Patent Application
20160049727
In certain implementations, such as space radio frequency and payloads, systems use devices in a high power radio frequency (RF) network that combine inputs and direct the inputs to a particular antenna in a group of antennas. For example, the inputs may be provided by two travelling wave tube amplifiers (TWTAs). In certain applications, when the inputs from multiple TWTAs are combined, the combined power may be too great for a system comprised of ferrite switching circulators. Other implementations use variations of a Butler matrix in combination with a series of phase shifters. The Butler matrices reduce the power that passes through the phase shifters and, in general, are better suited for high power applications. However, when there are less inputs than outputs, the combination of Butler matrices connected to each side of the phase shifters leads to an inefficient combination of couplers.
Systems and methods for high power microwave combining and switching are provided. In at least one implementation a system includes a plurality of inputs, wherein there are M inputs in the plurality of inputs and a plurality of phase shifters, wherein there are N phase shifters in the plurality of phase shifters and N is a multiple of two times M, wherein a signal received through the plurality of inputs is divided and coupled to N/M phase shifters. The system further includes an N:N Butler matrix coupled between outputs of the N phase shifters in the plurality of phase shifters and a plurality of outputs.
Understanding that the drawings depict only exemplary embodiments and are not therefore to be considered limiting in scope, the exemplary embodiments will be described with additional specificity and detail through the use of the accompanying drawings, in which:
In accordance with common practice, the various described features are not drawn to scale but are drawn to emphasize specific features relevant to the exemplary embodiments.
In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific illustrative embodiments. However, it is to be understood that other embodiments may be utilized and that logical, mechanical, and electrical changes may be made. Furthermore, the method presented in the drawing figures and the specification is not to be construed as limiting the order in which the individual steps may be performed. The following detailed description is, therefore, not to be taken in a limiting sense.
Embodiments described in this application are drawn to systems and methods for high power microwave combining and switching that more efficiently uses couplers when providing received energy to a series of phase shifters. To increase the efficiency of the couplers when there are at least twice as many outputs as inputs, signals received from an input are distributed to a subset of the phase shifters, where there are the same number of phase shifters as outputs. The outputs of the phase shifters are each connected to an input of a Butler matrix. Then, depending on the phase of the signals and the configuration of the phase shifters, signals that are received through the inputs of the system can be directed and combined so that all the power received through the inputs is directed to a particular output.
In embodiments described herein, when routing the M inputs to the N outputs, the system 100 may be constrained by certain conditions in order to implement the system 100. In one implementation, the number of inputs and outputs of the system may be constrained such that the number of inputs M is greater than 1 and less than or equal to the number of outputs N divided by 2 (1<M≦N/2). Further, the number of inputs M may be constrained to being an even number. Also, the number of outputs N may be constrained to the nearest power of 2 that is greater than the actual number of outputs used from the system 100. For example, if the system 100 connects to six antennas, the system 100 will provide eight outputs, where six of the eight outputs are connected to the six antennas and the other two outputs are terminated with a load.
In certain embodiments, to combine the different signals received through the M inputs, the system 100 first passes the M inputs through different sets of power dividers 104. As described herein, the system 100 includes M different 1:N/M power dividers 104. In one exemplary implementation, in a system with sixteen outputs and having 4 inputs, each input is connected to a 1:(16/4) or 1:4 power divider. In a similar manner, a system with 8 outputs and having 4 inputs, would have 1:2 power dividers. Where the system has 1:N/M power dividers, each power divider receives one input and divides the power between N/M different outputs.
In at least one embodiment, the M power dividers are coupled to N different phase shifters 106. The phrase “phase shifter”, as used herein, refers to a device that is used to change the transmission phase angle of a signal in a network. As used in the system 100, the phase shifters 106 may be controllable to either a reference phase state of 0° or a phase state 180° different from the reference 0° state. Therefore, when RF energy flows through a phase shifter, it undergoes a change in the phase of a signal by either 0° or 180° degrees of relative phase shift. Each phase shifter 106 may be controllable by another device that determines its shift and provides a signal to the desired phase shifter in the phase shifters 106. Further, each phase shifter 106 receives a portion of the power received by the M power dividers. For example, an input may supply power through a power divider to four different phase shifters 106. When the power divider provides power to four different phase shifters 106, the power divider divides the power of the received signal from an associated input such that each connected phase shifter 106 receives the signal at substantially the same power. For example, when there are four phase shifters connected to a single power divider, each phase shifter 106 may receive the signal at a quarter of the original power.
