Antenna subarray block with heat dissipation properties

Abstract

An apparatus providing a rectangular N x M antenna element subarray block having first and second opposing major surfaces and first and second opposing ends, with antenna elements located at the first end of the block, a first inlet connector in the first major surface for flow of liquid coolant, and a first outlet connector on the first major surface for flow of the liquid coolant, a cold plate between the first inlet connector and the first outlet connector to enable the flow of the liquid coolant from the first inlet connector to the first outlet connector, the first inlet connector configured to enable the flow of the liquid coolant into the block in a direction perpendicular to the first major surface.

Description

[Technical field]

[0001] The present invention relates to a device and array having a rectangular block of N x M antenna element sub-arrays. Summary of the Invention [Problem to be solved by the invention]

[0002] As is known in the art, systems that include electronics can generate large amounts of heat that must be dissipated. For example, a phased array radar system has an antenna array for transmitting and / or receiving signals. For example, an Active Electronically Steerable Array (AESA) may require half-wavelength spacing between antenna elements to achieve grating lobe free beam steering for scan angles greater than 60 degrees. At high frequencies (e.g., greater than 50 GHz), it becomes difficult to integrate the electronics required for a high-power AESA into a two-dimensional half-wavelength grid while simultaneously dissipating the heat generated by, for example, a high-power GaN MMIC power amplifier. [Means for solving the problem]

[0003] The disclosed embodiments provide a method and apparatus for antenna element subarray blocks having liquid coolant flowing in and out of the blocks to increase heat dissipation compared to conventional configurations. In embodiments, the subarray blocks can be stacked such that adjacent blocks have coolant inlets and outlets connected to each other. The inlet and outlet connections establish coolant flow into and out of the blocks in a direction perpendicular to the major surfaces of the blocks.

[0004] In some embodiments, a subarray block may have N x M antenna elements, where M is equal to 1. A compact cold plate may have microchannels for forced liquid cooling to effectively remove heat from the subarray. An example subarray block has 8 x 1 elements. The subarray blocks may have connectors configured to provide power, RF, and control signals between the subarray blocks. In some embodiments, beamformer subarray circuitry may be provided on the subarray blocks. In some embodiments, the antenna array may include a utility block that allows for an increase in the overall size of the array.

[0005] In some embodiments, subarray blocks can be stacked to provide an antenna array for an AESA system that supports half-wave element spacing at frequencies of 100 GHz and above and is also effective at dissipating heat generated by each element. For example, cooling can be achieved for a GaN MMIC amplifier generating 1 W of RF power in CW mode at a frequency of 100 GHz. Known subarray elements cannot provide adequate cooling for systems with this level of power at half-wave element spacing of 100 GHz.

[0006] According to one feature, an apparatus includes a rectangular N x M antenna element subarray block having first and second opposing major surfaces and first and second opposing ends with antenna elements located at the first end of the block; a first inlet connector in the first major surface for flow of liquid coolant; a first outlet connector on the first major surface for flow of the liquid coolant; and a cold plate between the first inlet connector and the first outlet connector for enabling flow of the liquid coolant from the first inlet connector to the first outlet connector. The first inlet connector is configured to enable flow of the liquid coolant into the block in a direction perpendicular to the first major surface.

[0007] According to another feature, the array includes a plurality of N x M antenna element subarray blocks, the block including: opposing first and second major surfaces of the block; opposing first and second ends of the block; an antenna located at the first end of the block; inlet and outlet connectors on the first major surface for a flow of liquid coolant; and inlet and outlet connectors on the second major surface for the flow of the liquid coolant, the inlet and outlet connectors configured to provide a flow of the liquid coolant from the block to the block. The block further includes a cold plate between the inlet and outlet connectors for enabling the flow of the liquid coolant through the cold plate. The inlet connector on the first major surface is configured to enable the flow of the liquid coolant to the plurality of blocks in a direction perpendicular to the first major surface.

