Patent Application
20190004139
The present disclosure relates to the synthesis of electromagnetic field patterns for phased array antenna(s) with arbitrary beam forming and steering characteristics.
Communication systems installed on aircrafts, ships or even cars require electromagnetic compatibility and interference free operation. Additionally, within the aerospace industry, the Federal Aviation Administration (FAA) requires communication systems to comply with certain regulatory criteria mandating system interoperability. As a non-limiting example, aircraft systems may include primary transmitting/receiving equipment providing Air Traffic Control (ATC) communication or navigation services and secondary systems providing broadband entertainment services. As a result, FAA regulations require adequate antenna-to-antenna isolation (e.g., attenuation) between primary systems/devices providing ATC communication/navigation services (e.g., a navigation phased array antenna) and secondary communication device(s) (e.g., a second phased array antenna or a single antenna).
The isolation between the primary communication device (e.g., a primary phased array antenna) and the secondary communication device changes with the primary phased array antenna's beam forming and steering characteristics. An isolation assessment is not only based on the “worst-case” scenario, which assumes that the primary phased array antenna transmits a beam directly at the secondary communication device, but is also based on each possible beam shape and direction at the second communication device. This allows an FAA or a phased array antenna operator to setup a rule, place a mechanical/software stop, or change the design to restrict where the primary phased array antenna can be beamed to and what type of the beam shape is allowed. The “far-field pattern” is the electromagnetics term for the beam shape and direction of an antenna. The “overall far-field pattern” is designated to a phased array antenna's beam shape and direction in present disclosure. The overall far-field pattern is one parameter to determine the isolation between the primary phased array antenna and the second communication device. However, determining the overall far-field pattern is a time consuming and labor intensive process in the isolation calculation. There are many possible beam shapes and directions for a phased array antenna. It is difficult and time consuming to measure or calculate each possible overall far-field pattern (e.g., beam shape and direction).
According to one implementation of the present disclosure, a method includes determining, on an individual element-by-element basis, a normalized far-field pattern for each radiating element of a plurality of antenna elements. The plurality of antenna elements is associated with a phased array antenna. The method also includes determining an overall electromagnetic far-field pattern for the phased array antenna based on individual normalized element far-field patterns and based on beamforming parameters associated with a location of interest. The overall electromagnetic far-field pattern is usable to determine a signal strength, at the location of interest, of a signal transmitted from the phased array antenna. The method also includes determining an isolation between the phased array antenna and a secondary communication device based on the overall electromagnetic far-field pattern. The method further includes generating an output indicative of the isolation.
According to another implementation of the present disclosure, a system includes a phased array antenna and a processor coupled to the phased array antenna. The phased array antenna includes a plurality of antenna elements. The processor is configured to determine, on an individual element-by-element basis, a normalized far-field pattern for each radiating element of the plurality of antenna elements. The processor is further configured to determine an overall electromagnetic far-field pattern for the phased array antenna based on individual normalized electromagnetic far-field patterns and based on beamforming parameters associated with a location of interest. The overall electromagnetic far-field pattern is usable to determine a signal strength, at the location of interest, of a signal transmitted from the phased array antenna. The processor is also configured to determine an isolation between the phased array antenna and a secondary communication device based on the overall electromagnetic far-field pattern. The processor is further configured to generate an output indicative of the isolation.
According to another implementation of the present disclosure, a non-transitory computer-readable medium includes instructions that, when executed by a processor, cause the processor to perform operations including determining, on an individual element-by-element basis, a normalized far-field pattern for each radiating element of a plurality of antenna elements. The plurality of antenna elements is associated with a phased array antenna. The operations also include determining an overall electromagnetic far-field pattern for the phased array antenna based on individual normalized element far-field patterns and based on beamforming parameters associated with a location of interest. The overall electromagnetic far-field pattern is usable to determine a signal strength, at the location of interest, of a signal transmitted from the phased array antenna. The operations also include determining an isolation between the phased array antenna and a secondary communication device based on the overall electromagnetic far-field pattern. The operations further include generating an output indicative of the isolation.
