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EP-4391219-B1 - FLUID COOLED RADAR SYSTEM

EP4391219B1EP 4391219 B1EP4391219 B1EP 4391219B1EP-4391219-B1

Inventors

  • ROMANACCI, Luca
  • ATTARDO, Alice
  • FATTORI, ALBERTO

Dates

Publication Date
20260506
Application Date
20231221

Claims (10)

  1. A radar system comprising a stack of functional printed circuit boards arranged in layers, housed in a common enclosure (30) of the radar system, wherein the stack of functional printed circuit boards layers comprises at least two sub-stacks (2, 3) and at least two cooling plates (20, 27), wherein each of the cooling plates (20, 27) is in thermal contact with one of the sub-stacks (2, 3), and wherein at least two cooling plates (20, 27) are thermally connected with each other by cooling fluid transferring means (47, 48, 49) and are connected to a heat sink (50) of the radar system, the heat sink (50) external to the common enclosure (31), wherein the stack of functional layers comprises an analog sub-stack (2) and a digital sub-stack (3) and the cooling plates comprise an analog cooling plate (20) and a digital cooling plate (27), in thermal contact with the analog sub-stack (2) and the digital sub-stack (3) respectively, and wherein the analog sub-stack comprises at least an analog receiver (6), an electrical power controller (7), a solid-state power amplifier (8), and an antenna (11).
  2. A radar system comprising a stack of functional printed circuit boards arranged in layers, housed in a common enclosure (30) of the radar system, wherein the stack of functional printed circuit boards layers comprises at least two sub-stacks (2, 3) and at least two cooling plates (20, 27), wherein each of the cooling plates (20, 27) is in thermal contact with one of the sub-stacks (2, 3), and wherein at least two cooling plates (20, 27) are thermally connected with each other by cooling fluid transferring means (47, 48, 49) and are (50) connected to a heat sink (50) of the radar system, the heat sink external to the common enclosure (31), wherein the stack of functional layers comprises an analog sub-stack (2) and a digital sub-stack (3) and the cooling plates comprise an analog cooling plate (20) and a digital cooling plate (27), in thermal contact with the analog sub-stack (2) and the digital sub-stack (3) respectively, and wherein the analog cooling plate (20) and the digital cooling plate (27) are hydraulically connected in series.
  3. A radar system according to claim 1, characterized in that the cooling fluid transferring means (47, 48, 49) connecting the cooling plates are arranged within the external outline of the stack of functional layers.
  4. A radar system according to claim 1, characterized in that the digital sub-stack comprises at least a radar control circuit (22), a digital signal processor (23), a radio frequency distributor (24), a reference signal generator (25) and a power distribution unit (26).
  5. A radar system according to claim 1, characterized in that the common enclosure (30) is air and water tight.
  6. A radar system according to claim 1, characterized in that at least one of the functional printed circuit boards comprises electrical connectors arranged on one side only of the board whereby the board is capable of being dismantled from the stack independently of the adjacent boards.
  7. A radar system according to claim 6, characterized in that at least one of the functional printed circuit boards comprises an open cutout (17), around a cooling fluid transferring means (47, 48, 49) and/or an electric connecting element (15).
  8. A method of cooling a radar system comprising the steps of: - arranging the active components of the radar system in a plurality of functional printed circuit boards layers arranged in a stack within a common enclosure; - grouping the functional layers of the stack in at least a first sub-stack comprising functional elements of analog type and a second sub-stack comprising functional elements of digital type, - providing at least a first and a second cooling plate, wherein said first cooling plate is in thermal exchange contact with at least one of the functional layers of the first sub-stack and wherein said second cooling plate is in thermal exchange contact with at least another one of the functional layers of the second sub-stack, - removing heat from one or more functional layers of the first sub-stack by said first cooling plate with a cooling fluid; - removing heat from one or more functional layers of the second sub-stack by said second cooling plate with a cooling fluid, - connecting said first and second cooling plates to a heat sink external to the common enclosure; - transporting heat from at least one of said first and second cooling plate to the heat sink; flowing the cooling fluid first through the cooling plate contacting the sub-stack grouping analog type functional elements and then through the cooling plate contacting the sub-stack grouping digital type functional elements.
  9. A method of cooling a radar system according to claim 8, characterized in that it comprises circulating the cooling fluid through said first and second cooling plates and through the external heat sink.
  10. A method of cooling a radar system according to claim 8, characterized in that it the cooling fluid is water.