[0008] The foregoing features of the present disclosure can be more fully understood from the following description of the drawings, as well as from the specification itself. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is a block diagram of an example system having sub-array blocks in accordance with an exemplary embodiment of the present disclosure. [Diagram 2] 2 is a partially transparent perspective view of an example N x M element subarray block according to an exemplary embodiment of the present disclosure. [Figure 2A] 3 illustrates a cold plate that may form part of the sub-array block of FIG. 2 according to an exemplary embodiment of the present disclosure. [Diagram 3] FIG. 2 is a partially transparent perspective view of an exemplary stack of N x M element subarray blocks in accordance with an exemplary embodiment of the present disclosure. [Figure 4A] FIG. 2 is a partially transparent perspective view of an example stack of N×M element sub-array blocks within an enclosure according to an exemplary embodiment of the present disclosure. [Figure 4B]FIG. 2 is a partially transparent perspective view of an example stack of N×M element sub-array blocks within an enclosure according to an exemplary embodiment of the present disclosure. [Diagram 5] 1 is a partially transparent perspective view of an exemplary utility block that may form part of an array in accordance with an exemplary embodiment of the present disclosure. [Figure 5A] FIG. 2 is a partially transparent perspective view of an example utility block connected to a stack of N x M element sub-array blocks in accordance with an example embodiment of the present disclosure. [Figure 6] 1 is a schematic diagram of an array having an exemplary utility block that may form part of the array in accordance with an exemplary embodiment of the present disclosure. [Figure 7] FIG. 1 is a schematic diagram of an array having transmit and receive arrays for first and second polarizations implemented using example N×M element subarray blocks in accordance with an exemplary embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] 1 illustrates an example of a radar system 100, such as an active electronically scannable array (AESA) system. The system 100 includes an antenna array 102 having subarrays formed from stacked subarray blocks in accordance with an exemplary embodiment of the present disclosure. The antenna array 102 is coupled to a transmitter system 104 and a receiver system 106. The radar system 100 can transmit signals that can be reflected by a target 108 and received by the antenna array 102. In some embodiments, the transmitter and receiver systems are physically separated from one another. In some embodiments, the system is passive and no signals are transmitted.

[0011] A waveform generator 110 may generate signals for the transmitter system 104. Signal returns may be received at the receiver system 106 and processed in a signal processor 112. A detection and tracking module 114 is configured to detect targets, such as target 108, from the processed signal returns and track the targets. Radar information, which may include target tracking, may be displayed on a display 116.

[0012] 2 shows an example of an N x M element subarray block 200, also referred to as a "brick." In some embodiments, M=1, such that the antenna subarray block includes N x 1 elements 202. In some embodiments, the elements 202 of the subarray block 200 include integrated circuits configured for high radiation efficiency. In one embodiment, the integrated circuit includes a W-band GaN MMIC with an on-chip antenna, for example, with an element spacing of λ / 2 (e.g., 1.5 mm for a 1 mm MMIC width).

[0013] A substrate 204, such as a multi-layer substrate, connects to the subarray elements 202. An integrated circuit 206, such as a beamformer circuit, may be mounted on a cold plate 208. The beamformer circuit 206 may generate beams from the upconverted LO and IF signals in a manner well known in the art. A first connector 210 may provide power, IF, inter-board communication, and / or clock signals for adjacent subarray blocks in the stack. A second connector 212 may provide similar signals to adjacent blocks on the opposite side of the subarray. A third connector 214, which may be located at one end of the block 200, may provide, for example, a local oscillator (LO) signal.

[0014] The cold plate 208 may include microchannels for fluid flow. An input flow connection 218 may be located on one side of the cold plate 208, and an output flow connection 220 may be located on the other side of the cold plate. In an embodiment, a liquid such as water enters the input flow connection 218 at a relatively low temperature, travels through the microchannels, and exits the output flow connection 220 after absorbing heat, increasing the temperature of the liquid. The seals 222, 224 of the input and output flow connections 218, 220, respectively, provide a closed connector in the absence of adjacent blocks. In the presence of adjacent connected blocks, the seals 222, 224 provide a fluid path between the adjacent blocks. The input and output flow connections 218, 220 are configured to allow liquid to flow into and out of the blocks in a direction perpendicular to the major surfaces of the blocks.

[0015] In some embodiments, the subarray elements or blocks are generally rectangular in shape in the form of a printed circuit board configured to be inserted into a slot in the enclosure. As used herein, a "major surface" of a subarray element refers to the surface with the largest surface area. For example, a typical PCB has top and bottom major surfaces and four sides or edges. A rectangular PCB has a first end and a second end. An example block has dimensions W=12 mm, H=1.5 mm, L=45 mm.

[0016] There is a relatively large aspect ratio between the cold plate 208 surface area and the RF radiating surface area of ​​the element 202 that facilitates thermal management. Forced microchannel liquid cooling within the cold plate 208 not only supports the heat flux generated, for example, in digital beamformers, but also provides efficient heat removal to enable effective thermal management of high power GaN MMICs and heat generating DSP components.