Further, each phase shifter in the N phase shifters 106 functions as one of the inputs to an N:N Butler Matrix 108. As used herein, the Butler matrix 108 refers to a matrix in RF networks and may be used for beam-forming and other Transmission technologies. It generally is characterized by having N inputs and N outputs, where N is a multiple of 2. Further, the Butler matrix 108 includes multiple couplers, such as 3 dB couplers that couple the inputs to one or more of the outputs depending on the configuration of the phase shifters 106. In particular, the phase shifters 106 may be configured to control which output or outputs receive the signals from the Butler matrix 108.
In at least one implementation, the outputs of the Butler matrix 108 are coupled to a series of antenna elements. In one example, there are N antenna elements coupled to the N outputs 110 of the Butler matrix 108. Alternatively, there may be less than N antenna elements coupled to the N outputs 110 of the Butler matrix 108. When there are less than N antenna elements coupled to the N outputs 110 of the Butler matrix 108, outputs 110 that are not coupled to an antenna element may be coupled to a matched load to absorb signals that are transmitted to the output. Further any unnecessary couplers within the Butler matrix 108 may be removed when 1 or more of the outputs are terminated by a matched load.
As described above, the use of M 1:(N/M) power dividers between the inputs and the phase shifters allows the combining/switching system 100 to be fabricated using less couplers and fewer crossing waveguides. By using less couplers, the system 100 is able to consume less space while still being able to handle high power signals, such as signals provided by multiple TWTAs.
In certain implementations, the system 200 receives two inputs 202 from separate TWTAs 218. Each output of each TWTA 218 is connected to a ferrite circulator 220, which circulates the signal towards the power dividers 204. Each input 202 is connected to a power divider 204 that divides the signal into two different branches. Each branch from the power divider 204 connects to N/M different phase shifters. As N=4 and M=2, the power dividers 204 each divide the power from a single input 202 and provide the divided power to two separate phase shifters 206. As illustrated, to divide the power from the input into two different phase shifters, each power divider 204 comprises a single 3 dB coupler. As illustrated, the 3 dB couplers each have one connection terminated with a load 224. In a similar manner, the circulators 220 also have a connection terminated with a load 222. The loads 222 and 224 may be matched loads that absorb signals to prevent the reflection of signals within the combining/switching system 200.
Further, the phase shifters 206 may be configurable to control the phase shift to be either 0 or 180 degrees. As understood by one having skill in the art, by controlling the shifts performed by the phase shifters 206, the system 200 is able to control the manner in which the different signals combine within the Butler matrix 208. By controlling how the signals combine in the Butler matrix 208, the signals can be routed to a particular output 210. Wherein the different outputs may each be connected to antennas 226. Thus, the phase shifters 206 and Butler matrix 208, after receiving the different signals from the power dividers 204, are able to combine and/or switch signals received from the inputs 202 towards a particular output 210. By routing the different signals, the system 200 may be used for beam-forming and other system implementations.
