Patent Application
20080268790
The present invention relates to phased array antennas, and more particularly to an antenna system including a power management and control system.
Phased array antennas may be used for satellite and line-of-sight communications, and other applications related to radar/sensors, electronic warfare (EW) or the like. Radiation patterns or beams from a phased array antenna may typically be controlled or steered electronically by varying the time-delay or phasing of electrical signals to individual transmit and receive elements forming the array antenna without moving any parts. Accordingly, a power management and control system for such antenna systems needs to be efficient particularly in satellite or other space vehicle applications, terrestrial mobile vehicle applications or other applications where capacity may be limited and efficient or optimum use of power is highly desirable. Additionally, such systems are desirably reconfigurable during a mission and systems' reliability can directly impact overall system reliability and performance. For mission critical space applications in particular, electronic subsystems must be able to tolerate a certain amount of single component failures and the failures must be contained from propagating and affecting other circuits or components.
In accordance with an embodiment of the present invention, an antenna system may include a reconfigurable array antenna system including a plurality of elements each capable of radiating and/or receiving electromagnetic energy. The antenna system may also include an electronically reconfigurable power management and control system to selectively power each of the plurality of elements to generate a desired beam pattern without exceeding the system power limits.
In accordance with another embodiment of the present, a power management and control system for an array antenna system may include a host controller to control power to the array antenna system. The power management and control system may also include a beam steering controller to electronically steer the desired beam pattern generable by the array antenna system.
In accordance with another embodiment of the present, invention, a method of controlling antenna elements in an array antenna system may include selectively powering each of a plurality of elements of a reconfigurable phased array antenna system to generate a desired beam pattern within the system's total power allocation. The method may also include managing power consumption in each antenna sub-array of a plurality of antenna sub-arrays in the phased array antenna system.
Other aspects and features of the present invention, as defined solely by the claims, will become apparent to those ordinarily skilled in the art upon review of the following non-limited detailed description of the invention in conjunction with the accompanying figures.
The following detailed description of embodiments refers to the accompanying drawings, which illustrate specific embodiments of the invention. Other embodiments having different structures and operations do not depart from the scope of the present invention.
The plurality of elements 106 may include transmit elements capable of radiating electromagnetic energy or transmitting communications signals, receive elements capable of receiving electromagnetic energy or communications signals, or the elements 106 may be able to both transmit and receive electromagnetic radiation or signals. The elements 106 may include Monolithic Microwave Integrated Circuit (MMIC) devices formed or grouped in the antenna sub-arrays 108 or antenna modules.
As will be described, the antenna system 100 provides a redundant power management and distribution architecture 110 for the multiple sub-array, multi-beam phased array antenna system 104. The antenna system 100 may include a host power and control module 112, circuit or subsystem and a multi-beam antenna array module 114, circuit or subsystem.
The host power and control module 112 may include a host power converter 116 to provide step-down power conversion to reduce a line bus voltage to an intermediate voltage. The step-down power conversion may be necessary because of the physical separation between the host controller 112 and the externally installed array antenna system 104. Additionally, a power conversion ratio and low voltage and high voltage current requirements may be optimized for the multi-beam antenna array module 114 electronics by the host power converter 116.
An inline current interruptor 118, circuit breaker or similar device may connect the host power converter 116 to a voltage bus to protect the host power and control module 112 and its load or array module 114. A voltage and current display 120 may present the host or line side voltage and current for observation by a user or operator or the line side voltage and current may be transmitted to a remote location for monitoring, such as in space vehicle applications.
The host power and control module 112 may also include an antenna status display 122 to display a status of the array antenna system 104 to a user or operator. Alternatively, the antenna status also may be transmitted to a remote location as in space applications.
A delay module 124 or circuit may be connected between the host power converter 116 and a host controller 126. The host controller 126 may be connected to a beam steering controller 128 in the multi-beam antenna array system 114 by a data bus 130. The delay module 124 may provide proper timing between the host controller 126 and the beam steering controller 128 for initial establishment of bus communications over the data bus 130.
The host controller 126 may receive radio frequency (RF) signals or data for controlling the multiple beams that may be generated by the array antenna system 104. In the example illustrated in
For beam pointing, the host controller 126 may also receive location and navigation data from an inertial navigation system, global positioning system, or other positioning or navigation system via a bus 136. The location and navigation data may be conditioned and relayed by the host controller 126 to the beam steering controller 128 via the data bus 130.
The host power converter 116 may be connected to at least two antenna power converters 136 and 138 that may be in the multi-beam antenna array module 114. The two antenna power converters 136 and 138 provide redundancy and permit the power management and control system 102 to be electronically reconfigured for reliably powering the antenna sub-arrays 108 as further described herein. Each of the antenna power converters 136 and 138 may be direct current (DC) to DC power converters. The antenna power converters 136 and 138 may convert the intermediate voltage from the host power converter 116 to suitable operating voltages for the elements 106 or MMIC devices.