[0017] In some embodiments, the seals 222, 224 of the coolant connections 218, 220 can be provided as O-rings that provide brick-to-brick seals and flex when assembled. It is understood that the seals 222, 224 can be constructed of any practical size, shape, and material to meet the needs of a particular application. In some embodiments, the brick-to-brick seals are closed by compressing the stacked bricks together using a frame plate. The frame plate provides mechanical support for the bricks and the fasteners that pass through fastener openings in the bricks and in the frame plate. The compression force forces the O-ring into a shallow recess opening. The shallow recess opening is machined into the cold plate to facilitate placement of the O-ring. The portion of the cold plate surrounding the O-ring protrudes slightly above the surface of the cold plate to act as a stop when the bricks are compressed together by the fasteners. Small guide pins and corresponding guide holes are machined into the cold plate to increase the stiffness of the assembled array. These pins and holes engage when the brick is compressed, locking the brick against lateral movement. The seal can be opened by removing the compression force between the fastener and the brick.

[0018] The portion of the subarray block 200 of FIG. 2 shown in FIG. 2A includes a diffusion bonded cold plate 208 with microchannels 209 that provide paths between input and output flow connections 218, 220. A microchannel cold plate refers to a multi-pass parallel flow heat exchanger with inlet and outlet manifolds, e.g., multi-port tubes with hydraulic diameters less than 1 mm, and fins. Microchannels can provide high heat transfer ratios, low coolant charge, compact size, and low airside pressure drop compared to finned tube heat exchangers. An example of a cold plate with microchannels is shown in U.S. Pat. No. 7,443,354, the disclosure of which is incorporated herein by reference.

[0019] FIG. 3 illustrates a stack 300 of eight connected 8×1 subarray blocks, which may include the subarray block 200 of FIG. 2. The illustrated stack 300 provides an 8×8 subarray. In one embodiment, cooled liquid enters the inlet 218 in a direction perpendicular to the top major surface of the topmost subarray element, and heated liquid exits through the outlet 220. A seal (not explicitly shown) on the bottom major surface of the bottommost block 200 of the stack 300 is closed. As previously described, cooled liquid enters each block in the stack at the inlet connector 218, passes through the microchannels of the cold plate 208, and heated liquid exits each block at the outlet connector 220.

[0020] In some embodiments, the block cooling liquid inlets 218, 220 are perpendicular to the major surface of the cold plate 208 to allow for larger channel diameters for higher flow rates and provide an optimal geometry for stacking of elements. Board-to-board connectors 210, 212 provide high density interconnects for distribution of power, clock, control signals and data between the subarrays. For example, push-on SMPM connectors can provide a suitable interface for LO distribution.

[0021] 4A and 4B show a partially transparent perspective view of an example of an enclosure 400 having a stack 400. The enclosure 400 may include the subarray stack 300 of FIG. 3 with an enclosure coolant inlet 402 and an enclosure coolant outlet 404. The antenna elements 202 may be spaced λ / 2 in the y and z axes. Connections 406 at the bottom of the enclosure may provide power, IF, communications, etc.

[0022] In one example embodiment, the stacked subarray blocks within the enclosure 400 are pulled tightly into physical contact using small diameter screws or tension wires that pass through openings perpendicular to the subarray plane. Guide grooves and alignment pins can be used to provide additional rigidity. It will be appreciated that a wide variety of mechanical devices and structures can be used to secure the stacked subarrays within the rack.

[0023] FIG. 5 shows an example of a utility block 500 that allows for an increase in the size of the array. For example, for stacks larger than 32×32 elements, the utility block 500 can be used to allow array sizes larger than 10,000 elements. While there may be some tradeoffs between array size and beam spoiling by the utility block, the advantages of larger array sizes will be readily apparent to one skilled in the art. FIG. 5A shows a utility block 500 connected to a stack 501 of subarray elements above the utility block and a stack 503 of subarray elements below the block.

[0024] The utility block 500 may include a main coolant inlet 502 and a main coolant outlet 504. The main coolant inlet 502 may receive coolant exiting the utility block via a first stack coolant connector 506 to allow coolant to flow to a stack of subarray elements, as previously described. The main coolant outlet 504 may allow heated coolant to flow out of the utility block 500. The second coolant connector 508 may receive heated coolant from the stack of subarray elements, as previously described. The utility block 500 may further include third and fourth coolant connectors 510, 512 at the bottom of the block for connection to a stack below the utility block. The main connector 514 may provide connection to the main systems of the utility block 500 for power, IF, communications, etc.

[0025] FIG. 6 shows an example array 600 with utility blocks 602 shown in shaded locations in the array. The illustrated array 600 is 128 x 128 elements, with 86% of the array populated with active antenna elements. In an embodiment, the utility blocks 602 do not transmit or receive signals. The utility blocks 602 improve cooling capacity by increasing coolant flow to and from the array. The improved cooling capacity allows for larger arrays to be used.