One advantage of the above-described implementation is that electromagnetic far-field patterns of individual elements of a phased array antenna can be determined one-by-one and summed to enable determination of the collective electromagnetic far-field pattern for different beams that the phased array antenna can generate. Accordingly, the element-by-element far-field patterns can be used to determine isolation between the phased array antenna at a location of interest and a secondary communication system. Additionally, the features, functions, and advantages that have been described can be achieved independently in various implementations or may be combined in yet other implementations, further details of which are disclosed with reference to the following description and drawings.
Particular embodiments of the present disclosure are described below with reference to the drawings. In the description, common features are designated by common reference numbers throughout the drawings.
The figures and the following description illustrate specific exemplary embodiments. It will be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described or shown herein, embody the principles described herein and are included within the scope of the claims that follow this description. Furthermore, any examples described herein are intended to aid in understanding the principles of the disclosure and are to be construed as being without limitation. As a result, this disclosure is not limited to the specific embodiments or examples described below, but by the claims and their equivalents.
The techniques described herein enable a processor (e.g., a simulator) to generate an overall electromagnetic far-field pattern (e.g., a far-field pattern for a phased array antenna) based on individual normalized element far-field patterns for each radiating element of a phased array antenna. For example, a phased array antenna simulator activates (e.g., excites) each antenna element of the phased array antenna individually by applying a normalized power and a normalized phase to each antenna element sequentially. While a particular antenna element is activated, one or more sensors measure, or calculate, a far-field pattern associated with the particular antenna element. After far-field patterns are measured or calculated for each antenna element of the phased array antenna, the overall electromagnetic far-field pattern of the phased array antenna device can be estimated by beamforming and summing the individual far-field patterns of the antenna elements. For example, the overall electromagnetic far-field pattern is based on each far-field pattern associated with the different antenna elements and beamforming parameters associated with the location of interest. The beamforming parameters include a power level and a phase for each antenna element to beam the phased array antenna to a location of interest. Additional details clarifying how the overall electromagnetic far-field pattern is determined are described below.
The overall electromagnetic far-field pattern with the given beamforming parameters can be used to determine (e.g., calculate) attenuation at a location of interest, an equivalent source current can be obtained through electromagnetic methods, such as Uniform Theory of Diffraction (UTD), antenna coupling between the phased array antenna device and another antenna device, etc. For example, antenna coupling can be used to determine whether the phased array antenna device with the given beamforming parameters is in compliance with standards and criteria set forth by the Federal Aviation Administration (FAA). To illustrate, the FAA requires adequate isolation and attenuation between communication devices (e.g., a phased array antenna device) providing broadband communication services on an aircraft and other antennas on the aircraft.
In
The phased array antenna controller 112 is coupled to the phased array antenna 188. The phased array antenna 188 includes a plurality of element controllers and a plurality of antenna elements. For example, the phased array antenna 188 includes an element controller 195, an element controller 196, an element controller 197, and an element controller 198. The element controller 195 includes a phase shifter (PS) 121 coupled to a power amplifier (PA) 125, the element controller 196 includes a phase shifter 122 coupled to a power amplifier 126, the element controller 197 includes a phase shifter 123 coupled to a power amplifier 127, and the element controller 198 includes a phase shifter 124 coupled to a power amplifier 128. Each phase shifter 121-124 is coupled to receive one or more signals (e.g., phase input signals) from the phase controller 116, and each power amplifier 125-128 is coupled to receive one or more signals (e.g., power level input signals) from the power controller 118. Although four element controllers 195-198 are illustrated in
The system 100 is configured to determine a far-field pattern 151-154 for each antenna element 131-134, respectively, on an element-by-element basis. For example, the system 100 activates (e.g., excites) each antenna element 131-134 one-by-one to determine the far-field pattern 151-154 for each antenna element 131-134, respectively. After determining each far-field pattern 151-154, an overall electromagnetic far-field pattern 180 of the phased array antenna 188 can be determined based on the far-field patterns 151-154 and beamforming parameters associated with a location of interest, as described below.