Description

The present invention provides a radar system with an improved cooling solution that saves on volume and offers modularity for use The invention pertains to the field of cooling radar components, specifically the cooling of active electronically scanned array radars (AESA radars) and other phased array radar types. AESA radars are well known in the art and are widely used in civil and military applications. AESA radars may be used in airborne, naval or terrestrial installations; in particular, terrestrial installations include static installation, in buildings or the like, and mobile installation, on vehicles or the like. In such radars the various active components are mounted on printed circuit boards (PCB). During use many of the PCB mounted components produce an amount of heat which require cooling in order to enable the components to remain operational. Modern AESA radars usually comprise a stack of individual or laminated layers, in particular layers of PCBs, each of which comprising a multitude of electronic and electric components such as different digital and analog chips and chipsets, RF transceiver and receivers, resistors, transistors, diodes, capacitors and other mounted components. Other functional layers such as passive layers dedicated to shielding the circuits can also be present within the stack. Such close packing of components in a stack produces an excess amount of heat, which requires an efficient heat removal capability. US9172145 discloses an active electronically scanned array (AESA) radar system, comprising a stack of laminated PCBs. The system further comprises a heat sink having a surface configured to be in thermal contact with a plurality of electronics (i.e. both passive and active circuits) disposed on an external surface of a multilayer mixed signal printed wiring board (PWB). A second surface of the heat sink is provided with plurality of heat spreading elements such as fins, in order to remove excess heat from the entirety of the stack. The applicant observes that, because of the different cooling efficiencies on the PCBs, due to their distance to the cooling plate, components that are in direct contact with the cooling plate will be cooled more efficiently than any components located on the opposing side of the stack, far from the cooling plate. The presence of heat spreading elements such as fins on one of the heat sink surfaces requires such heat sink to be exposed to air or the like, and increases bulkiness of the assembly. Additionally, this approach is believed to be generally feasible for radar systems of lower power consumption only, due to the restricted heat removal capabilities the single cooling plate offers, and likely not even possible in case of high-power systems, such as an 800W system. US6292364 discloses a radar system and a cooling method including spray cooling of the relevant modules. The patent application US2022272846 discloses a radar system including two circuit boards, for antenna elements and power circuitry, wherein the two circuit boards are mounted on opposite sides of a heat sink. The heat sink has internal channels providing pathways for a coolant fluid such as air or water, connected into a coolant system comprising a pump or fan and optionally a heat exchanger which is separate from the heat sink. The patent application US2005146479 discloses a low profile active electronically scanned antenna for radar systems comprising an array of beam control tiles, wherein cooling of the various components is achieved by a pair of planar forced air heat sink members located on either side of the array of beam control tiles. The patent application US2011102296 discloses an RF (radio frequency) aperture cold plate in heat transfer proximity to heat-generating elements of an RF antenna system, including waveguides forming an opening through the RF aperture cold plate. The patent application US2008169973 discloses a thermal control arrangement for an array antenna including first and second liquid cooled cold plates defining a generally planar volume; an array of antenna elements and a transmit/receive arrangement is in thermal communication with such first and second liquid cooled cold plates. The patent US10547117 discloses an active electronically scanned array including a linear -to-circular polarizer, transmit-receive modules and one or more a liquid cooled manifold configured in a stacked arrangement to provide cooling during high power operation. The patent application US2012314370 discloses translating hinges which can be used in radar systems having array antennas with cold plates using liquid cooling, A problem of the prior art solutions is to provide an effective cooling of the various components of a radar system, even in case of high-power systems, without increasing the overall size of the system and by maintaining the electronic circuitry protected from external environment. A stacked architecture of a radar system enables to achieve high