In certain implementations, the system 300 receives two inputs 302 from separate TWTAs 318. Each output of each TWTA 318 is connected to a ferrite circulator 320, which circulates the signal towards the power dividers 304. Each input 302 is connected to a power divider 304 that divides the signal into four different branches. Each input to the power dividers 304 connects to N/M different phase shifters. As N=8 and M=2, the power dividers 304 each divide the power from a single input 302 into four signals and provide the signals having the divided power to four separate phase shifters 306. As illustrated, to divide the power from an input into four different phase shifters, each power divider 304 comprises three 3 dB couplers. To divide a single input into four outputs, a circulator 320 provides an input into a single 3 dB coupler, which divides the input into two different outputs for the 3 dB coupler. Each of the outputs is then provided to a separate 3 dB coupler which further divides the signal from two inputs to four outputs, where each of the four outputs is provided to a separate phase shifter in the phase shifters 306. As shown there are two sets of power dividers 304, where each set of power dividers 304 is associated with a different input 302. As further illustrated, each of the 3 dB couplers in power dividers 304 have one connection terminated with a load 324. In a similar manner, the circulators 320 also have a connection terminated with a load 322. The loads 322 and 324 may be matched loads that absorb signals to prevent the reflection of signals within the combining/switching system 300. As shown in
In a further implementation, the phase shifters 306 may be configurable to control the phase shift to be either 0 or 180 degrees. As understood by one having skill in the art, by controlling the shifts performed by the phase shifters 306, the system 300 is able to control the manner in which the different signals combine within the 8×8 Butler matrix 308. By controlling how the signals combine in the Butler matrix 308, the signals can be routed to a particular output 310. Wherein the different outputs 310 may each be connected to antennas 326. Thus, the phase shifters 306 and Butler matrix 308, after receiving the different signals from the power dividers 304, are able to combine and/or switch signals received from the inputs 302 towards a particular output 310 in a 2 to 8 combining and switching matrix.
In certain implementations, the system 400 receives four inputs 402 from four different TWTAs 418. Each output of each TWTA 418 is connected to a ferrite circulator 420, which circulates the signal towards the power dividers 404. Each input 402 is connected to a power divider 404 that divides the signal into two different branches in a similar manner as described with relation to power dividers 204 in
In a further implementation, the phase shifters 406 may be configurable to control the phase shift to be either 0 or 180 degrees. As understood by one having skill in the art, by controlling the shifts performed by the phase shifters 406, the system 400 is able to control the manner in which the different signals combine within the 8×8 Butler matrix 408 in a similar manner as described above in relation to the 8×8 Butler matrix 308 in
In certain implementations, the system 500 receives two inputs 502 from two separate TWTAs 518. Each output of each TWTA 518 is connected to a ferrite circulator, which circulates the signal towards the power dividers 504. Each input 502 is connected to a power divider 504 that divides the signal into two different branches in a similar manner as described with relation to power dividers 204 in
In a further implementation, the phase shifters 506 may be configurable to control the phase shift to be either 0 or 180 degrees. As understood by one having skill in the art, by controlling the shifts performed by the phase shifters 506, the system 500 is able to control the manner in which the different signals combine within the 4×4 Butler matrix 508 in a similar manner as described above in relation to the 4×4 Butler matrix 208 in
In at least one embodiment, method 600 proceeds at 606 where signals output from the plurality of phase shifters are routed through a Butler matrix to a plurality of outputs by controlling the phase shifts of the plurality of phase shifters. In at least one implementation, the outputs are coupled to antennas in an antenna array and the signals are routed through the Butler matrix to a particular antenna in the antenna array. By combining the signals as described above, the combining and routing of the signals may be performed with fewer components and fewer crossing waveguides. Thus, systems made accordingly may be made less expensive, lower in mass, and smaller in size.
Example 1 includes a system, the system comprising: a plurality of inputs, wherein there are M inputs in the plurality of inputs; a plurality of phase shifters, wherein there are N phase shifters in the plurality of phase shifters and N is a multiple of two times M, wherein a signal received through the plurality of inputs is divided and coupled to N/M phase shifters; and an N:N Butler matrix coupled between outputs of the N phase shifters in the plurality of phase shifters and a plurality of outputs.
Example 2 includes the system of Example 1, wherein the plurality of outputs comprises N outputs.
Example 3 includes the system of any of Examples 1-2, wherein the plurality of outputs comprises less than N outputs and an output of the N:N Butler matrix that is not coupled to an output in the plurality of outputs is terminated with a matched load.
Example 4 includes the system of Example 3, wherein the N:N Butler matrix is altered to remove 3 dB couplers that route signals to pairs of matched loads.
Example 5 includes the system of any of Examples 1-4, wherein a signal received through the plurality of inputs is divided by one or more 3 dB couplers, wherein one input of the 3 dB coupler is coupled to a matched load and another input is coupled to one of an input in the plurality of inputs or an output from another 3 dB coupler.