To illustrate, during operation, the element selector 104 initiates determination of the far-field pattern 151 for the antenna element 131. The selection circuitry 120 generates the element selection signal 140 indicating that the antenna element 131 is selected for activation and the other antenna elements 132-134 are selected for deactivation. The element selection signal 140 is provided to the phased array antenna controller 112. Based on the element selection signal 140, the phase controller 116 generates a normalized phase input 142 that adjusts a phase of the phase shifter 121 (coupled to the antenna element 131) to a normalized phase. As used herein, the “normalized phase” corresponds to a phase used by each phase shifter 121-124 to determine the far-field patterns 151-154. The phase controller 116 provides the normalized phase input 142 to the phase shifter 121. Additionally, upon receiving the element selection signal 140, the power controller 118 generates a normalized power level input 141 that adjusts a power level of the power amplifier 125 to a normalized power level. As used herein, the “normalized power level” corresponds to a power level provided to the power amplifiers 125-128 to determine the far-field patterns 151-154.
In response to receiving the normalized phase input 142 and the normalized power level input 141, the element controller 195 excites the antenna element 131 to generate the far-field pattern 151. The far-field pattern 151 is indicative of a radiation pattern, at a particular distance from the antenna element 131, of an electromagnetic field surrounding the antenna element 131.
Referring now to both
Additionally, during operation, the element selector 104 initiates determination of the far-field pattern 152 for the antenna element 132. The selection circuitry 120 generates the element selection signal 140 indicating that the antenna element 132 is selected for activation and the other antenna elements 131, 133, 134 are selected for deactivation. The element selection signal 140 is provided to the phased array antenna controller 112. Based on the element selection signal 140, the phase controller 116 generates the normalized phase input 142 that adjusts a phase of the phase shifter 122 (coupled to the antenna element 132) to the normalized phase. The phase controller 116 provides the normalized phase input 142 to the phase shifter 122. Additionally, upon receiving the element selection signal 140, the power controller 118 generates the normalized power level input 141 that adjusts a power level of the power amplifier 126 to the normalized power level.
In response to receiving the normalized phase input 142 and the normalized power level input 141, the element controller 196 excites the antenna element 132 to generate the far-field pattern 152. Referring to
The element selector 104 also initiates determination of the far-field pattern 153 for the antenna element 133. The selection circuitry 120 generates the element selection signal 140 indicating that the antenna element 133 is selected for activation and the other antenna elements 131, 132, 134 are selected for deactivation. The element selection signal 140 is provided to the phased array antenna controller 112. Based on the element selection signal 140, the phase controller 116 generates the normalized phase input 142 that adjusts a phase of the phase shifter 123 (coupled to the antenna element 133) to the normalized phase. The phase controller 116 provides the normalized phase input 142 to the phase shifter 123. Additionally, upon receiving the element selection signal 140, the power controller 118 generates the normalized power level input 141 that adjusts a power level of the power amplifier 127 to the normalized power level.
In response to receiving the normalized phase input 142 and the normalized power level input 141, the element controller 197 excites the antenna element 133 to generate the far-field pattern 153. Referring to
The element selector 104 also initiates determination of the far-field pattern 154 for the antenna element 134. The selection circuitry 120 generates the element selection signal 140 indicating that the antenna element 134 is selected for activation and the other antenna elements 131, 132, 133 are selected for deactivation. The element selection signal 140 is provided to the phased array antenna controller 112. Upon receiving the element selection signal 140, the phase controller 116 generates the normalized phase input 142 that adjusts a phase of the phase shifter 124 (coupled to the antenna element 134) to the normalized phase. The phase controller 116 provides the normalized phase input 142 to the phase shifter 124. Additionally, upon receiving the element selection signal 140, the power controller 118 generates the normalized power level input 141 that adjusts a power level of the power amplifier 128 to the normalized power level.
