam generated by a particle beam gun may be modified to change the intensity measure.

The charged particles introduced into the EM reverberation chamber may be varied, at712, by changing a distribution of the charged particles within the EM reverberation chamber. For example, the distribution of the charged particles of the EM reverberation chamber may be modified by changing the focus of a charged particle beam introduced into the EM reverberation chamber. In another example, the distribution of charged particle in the EM reverberation chamber may be modified by changing a direction or angle at which the charged particle beam is introduced into the EM reverberation chamber. In yet another example, the distribution of charged particles within the EM reverberation chamber may be modified by changing an intensity of the charged particle beam or cycling the charged particle beam on and off. In yet another example, the distribution of charged particles within the EM reverberation chamber may be modified using a plasma source by changing a pattern of plasma sources that are powered within the EM reverberation chamber or by changing a power level of one or more of the plasma sources.

In a particular embodiment, the plurality of charged particles introduced into the EM reverberation chamber may be varied, at714, by turning a source of the charged particles on or off. For example, where a plasma source is used a plurality of florescent lights may be powered on or off individually, or as a group, to change the charged particles within the EM reverberation chamber. In another example, a particle accelerator, such as an electron beam gun, may be turned on or off occasionally, periodically, or according to a particular pattern in order to stop and start the introduction of charged particles into the EM reverberation chamber.

In another particular embodiment, the plurality of charged particles introduced into the EM reverberation chamber may be varied, at716, by changing a density of the charged particles within the EM reverberation chamber. In an illustrative embodiment, the density of the charged particles associated with a plasma may be related to power applied to the plasma source, may be related to a number of plasma sources powered within the EM reverberation chamber, or both. For example, where the plasma source includes florescent light bulbs, the power applied to each florescent light bulb may be modified to change the density of the charged particles in the EM reverberation chamber, or the number of florescent light bulbs that are powered may be changed to change the density of the charged particles within the EM reverberation chamber. In another example, the intensity of a charged particle beam generated by a particle accelerator may be modified to change the density of the charged particles in the EM reverberation chamber.

In a particular embodiment, the method includes, at718, modifying at least one parameter associated with the charged particles introduced into the EM reverberation chamber until stirring is achieved. For example, a statistical correlation may be determined with respect to baseline readings taken before the charged particles are introduced into the EM reverberation chamber and one or more sample readings taken after the charged particles are introduced into the EM reverberation chamber. When there is a statistical correlation between the baseline readings and the one or more sample readings (e.g., when a correlation value related to the baseline readings and the sample readings satisfies a predetermined threshold), the EM field may be determined to not be stirred. However, when there is no statistical correlation between the baseline readings and the one or more sample readings (e.g., when the correlation value related to the baseline readings and the sample readings does not satisfy the predetermined threshold), the EM field may be determined to be stirred. When stirring is not achieved, the charged particles introduced into the EM reverberation chamber may be varied and another statistical correlation may be determined. Thus, the method may continue iteratively in this manner until stirring is achieved.

FIG. 8is a flow diagram of a second particular embodiment of a method of stirring an EM field of an EM reverberation chamber. The method800includes, at802, generating an electromagnetic (EM) field in an EM reverberation chamber. The method800may also include, at804, taking a first sample reading of the EM field. For example, a network analyzer (such as the network analyzer110discussed with reference toFIGS. 1-4, or the network analyzer510discussed with reference toFIGS. 5 and 6) may be used to sample the EM field within the EM reverberation chamber.

In a particular embodiment, the method800includes, at806, introducing a plurality of charged particles into the EM reverberation chamber. For example, the plurality of charged particles may be introduced by generating a plasma within the EM reverberation chamber, at808. The plasma may be generated, at810, by turning on at least one florescent light within the EM reverberation chamber.

The method800may also include, at812, stirring the EM field by varying the plurality of charged particles introduced into the EM reverberation chamber. For example, the charged particles introduced into the EM reverberation chamber may be varied by varying the plasma generated in the EM reverberation chamber. The method may include, at814, taking at least one second sample reading of the EM field. A network analyzer may be used to take the second sample reading(s) of the EM field within the EM reverberation chamber. The method may further include, at816, determining a relationship between the first sample reading and the at least one second sample reading.

In a particular embodiment, the method includes, at818, modifying at least one parameter associated with the charged particles introduced into the EM reverberation chamber until a pre-determined relationship between the first sample reading and the at least one second sample reading is achieved. For example, a statistical correlation of the first sample reading and the at least one second sample reading may be determined. When there is a statistical correlation between the first sample reading and the at least one second sample reading (e.g., when a correlation value related to the first sample reading and the at least one second sample reading satisfies a predetermined threshold), the EM field may be determined to not be stirred. However, when there is no statistical correlation between the first sample reading and the at least one second sample reading (e.g., when the correlation value related to the first sample reading and the at least one second sample reading fails to satisfy the predetermined threshold), the EM field may be determined to be stirred. To illustrate, modifying at least one parameter associated with the charged particles introduced into the EM reverberation chamber may include, at820, turning on at least one second florescent light. In another example, modifying at least one parameter associated with the charged particles introduced into the EM reverberation chamber may include, at822, changing a power level applied to the first florescent light.

FIG. 9is a flow diagram of a third particular embodiment of a method of stirring an EM field of an EM reverberation chamber. The method900may include, at902, generating an EM field in the EM reverberation chamber. The method900may also include, at904, introducing a plurality of charged particles into the EM reverberation chamber. For example, introducing a plurality of charged particles into the EM reverberation chamber may include, at906, directing an electron beam into the EM reverberation chamber.

In a particular embodiment, the method also includes, at908, stirring the EM field by varying the plurality of charged particles introduced into the EM reverberation chamber. For example, the plurality of charged particles introduced into the EM reverberation chamber may be varied, at910, by changing a focus of the electron beam. In another example, the plurality of charged particles introduced into the EM reverberation chamber may be varied, at912, by changing a direction of the electron beam. In another example, the plurality of charged particles introduced into the EM reverberation chamber may be varied, at914, by turning the electron beam on and off. For example, an electron beam gun may be cycled on and off or the electron beam may be shuttered or otherwise inhibited from entering the EM reverberation chamber to vary the introduction of the charged particles into the EM reverberation chamber. In another example, the plurality of charged particles introduced into the EM reverberation chamber may be varied, at916, by changing an intensity of the electron beam. For example, the electron beam gun may be variable to increase or decrease the power of the electron beam, thereby changing the plurality of charged particles introduced into the EM reverberation chamber.

In a particular embodiment, the method includes, at918, modifying at least one parameter associated with the charged particles introduced into the EM reverberation chamber until stirring is achieved. For example, a statistical correlation may be determined with respect to baseline readings taken before the charged particles are introduced into the EM reverberation chamber and one or more sample readings taken after the charged particles are introduced into the EM reverberation chamber. When there is a statistical correlation between the baseline readings and the one or more sample readings (e.g., when a correlation value related to the baseline readings and sample readings satisfies a predetermined threshold), the EM field may be determined to not be stirred. However, when there is no statistical correlation between the baseline readings and the one or more sample readings (e.g., when the correlation value related to the baseline readings and the sample readings fails to satisfy the predetermined threshold), the EM field may be determined to be stirred. When stirring is not achieved, the charged particles introduced into the EM reverberation chamber may be varied and another statistical correlation may be determined. Thus, the method may continue iteratively in this manner until stirring is achieved.