[0026] 7 shows an example of a dual polarized W-band AESA 700 with continuous wave (CW) simultaneous transmit and receive capabilities. The array 700 includes an H polarized transmit subarray 702, a V polarized transmit subarray 704, a V polarized 706 receive subarray, and an H polarized receive subarray 708. In some embodiments, a 32 x 32 element subarray is used.

[0027] It will be appreciated that a wide variety of N x M element subarrays, polarization types and configurations may be selected to meet the needs of a particular application.

[0028] The disclosed embodiments provide a subarray element architecture compatible with half-wave element spacing at frequencies as high as 100 GHz and above. A compact cold plate with microchannels for forced liquid cooling provides effective heat removal. The cold plate can be fabricated, for example, by diffusion bonding or ultrasonic bonding. The cooling liquid is distributed, for example, to 8 x 1 or 12 x 1 element subarrays.

[0029] Example embodiments of the present disclosure may be applied to transmit and receive systems that use relatively high-power components that require significant heat dissipation capabilities. Exemplary systems include radar systems, communication networks such as 5G wireless networks, etc.

[0030] Having described exemplary embodiments of the present disclosure, it will be apparent to one of ordinary skill in the art that other embodiments incorporating these concepts may also be used. The embodiments contained herein should not be limited to the disclosed embodiments, but rather should be limited only by the spirit and scope of the appended claims. All publications and references cited herein are expressly incorporated herein by reference in their entirety.

[0031] Elements of different embodiments described herein may be combined to form other embodiments not specifically described above. Various elements that are described in the context of a single embodiment may also be provided separately or in any suitable subcombination. Other embodiments not specifically described herein are also within the scope of the following claims.

Claims

1. a rectangular block of N×M antenna element subarrays, the block having first and second opposing major surfaces and first and second opposing ends, with an antenna element located at the first end of the block; an inlet connector passing through said block between said first major surface and said second major surface for flow of liquid coolant; an outlet connector passing through the block between the first and second major surfaces for the flow of the liquid coolant; and a cold plate having embedded microchannels between the inlet connector and the outlet connector for allowing flow of the liquid coolant from the inlet connector to the outlet connector; An apparatus comprising: the inlet connector is configured to permit flow of the liquid coolant into the block in a direction perpendicular to the first major surface.

2. The apparatus of claim 1 , further comprising a first seal for the inlet connector and a second seal for the outlet connector.

3. The apparatus of claim 2 , wherein the first seal and the second seal are configured to provide respective connections to seals on adjacent blocks within an enclosure.

4. The apparatus of claim 1, wherein the apparatus has a stack of the blocks of the subarray, each of the blocks configured to cause the liquid coolant to flow from one of the plurality of blocks to another via its respective inlet connector and outlet connector.

5. The apparatus of claim 1 , wherein M=1.

6. The apparatus of claim 1 , further comprising an electrical connector at a second end of the block.

7. an array including a plurality of blocks of N×M antenna element subarrays; Each of the blocks comprises: first and second opposing major surfaces of the block; a first end and a second end of the block; an antenna element located at the first end of the block; inlet and outlet connectors on said first and second major surfaces for flow of liquid coolant; Including, an inlet connector on the first major surface and an inlet connector on the second major surface communicate through the block, and an outlet connector on the first major surface and an outlet connector on the second major surface communicate through the block, the inlet connector and the outlet connector are configured to provide a flow of the liquid coolant from the block to the block; Each of the blocks further comprises: a cold plate having microchannels embedded therein between the inlet connector and the outlet connector to enable flow of the liquid coolant through the cold plate; the inlet connector is configured to permit flow of the liquid coolant into the plurality of blocks in a direction perpendicular to the first major surface. array.

8. The array of claim 7 , further comprising a seal for each of the inlet and outlet connectors.

9. The array of claim 8 , wherein the seals are configured to provide respective connections to the seals on adjacent blocks within an enclosure.

10. The array of claim 7, wherein M=1.

11. The array of claim 7, wherein at least some of the plurality of blocks further include an electrical connector on the second end of the block.

12. The array of claim 7, wherein at least some of the plurality of blocks further include a beamformer integrated circuit on the cold plate.

13. further comprising a plurality of utility blocks in the array configured to receive the flow of liquid coolant and provide the liquid coolant; the utility block does not include a radiating antenna element; The array of claim 7.

14. 8. The array of claim 7, wherein the antenna elements of the array are spaced at wavelength λ / 2 spacing for frequencies up to 100 GHz.

15. 8. The array of claim 7, wherein the antenna elements of the array comprise MMICs with on-chip antennas.

16. 8. The array of claim 7, wherein the array comprises more than 10,000 antenna elements.

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