The present invention relates generally to phased array antenna design and more specifically to modular and stackable phased array antennas.
An antenna array is a group of multiple connected antennas coupled to a common source or load to act as a single antenna and produce a directive radiation pattern. Usually, the spatial relationship of the individual antennas also contributes to the directivity of the antenna array.
An Electronically Scanned Array (ESA) is a type of phased array antenna, in which transceivers include a large number of solid-state transmit/receive modules. In ESAs, an electromagnetic beam is emitted by broadcasting radio frequency energy that interferes constructively at certain angles in front of the antenna. An active electronically scanned array (AESA) is a type of phased array antenna whose transmitter and receiver (transceiver) functions are composed of numerous small solid-state transmit/receive modules (TRMs) or components. AESA antennas aim their beam by emitting separate radio waves from each module that are phased shifted or time delayed so that waves interfere constructively at certain angles in front of the antenna.
Typically, the basic building block of a conventional AESA is the Transmit/Receive module or TR module, which can be packaged to form an AESA antenna element, and may include a radiator, receiver Low Noise Amplifier (LNA), transmit Power Amplifier (PA), and digitally controlled phase or delay and gain components. Several of these TR modules are placed on antenna panels in a grid format for transmitting and receiving radar signals. Digital control of the transmit/receive gain and phase allows an AESA antenna to steer or point the resultant antenna beam without physically moving the antenna panel. Typical modern day low cost AESA antenna panels employ printed circuit radiators connected to surface mount Monolithic Microwave Integrated Circuit (MMIC) devices that contain the LNA, PA and phase/gain control circuitry, all on a single printed circuit board (PCB).
Typically, antenna arrays are designed in a platform or housing that must be sized for frequency and gain by changing the structural elements of the platform. For example, larger antenna elements are needed for lower frequencies and smaller antenna elements are required for higher frequencies, while increasing the number of antenna elements is necessary to increase the antenna gain. However, the antenna platform is generally a fixed structure and typically cannot be modified to accommodate such changes or improvements in the design and therefore is not capable of easy adjustment of the frequency range and gain since they are generally fixed in the structure. Additionally, since these antenna arrays are specifically built for the specified frequency, gain, polarization, beam width, and other requirements, the lead time to make any design changes or performance improvements is very long.
Moreover, these architectures feature structure, support electronics and thermal management subsystems that extend beyond the active antenna area and to the edges 202 of the array and thus are not amenable to adding additional array building blocks without extensive redesign.
Since these conventional antenna architectures have structure and supporting electronics that extend beyond the active region of the antenna, this makes it impractical to stack one antenna on top of, or next to, another because it would create a disruption in the radiating element lattice pattern that would negatively impact radar performance. In addition, in many legacy systems the power and beamforming overlap from one building block to another, making it impossible to stack antennas. Consequently, the structure, interconnects, and thermal management infrastructure need to be extensively redesigned to change the size of the antenna.
In some embodiments, the disclosed invention is a modular phased array antenna that includes a plurality of modular antenna array blocks assembled together as a single antenna array and an array face having an array plate and a radiator and radome assembly for each modular block interlocked and aligned to create a single monolithic array face. Each modular antenna array block includes: a plurality of transmit/receive integrated multichannel module (TRIMM) cards, each TRIMM card including power and beamforming signals, where power and beamforming signals are connected in parallel to each modular antenna array block, a plurality of radiators for radiating antenna signals having a radiator face, a radome integrated with the plurality of radiators and interfacing directly to the radiator face, where the radome does not extend beyond the radiator face, and a frame for supporting the TRIMM cards.
In some embodiments, the disclosed invention is a modular phased array antenna that includes a plurality of modular antenna array blocks assembled together as a single antenna array. Each modular antenna array block includes: a plurality of transmit/receive integrated multichannel module (TRIMM) cards, each TRIMM card including power and beamforming signals, where power and beamforming signals are connected in parallel to each modular antenna array block, a plurality of radiators for radiating antenna signals having a radiator face, a radome integrated with the plurality of radiators and interfacing directly to the radiator face, where the radome does not extend beyond the radiator face, and a frame for supporting the TRIMM cards. Moreover, each modular antenna array block contains its own power and electronics cards and is capable of being configured as a stand-alone radar antenna array
In some embodiments, each modular antenna array block receives cooling independent with respect to cooling of other modular antenna array blocks,
In some embodiments, the frame is made of aluminum and attaches to a back structure made of steel on its back side, and each modular antenna array block further comprises an intermediate aluminum frame between the frame and the back structure to minimize array face distortion due to coefficient of thermal expansion.