In response to receiving the normalized phase input 142 and the normalized power level input 141, the element controller 198 excites the antenna element 134 to generate the far-field pattern 154. Referring to
After the far-field pattern data 171-174 is determined for each antenna element 131-134, respectively, the overall electromagnetic far-field pattern determination circuitry 110 can determine the overall electromagnetic far-field pattern 180 for the phased array antenna 188. The overall electromagnetic far-field pattern for the phased array antenna 188 is determined based on each far-field pattern 151-154 and based on beamforming parameters 191, 192, 193, 194 associated with a location of interest, as depicted in
Referring back to
The overall electromagnetic far-field pattern 180 is expressed as:
{right arrow over (E)}(θ,Ø,f)=Σi=1NAi(f){right arrow over (e)}i(θ,Ø,f)exp(−jβi(f)), (Equation 1)
where {right arrow over (E)} corresponds to the overall electromagnetic far-field pattern 180, where Ai corresponds to the power level for a particular antenna element 131-134, where {right arrow over (e)}i corresponds to the far-field pattern 151-154 for the particular antenna element 131-134, where βi corresponds to the phase input for the particular antenna element 131-134, where N is the number of antenna elements, where f is the frequency, and where θ and Ø are spherical coordinates for the direction of the field. According to the described implementation, N is equal to four. However, it should be understood that N may be any integer value greater than one. Thus, determining the overall electromagnetic far-field pattern 180 includes adding a first electromagnetic far-field pattern (e.g., A1(f){right arrow over (e)}1(θ, Ø, f)exp(−jβ1(f))), a second electromagnetic far-field pattern ((e.g., A2(f){right arrow over (e)}2(θ, Ø, f)exp(−jβ2(f))), a third electromagnetic far-field pattern (e.g., A3{right arrow over ((f)e)}3(θ, Ø, f)exp(−jβ3(f))), and a fourth electromagnetic far-field pattern (e.g., A4{right arrow over ((f)e)}4(θ, Ø, f)exp(−jβ4(f))).
The first electromagnetic far-field pattern is based on a product of the power level (A1) associated with the beamforming parameters 191 and the far-field pattern ({right arrow over (e)}1) 151 exponentially adjusted by the phase input (exp(−jβ1)) associated with beamforming parameters 191. The second electromagnetic far-field pattern is based on a product of the power level (A2) associated with the beamforming parameters 192 and the far-field pattern ({right arrow over (e)}2) 152 exponentially adjusted by the phase input (exp(−jβ2)) associated with beamforming parameters 192. The third electromagnetic far-field pattern is based on a product of the power level (A3) associated with the beamforming parameters 193 and the far-field pattern ({right arrow over (e)}3) 153 exponentially adjusted by the phase input (exp(−jβ3)) associated with beamforming parameters 193, and the fourth electromagnetic far-field pattern is based on a product of the power level (A4) associated with the beamforming parameters 194 and the far-field pattern ({right arrow over (e)}4) 154 exponentially adjusted by the phase input (exp (−jβ4)) associated with beamforming parameters 194.
After determining the overall electromagnetic far-field pattern 180, the processor 111 determines, based on the overall electromagnetic far-field pattern 180, an isolation (e.g., an antenna isolation 182) between the phased array antenna 188 and the phased array antenna 304 at the location of interest 302. For example, the processor 111 coverts he overall electromagnetic far-field pattern to an equivalent source current 181 using an electromagnetic method, such as Uniform Theory of Diffraction (UTD). The processor 111 also determines the antenna isolation 182 based on the equivalent source current 181. The processor also generates an output indicative of the isolation.