The multi-beam antenna array module 114 may also include a number of power sequencers 140 corresponding to the number of antenna sub-arrays 108 or antenna modules. Accordingly, the multi-beam antenna array module 114 may include a power sequencer 140 for every antenna sub-array 108. For purposes of simplicity of illustrating and describing the present invention, only two power sequencers 140 and two antenna sub-arrays 108 are shown in the exemplary embodiment of the present invention illustrated in
The power sequencers 140a and 140b may be respectively connected to the antenna power converters 136 and 138 to control a positive voltage supply (Vdd) of each antenna power converter 136 and 138 by monitoring a negative output voltage (Vss) of each converter 136 and 138. The positive voltage supply (Vdd) and the negative voltage supply or output voltage (Vss) may be respectively connected from each of the converters 136 and 138 to the respective antenna sub-arrays 108a and 108b. The positive voltage supply (Vdd) may be positive or have a positive polarity relative to a return or common ground 142 of each of the antenna power converters 136 and 138, and the negative output voltage (Vss) may be negative or negatively polarized relative to the return or common ground 142.
Each of the power sequencers 140 may include a voltage status monitoring module 144 to respectively monitor the status of each converter's negative output voltage (Vss) to control the application of the positive output voltage (Vdd) to each of the antenna sub-arrays 108. Monitoring and measuring the negative output voltage (Vss) prevents excess current drawn by the antenna elements 106 or MMIC devices which could potentially damage the devices. The voltage status monitor 144 may generate or cause to be generated a suitable reset signal to hold the positive output voltage (Vdd) off during startup of the antenna system 104 until the negative output voltage (Vss) is at a proper level to prevent any damage to the antenna elements 106 or MMIC devices.
Each power sequencer 140 may also include a power on reset module 146. The power on reset module 146 may generate or cause to be generated a reset signal to hold the positive voltage supply (Vdd) of any one of the converters 136 or 138 off, when the converter 136 or 138 is coupled to at least one of the antenna sub-arrays 108 to supply power thereto, in response to the negative output voltage (Vss) of the converter 136 or 138 dropping below an acceptable threshold voltage during normal operation of the antenna system 100.
Each of the antenna power converters 136 and 138 may also include a crowbar switch 148 or a similar device at the output terminals of the positive voltage supply (Vdd). The crowbar switch 148 may clamp the positive voltage supply (Vdd) output down before the negative voltage supply (Vss) output during a power down operation to prevent excess current drawn from the positive voltage supply (Vdd) by the antenna elements 106 or MMIC devices which could potentially damage the devices.
The multi-beam antenna array module 114 may also include a redundant power distribution switch 150 to connect power converters 136 and 138 to provide power to antenna status monitor 166 and the beam steering controller 128. An example of a redundant power distribution system that may be used for the redundant power distribution switch 150 and operation of such a switch or system is described in U.S. Pat. No. 5,654,859, entitled “Redundant Power Distribution System,” issued Aug. 5, 1997 to Fong Shi and in U.S. Pat. No. 7,190,090, entitled “Redundant Power Distribution System,” issued Mar. 13, 2007 to Fong Shi. Both of these patents are assigned to the same assignee as the present invention and are incorporated herein by reference. The redundant power distribution switch 150 provides redundant power to its loads as long as one of the power converters 136 or 138 is in operation.
In another embodiment of the present invention, not shown in the drawings, a power switch may be associated with each antenna sub-array 108 to connect a chosen one of the at least two converters 136 and 138 to selected ones of the antenna sub-arrays 104. Each power switch may respectively connect the negative output voltage (Vss) and the positive output voltage (Vdd) of the chosen one of the converters 136 and 138 to be operational to the antenna sub-arrays 108 selected to be powered during a particular mission or operation. The beam steering controller 128 may control a main power control switch that is connected to each of the power switches associated with each antenna sub-array 108 and to the negative output voltage (Vss) of each antenna power converter 136 and 138.
Accordingly, the embodiments of the present invention provide a redundant and electronically reconfigurable power management and distribution architecture and control system 102 for a multiple sub-array multi-beam phased array antenna system 104 or similar system. The power management, distribution and control system 102 is capable of isolating a failure and continuing to feed power to the antenna system 104. The system 104 is capable of self reconfiguring at the sub-array level 108, simultaneously producing a left hand and a right hand circularly polarized beam pattern 152 and 154, respectively, or either a left hand pattern 154 or right hand pattern 152 when only one circular polarization is required. For power conservation, one or more of the total available number of antenna sub-arrays 108 or beams can be turned off remotely when not needed during a particular mission or operation. The system 100 can also be easily implemented in other array architectures with more than two simultaneous beams and with multiple sub-arrays.