Example 6 includes the system of any of Examples 1-5, wherein the plurality of inputs receive signals from a plurality of travelling wave tube amplifiers.
Example 7 includes the system of any of Examples 1-6, wherein the plurality of outputs connect to a plurality of antennas in an antenna array.
Example 8 includes the system of Example 7, wherein the plurality of phase shifters are controllable to route the propagation of signals through the N:N Butler matrix to specific antennas in the plurality of antennas.
Example 9 includes a method for combining signals, the method comprising: receiving a plurality of signals through a plurality of inputs; distributing each signal in the plurality of signals to a set of phase shifters in a plurality of phase shifters, wherein there are a multiple of two times as many phase shifters in the plurality of phase shifters as there are inputs in the plurality of inputs and the number of phase shifters in the set of phase shifters is equal to the number of phase shifters in the plurality of phase shifters divided by the number of inputs in the plurality of inputs; and routing signals output from the plurality of phase shifters through a Butler matrix to a plurality of outputs by controlling the phase shifts of the plurality of phase shifters.
Example 10 includes the method of Example 9, wherein the number of outputs in the plurality of outputs is less than the number of phase shifters in the plurality of phase shifters and an output of the Butler matrix that is not coupled to an output in the plurality of outputs is terminated with a matched load.
Example 11 includes the method of Example 10, wherein the Butler matrix is altered to remove 3 dB couplers that route signals to pairs of matched loads.
Example 12 includes the method of any of Examples 9-11, wherein distributing each signal in the plurality of signals comprise routing the signal through one or more 3 dB couplers, wherein one input of the 3 dB coupler is coupled to a matched load and another input is coupled to one of an input in the plurality of inputs or an output from another 3 dB coupler.
Example 13 includes the method of any of Examples 9-12, wherein the plurality of signals are received from a plurality of travelling wave tube amplifiers.
Example 14 includes the method of any of Examples 9-13, further comprising providing the signals to a plurality of antennas in an antenna array, wherein the plurality of outputs connect to the plurality of antennas.
Example 15 includes the method of Example 14, wherein the signals output from the plurality of phase shifters are routed to specific antennas in the plurality of antennas.
Example 16 includes a combining and switching system, the system comprising: a plurality of inputs, wherein the plurality of inputs receive radio frequency signals; a plurality of power dividers coupled to the plurality of inputs; a plurality of phase shifters, wherein there are a multiple of two times as many phase shifters in the plurality of phase shifters as there are inputs in the plurality of inputs, wherein each power divider in the plurality of power dividers distributes a signal received through an input in the plurality of inputs to a set of phase shifters, wherein the number of phase shifters in the set of phase shifters is equal to the number of phase shifters in the plurality of phase shifters divided by the number of inputs in the plurality of inputs; a Butler matrix coupled to outputs for the plurality of phase shifters, wherein the Butler matrix routes signals received from the phase shifters to a plurality of outputs.
Example 17 includes the system of Example 16, wherein the number of outputs in the plurality of outputs is less than the number of phase shifters in the plurality of phase shifters and an output of the Butler matrix that is not coupled to an output in the plurality of outputs is terminated with a matched load.
Example 18 includes the system of any of Examples 16-17, wherein a signal received through the plurality of inputs is divided by one or more 3 dB couplers, wherein one input of the 3 dB coupler is coupled to a matched load and another input is coupled to one of an input in the plurality of inputs or an output from another 3 dB coupler.
Example 19 includes the system of any of Examples 16-18, wherein the plurality of inputs receive signals from a plurality of travelling wave tube amplifiers.
Example 20 includes the system of any of Examples 1-19, wherein the plurality of outputs connect to a plurality of antennas in an antenna array, wherein the plurality of phase shifters are controllable to route the propagation of signals through the Butler matrix to specific antennas in the plurality of antennas.
Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any arrangement, which is calculated to achieve the same purpose, may be substituted for the specific embodiments shown. Therefore, it is manifestly intended that this invention be limited only by the claims and the equivalents thereof.