The techniques described with respect to
Referring to
At 402, a single antenna element in a phased antenna array is activated (e.g., excited) with a normalized phase and a normalized power level. For example, referring to
At 404, a far-field pattern of the single antemia element is determined (e.g., measured). For example, referring to
At 406, the far-field pattern is stored in memory. For example, referring to
At 408, a determination of whether the single antenna element is the last antenna element in the phase antenna array is made. If the single antenna element is not the last antenna element, another antenna element is activated, at 402. For example, the normalized phase and the normalized power level are provided to the element controller 196 to activate the antenna element 132. The far-field pattern 152 for the antenna element 132 is determined and stored in the memory 108, etc.
If the single antenna element is the last antenna element, the phase antenna array is beamed to a location of interest to determine an overall electromagnetic far-field pattern, at 410. For example, referring to
At 412, the overall electromagnetic far-field pattern is converted to an equivalent source current through an electromagnetic algorithm, such as Uniform Theory of Diffraction (UTD). For example, referring to
At 414, an antenna coupling between the phased antenna array and a second communication device is determined using, but not limited to, Geometrical Theory of Diffraction (GTD)/Uniform Theory of Diffraction (UTD) techniques. For example, referring to
At 416, if there are other locations of interest (or other communication devices), the process diagram 400 beams the phased array antenna 188 to the other locations of interest to determine corresponding antenna couplings. Otherwise, the process diagram 400 ends.
Referring to
The method 500 includes determining, on an individual element-by-element basis, a normalized far-field pattern for each radiating element of a plurality of antenna elements, at 502. The plurality of antenna elements is associated with a phased array antenna. For example, referring to
According to one implementation, determining the far-field pattern for each antenna element includes activating a first antenna element of the plurality of antenna elements at a first time to determine a first far-field pattern for the first antenna element. Activating the first antenna element to determine the first far-field pattern includes applying a normalized power level to a first power amplifier that is coupled to the first antenna element and applying a normalized phase input to a first phase shifter that is coupled to the first antenna element. For example, referring to
Determining the far-field pattern for each antenna element also includes activating a second antenna element of the plurality of antenna elements at a second time to determine a second far-field pattern for the second antenna element. Activating the second antenna element to determine the second far-field pattern includes applying the normalized power level to a second power amplifier that is coupled to the second antenna element and applying the normalized phase input to a second phase shifter that is coupled to the second antenna element. For example, referring to
The method 500 also includes determining an overall electromagnetic far-field pattern for the phased array antenna based on individual normalized far-field patterns and based on beamforming parameters associated with a location of interest, at 504. For example, the overall electromagnetic far-field pattern determination circuitry 110 determines the overall electromagnetic far-field pattern 180 based on the far-field patterns 151-154 and the beamforming parameters 191-194. The overall electromagnetic far-field pattern 180 is expressed as:
{right arrow over (E)}(θ,Ø,f)=Σi=1NAi(f){right arrow over (e)}i(θ,Ø,f)exp(−jβi(f)), (Equation 1)
where {right arrow over (E)} corresponds to the overall electromagnetic far-field pattern 180, where Ai corresponds to the power level for a particular antenna element 131-134, where {right arrow over (e)}i corresponds to the far-field pattern 151-154 for the particular antenna element 131-134, where βi corresponds to the phase input for the particular antenna element 131-134, where N is the number of antenna elements, where f is the frequency, and where θ and Ø are spherical coordinates for the direction of the field. Thus, determining the overall electromagnetic far-field pattern 180 includes adding a first electromagnetic far-field pattern (e.g., A1(f){right arrow over (e)}1(θ, Ø, f)exp(−jβ1(f))), a second electromagnetic far-field pattern ((e.g., A2{right arrow over ((f)e)}2(θ, Ø, f)exp(−jβ2(f))), a third electromagnetic far-field pattern (e.g., A3{right arrow over ((f)e)}3(θ, Ø, f)exp(−jβ3(f))), and a fourth electromagnetic far-field pattern (e.g., A4(f){right arrow over (e)}4(θ, Ø, f)exp(−jβ4(f))).