As previously described, the phased array antenna system 104 is a redundant design at the sub-array 108 or module level. The antenna system 104 may consist of a large number of individual sub-arrays 108 and may, therefore, be able to lose a small portion of the antenna sub-arrays 108 or modules, as long as the failed modules do not affect the power and control of the entire system 100. Power being supplied to the antenna system 104, however, may be the most critical functional block because its reliability has a direct impact on the overall system reliability. For mission critical space applications or similar application, electronic systems must be able to tolerate a single component failure and the failure must be contained from propagating and affecting other components, circuits or subsystems. For cost, weight and performance trade-offs, N numbers of redundant power switches and a minimum of two identical power supplies or converters may be necessary for an N sub-array antenna system to tolerate component failure beyond the antenna sub-array or module level. As described, the redundant power management, distribution and control system 102 of the embodiments of the present invention are capable of tolerating at least one power supply failure and being able to be reconfigured to maintain operation. Accordingly, should one of the minimum of two DC to DC antenna power converters 136 and 138 become inoperable, the other converter may continue to provide uninterruptible power for the loads.
The beam steering controller 128 may receive beam pointing commands and reconfiguration control commands for sub-array and beam switching from the host controller 126. For beam pointing commands and periodic update data, the beam steering controller 128 may calculate and load the phase shifts or time delays to individual elements 106 or MMIC devices. Beam forming may be accomplished through a predetermined number of rows and columns of dedicated clock lines 156 and data lines 158. The predetermined number of rows and columns of dedicated clock lines 156 and data lines 158 may be dependent upon the number of individual antenna elements 106 or MMIC devices that may need to be addressed or controlled to provide the desired beam pattern or radiation pattern. For example, an antenna array system similar to the antenna array system 200 illustrated in
For polarization switching, the beam steering controller 128 may simultaneously send all the control commands via two discrete control lines, beam steering line left (BSL) 160 and beam steering line right (BSR) 162, to the antenna elements 106 or MMIC devices in the antenna sub-arrays 108 for the formation of the right hand circular polarized radiation pattern 152 and the left hand pattern 154.
The beam steering controller 128 may also assert control through discrete power sequencer control lines 164 from the beam steering controller 128 to each of the power sequencers 140 to respectively command and control the positive output voltage (Vdd) from the DC to DC antenna power converters 136 and 138 or whichever converter may be active.
The multi-beam antenna array module 114 may also include an antenna status monitor module 166 to monitor an operational status of the antenna array system 104 and to report the operational status to the host controller 126. The operational status of the antenna array system 104 may be presented on the antenna status display 122. The operational status that may be displayed may include but is not necessarily limited to operational parameters, such as temperature at various locations on an antenna base plate where the antenna elements 106 or MMIC based radio frequency (RF) devices are directly attached, power conditions, power consumption of the entire antenna system 104, which sub-arrays 106 are active, or similar information that may be beneficial in monitoring the system performance and controlling the system 100.
Each antenna power converter 136 and 138 may include a positive voltage (Vdd) On/Off control 168 for the converter's main output voltage. The power sequencer 136 or 138 may control the positive output voltage (Vdd) using the On/Off control 168 by monitoring the status of the converter's negative output voltage (Vss). As previously described, the positive output voltage (Vdd) may be positive with respect to the return or common ground of the converter 136 or 138, and the negative output voltage (Vss) may be negative with respect to the same return of the same converter.
In accordance with an embodiment of the present invention, the power management and control system 102 and reconfigurable array antenna system 104 may be mounted to a vehicle 170. The vehicle 170 may be an aerospace vehicle, such as an aircraft, satellite, spacecraft or similar vehicle, a terrestrial vehicle, watercraft or other vehicle.
A DC power distribution network 214 and a RF distribution network 216 may also be embedded in each array channel 210 and 212 to distribute electrical power to each of the elements 204 and to transmit or receive RF signals to or from each of the elements 204 depending upon whether the element is transmitting or receiving signals. The power distribution network 214 may include positive output voltage (Vdd) lines 218, negative output voltage (Vss) lines 220 and return (RTN) lines 222 or common ground of the antenna power converters, such as converters 136 and 138 in
Those skilled in the art will recognize that the exemplary antenna systems 100 and 200 shown in
For an antenna aperture made up of a significant number of sub-arrays 302, as shown in
By turning on and off the antenna sub-arrays 302 as illustrated in the exemplary schemes 300a, 300b and 300c, the active portion of the antenna aperture may be rounder and thus can generate a beam profile or radiation pattern closer to that of an often desirable circular aperture. By turning on and off the antenna sub-arrays 302 as illustrated in the exemplary scheme 300d, the antenna aperture may be rounder and with a density taper, thus enabling an additional degree of freedom in terms of power conservation. Those skilled in the art will recognize that other beam configurations or patterns may be available by controlling which sub-arrays are turned on or off.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” and “includes” and/or “including” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
Although specific embodiments have been illustrated and described herein, those of ordinary skill in the art appreciate that any arrangement which is calculated to achieve the same purpose may be substituted for the specific embodiments shown and that the invention has other applications in other environments. This application is intended to cover any adaptations or variations of the present invention. The following claims are in no way intended to limit the scope of the invention to the specific embodiments described herein.