In some embodiments, each modular antenna array block further comprises a plurality of adjustment mechanisms located at corners of said each modular antenna array building block for adjustment of said each modular antenna array building block in six degree of freedom.
In some embodiments, each modular antenna array block may further include threaded bosses along vertical sides and bottom of the frame for allowing said each modular antenna array block to be securely fastened to every adjacent modular antenna array block and/or a plurality of actuators configured to adjust a position of said each modular antenna array block.
These and other features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings.
In some embodiments, the disclosed invention is one or more of a modular and stackable antenna.
In some embodiments, the modular antenna structure and supporting electronics 302 reside within the volume behind the active antenna region 306, allowing one antenna array block to be stacked on top of, or next to, another antenna array block to create a single, larger monolithic antenna with no disruption of antenna array's lattice spacing. Power, cooling and beamforming 304 are connected in parallel to each modular antenna array block and therefore, eliminating the dependency of one antenna array block on the adjacent antenna array block. In other words, each building block receives coolant, power, and control signals in parallel and thus the power and beamforming circuitries are internal to each block, which eliminates any beamforming RF interconnections between modular building blocks.
The modular and stackable antenna blocks may be combined (e.g. stacked on, or placed next to) together to produce any desired size antenna array 300 and thus minimizing the initial investment costs while maintaining the ability to easily increase the size and sensitivity and thus capability of the antenna array, as required by different applications. Each modular and stackable antenna block operates the same regardless of the assembled array size. This way, additional antenna blocks can be added later without impact to the existing system's structure, support electronics or thermal management.
As shown, the modular and stackable antenna array 500 utilizes a new radome design that is integrated with (part of) the radiator 506 within each modular building block. Unlike radome designs that have structural attachments that extend beyond the active face of the array, the new radome design of the disclosed invention interfaces directly to the radiator face 506 for each MRA (three MRAs are shown separated here) and fits within the MRA's lattice spacing, so the MRAs can be stacked or placed adjacent to each other without impacting the overall array's lattice spacing or RF performance
The integrated radome 502 is the same size as radiator assembly 506 comprising of multiple radiating elements and attaches directly to the radiator assembly, rather than attaching to extra structure around the perimeter of the radiator. The integrated radome allows the array structure to be the same size as the active array face 504, rather than extending beyond the edges of the face. Since the MRA structure does not extend beyond active area of the array face 504, the modular building blocks can be stacked with no interruptions in the block spacing between adjacent stacked modular building blocks. All modular building blocks can operate the same way regardless of the array size.
In contrast, many conventional antenna arrays use a radome that is independent of the radiators and therefore the radome assembly bolts to structure and extends beyond the edges of the active radiating area, as shown in
In some embodiments, to minimize array face distortion due to coefficient of thermal expansion (CTE) mismatch between aluminum frame 610 and steel back structure 606, an intermediate aluminum frame 604 mates between the two. This intermediate structure acts as a deflection buffer for the array face, where the intermediate frame is configured and mounted in such a fashion to deflect as much as needed during thermal expansion without transferring these deflections to the array face, which can impact system performance. The antenna's electronic hardware and functionality including the radiators, beamformers, TRIMMs, DREXs, and AC/DC power conversion 608 are accommodated in a modular and easily replaceable rack 609. A plurality of adjustment mechanisms 612 located at the corners of the modular building block 600 allow adjustment of the building block in six degree of freedom. A flanged interface 614 provides the physical interface between the (front) frame and back structures, while allowing access forward to the MBB housing 610 which supports and aligns the MBBs to access each individual MBB for maintenance.