The first electromagnetic field pattern is based on a product of the power level (A2) associated with the beamforming parameters 191 and the far-field pattern ({right arrow over (e)}1) 151 exponentially adjusted by the phase input (exp(−jβ1)) associated with beamforming parameters 191. The second electromagnetic far-field pattern is based on a product of the power level (A2) associated with the beamforming parameters 192 and the far-field pattern ({right arrow over (e)}2) 152 exponentially adjusted by the phase input (exp(−jβ2)) associated with beamforming parameters 192. The third electromagnetic far-field pattern is based on a product of the power level (A3) associated with the beamforming parameters 193 and the far-field pattern ({right arrow over (e)}3) 153 exponentially adjusted by the phase input (exp(−jβ3)) associated with beamforming parameters 193, and the fourth electromagnetic far-field pattern is based on a product of the power level (A4) associated with the beamforming parameters 194 and the far-field pattern ({right arrow over (e)}4) 154 exponentially adjusted by the phase input (exp(−jβ4)) associated with beamforming parameters 194.
The method 500 also includes determining an isolation between the phased array antenna and a secondary communication device based on the overall electromagnetic far-field pattern, at 506. For example, referring to
The method 500 of
Referring to
The memory 108 is a non-transitory computer-readable medium that includes instructions 604 that are executable by the processor 602. For example, the memory 108 stores instructions 604 that are executable by the processor 602 to perform the operations described with respect to the process diagram 400 of
To illustrate, the instructions 604 are executable to cause the processor 602 to determine, on an element-by-element basis, a far-field pattern for each antenna element 131-134 of the plurality of antenna elements. The instructions 604 are also executable to cause the processor 602 to determine the overall electromagnetic far-field pattern 180 based on the beamforming parameters 191-194 associated with the location of interest 302. The instructions 604 are further executable to cause the processor 602 to determine the antenna isolation 182 between the phased array antenna 188 and another communication device based on the overall electromagnetic far-field pattern 180. The instructions 604 are further executable to cause the processor 602 to generate an output indicative of the antenna isolation 182.
Referring to
The instructions 782, when executed by the processor 602, may cause the processor 602 to perform any of the functions described above. For example, the instructions 782, when executed by the processor 602, may cause the processor 602 to determine, on an element-by-element basis, a far-field pattern for each antenna element 131-134 of the plurality of antenna elements. The instructions 782 are also executable to cause the processor 602 to determine the overall electromagnetic far-field pattern 180 based on the beamforming parameters 191-194 associated with a location of interest, such as the location of interest 302 in
The illustrations of the examples described herein are intended to provide a general understanding of the structure of the various implementations. The illustrations are not intended to serve as a complete description of all of the elements and features of apparatus and systems that utilize the structures or methods described herein. Many other implementations may be apparent to those of skill in the art upon reviewing the disclosure. Other implementations may be utilized and derived from the disclosure, such that structural and logical substitutions and changes may be made without departing from the scope of the disclosure. For example, method operations may be performed in a different order than shown in the figures or one or more method operations may be omitted. Accordingly, the disclosure and the figures are to be regarded as illustrative rather than restrictive.
Moreover, although specific examples have been illustrated and described herein, it should be appreciated that any subsequent arrangement designed to achieve the same or similar results may be substituted for the specific implementations shown. This disclosure is intended to cover any and all subsequent adaptations or variations of various implementations. Combinations of the above implementations, and other implementations not specifically described herein, will be apparent to those of skill in the art upon reviewing the description.
The Abstract of the Disclosure is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, various features may be grouped together or described in a single implementation for the purpose of streamlining the disclosure. Examples described above illustrate but do not limit the disclosure. It should also be understood that numerous modifications and variations are possible in accordance with the principles of the present disclosure. As the following claims reflect, the claimed subject matter may be directed to less than all of the features of any of the disclosed examples. Accordingly, the scope of the disclosure is defined by the following claims and their equivalents.