The radar building blocks 600 may be stacked vertically and/or horizontally to form a larger radar array face, by a plurality of forward adjustment/alignment mechanisms 612a and aft rear adjustment mechanisms 612b. In some embodiments, the disclosed invention, utilizes a unique 3-dimensional (3D) alignment mechanisms for installing each antenna module. The 3D alignment mechanisms 612a and 612b located at each corner of the back structure allow adjustments in all six degrees of freedom, (x, y, z & rotational) to ensure proper positioning. Section alignment may be performed manually or automated.
As shown in
The flatness of the array plate 1000 to which the radiators are mounted determines the angles at which the RF waves are emitted to hold each array plate “flat” to a certain flatness tolerance to ensure the RF waves interfere constructively at the predetermined angles in front of the antenna array. Stacking multiple radar building blocks introduces a further challenge for this flatness requirement, as each individual array face needs to be precisely aligned with each other's faces to create one uniform, coplanar array face. An array plate is attached to a front of each modular antenna array block, and a plurality of interlocking joints a plurality of interlocking joints, such as a lap joint or tongue and groove features, positioned on top and bottom of the array plate are configured to allow for adjustment and alignment of said each modular antenna array block. For example, a built-in tongue-and-groove joint 1003 allows adjustment for this alignment. In some embodiments, the back of the radar building block can be manipulated to pivot the upper array plate on the lower one, thus achieving alignment.
Due to the proximity of the electronic hardware, there is a significant amount of weight load in the front of the array and the array plate 1000 functions as a load path for this weight load. The tongue-and-groove aspect of this joint acts to interlock each array plate to the one above/below it. This helps the interconnected array plates act like a monolithic structure that the load can pass through smoothly, without the use of fasteners. In addition, the tongue-and-groove aspect of this joint is designed such that the upper array 1010 can be assembled vertically to the lower array 1012, despite the arrays being tilted back at a significant angle, as illustrated in
In addition to the tongue and groove features, the array plate joints are castellated to match the radiator castellation. The array plate is designed such that the array plate will always lie proud of the radiators to prevent radiator-on-radiator contact during assembly and alignment, thus significantly reducing the risk of damaging a radiator.
The thermal support blocks are designed such that they are compliant along one direction, and stiff in the other two directions. They are positioned such that the compliant direction of each block points directly at a single “thermal center” in the structure. In some embodiments, there are two types of thermal support blocks, the first design 1100, incorporates the array tilt angle to complete the load path through the array plate, and the second design 1101 is a simpler lattice structure that sits under the flat areas of the stacked radar structure. These blocks allow the stacked radar structure to deflect freely in the worst case thermal scenarios while maintaining their structure.
The architecture of the disclosed invention enables stacking and assembling radar building blocks together vertically and/or horizontally to form a larger and higher performance radar system, which can at a later date become larger by adding additional building blocks to increase capability, minimize radar down time while growing to the larger sizes, and deploy radar systems rapidly to acquire available critical equipment as soon as possible.
The approach of the disclosed invention allows the radar system to be modular and scalable at the array level. The radar module assembly section becomes the basic building block, containing all of the antenna's electronic hardware and functionality including the radiators, beamformers, TRIMMs, DREXs, and power conversion. Once assembled, they combine to become the full size radar antenna array as well as a self-supporting structural building block. Each module building block receives coolant, power, and control signals in parallel and is a stand-alone mini-radar. The individual building blocks can be integrated with electronics and tested off-site, then shipped to the deployment region for installation.
Once at the deployment site, the building blocks can be assembled vertically and horizontally as they arrive and be aligned into proper positions to create the full size radar antenna array. This minimizes initial cost while maintaining the ability to upgrade capability when needed. The approach also minimizes radar down time while it is being grown to a larger sizes, which is a key requirement for tactically critical equipment. The radar system can also be deployed faster than systems where all electronics are integrated on-site and thus reducing the time it takes to get critical equipment available since the building blocks are delivered to the deployment site as tested known-good equipment.
It will be recognized by those skilled in the art that various modifications may be made to the illustrated and other embodiments of the invention described above, without departing from the broad inventive step thereof. It will be understood therefore that the invention is not limited to the particular embodiments or arrangements disclosed, but is rather intended to cover any changes, adaptations or modifications which are within the scope of the invention as defined by the appended drawings and claims.
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