Modular architecture for scalable phased array radars

This application is a Divisional Application of and claims priority to U.S. patent application Ser. No. 13/230,271, filed Sep. 12, 2011 and entitled “MODULAR ARCHITECTURE FOR SCALABLE PHASED ARRAY RADARS” and which is also a Continuation Application of and claims priority to U.S. patent application Ser. No. 12/948,858 filed Nov. 18, 2010 and entitled MODULAR ARCHITECTURE FOR SCALABLE PHASED ARRAY RADARS. The applications cited in this paragraph are incorporated herein by reference in their entirety.

This invention was made with Government support under Contract Number N00024-09-C-5313 awarded by the Department of the Navy. The United States Government has certain rights in the invention.

As is known in the art, a phased array antenna includes a plurality of active circuits spaced apart from each other by known distances. Each of the active circuits is coupled through a plurality of phase shifter circuits, amplifier circuits and/or other circuits to either or both of a transmitter and receiver. In some cases, the phase shifter, amplifier circuits and other circuits (e.g., mixer circuits) are provided in a so-called transmit/receive (T/R) module and are considered to be part of the transmitter and/or receiver.

The phase shifters, amplifier and other circuits (e.g., T/R modules) often require an external power supply (e.g., a DC power supply) to operate correctly. Thus, the circuits are referred to as “active circuits” or “active components.” Accordingly, phased array antennas which include active circuits are often referred to as “active phased arrays.”

Active circuits dissipate power in the form of heat. High amounts of heat can cause active circuits to be inoperable. Thus, active phased arrays must be cooled. In one example heat-sink(s) are attached to each active circuit to dissipate the heat.

In one aspect, a radar array assembly includes two or more vertical stiffeners each having bores with threads and a first radar module. The first radar module includes radar transmit and receive (T/R) modules and a chassis having channels configured to receive a coolant. The chassis includes shelves having ribs. The ribs have channels configured to receive the coolant and the ribs form slots to receive circuit cards disposed in parallel. The circuit cards include the T/R modules. The chassis also includes set screws attached to opposing sides of the chassis. The set screws have bores to accept fasteners to engage the threads on a corresponding one of the two or more vertical stiffeners. The first radar module is configured to operate as a stand-alone radar array.

In another aspect, a radar module includes radar transmit and receive (T/R) modules and a chassis having channels configured to receive a coolant. The chassis includes shelves having ribs. The ribs have channels configured to receive the coolant. The ribs form slots to receive circuit cards disposed in parallel. The circuit cards include the T/R modules. The radar module is configured to perform as a standalone radar array and perform with other radar modules to form a radar array.

In a further aspect, a radar radiator panel, includes a radome, cyanate ester quartz (CEQ) coupled to the radome and a stacked assembly coupled to the CEQ, the stacked assembly comprising a thermal conductive layer configured to facilitate a transfer of heat to the radome.

One or more of the aspects above may include one or more of the following features. The radar array module may include a dual digital receiver exciter (DDREX) module, a synthesizer module and an auxiliary power module disposed in the slots. The radar array assembly may include an array plate having a first side and a second side opposite the first side, a radiator panel attached to the first side of the array plate and RF jumpers attached to the second side of the array plate. The array plate may be coupled to the vertical stiffeners. The first radar array module may include a digital receiver and exciter (DREX) backplane coupled to the chassis, an RF backplane coupled to the DREX backplane and an overlap beamformer having a first side and a second side opposite the first side. The first side of the overlap beamformer coupled to the RF backplane and the second side of the overlap beamformer coupled to the RF jumpers. The radiator panel may include stacked assemblies each comprising a thermal conductive layer. The thermal conductive layer may include at least one of aluminum and copper. The thermal conductive layer may be greater than 1 mil. The thermal conductive layer may be about 60 mils. The radar array assembly may include a second radar module configured to be substantially the same as the first radar module. A set screw may include a notch configured to be engaged by a flat tip screwdriver.

FIGS. 1A and 1B are plan views of a radar module.

FIGS. 2A and 2B are plan views of different sized radar array frame structures.

FIG. 3A is an exploded view of the radar module and a portion of a radar array frame structure.

FIG. 3B is a side-view the radar module attached to the radar array frame structure.

FIG. 4A is a plan view of a set screw.

FIG. 4B is a cross-sectional view of the set screw securing the chassis to a vertical stiffener.

FIG. 5A is a plan view of a radiator panel.

FIG. 5B is a plan view of a radiator housing with one stacked-patch assembly.

FIG. 5C is a plan view of the radiator housing taken at the line FIG. 5C in FIG. 5B .

FIG. 5D is a cross-sectional view of an array plate and the radiator panel.

FIG. 5E a cross-sectional view of the array plate and the radiator panel depicting heat flow.

FIGS. 6A and 6B are plan views of a cooling chassis.

FIG. 7 is a view of a supply cold plate depicting an example of coolant flow.

FIG. 8 is a view of a return cold plate depicting an example of coolant flow.

FIG. 9A is a top view of a top cold plate depicting an example of coolant flow.

FIG. 9B is a bottom view of the top cold plate depicting an example of coolant flow.

FIGS. 9C and 9D are side views of the top cold plate.

Existing phased array architectures contain cooling systems, power systems and signal distribution systems that are sized to match the size of the array. Resizing the array requires a redesign of each of those systems. The cooling system is redesigned to control device operating temperatures and thermal gradients to avoid negatively impacting performance. This system redesign is costly and takes a significant amount of time to implement. Also, even if the number of line replaceable units (LRUs) could be increased (e.g., to accommodate a larger array size), the number of LRUs will be limited by power and control limitations because each row of LRUs is cooled and powered in series.

As described herein, a radar module may be used as a building block to form various radar array sizes. Each radar module is fabricated to be identical. In particular, each radar module receives in parallel the necessary coolant, power and control signals necessary to be a stand-alone antenna array. Thus, by merely adding radar modules together, the radar array sizes are scalable. In one example, the radar modules can form multiple array sizes from two feet to thirty-two feet and beyond.

Referring to FIGS. 1A and 1B , a radar module 10 includes a chassis 11 that includes a top cold plate 12 , a supply manifold 14 a with an input port 42 , a return manifold 14 b with an output port 22 , a bottom cold plate 16 and a front plate 18 . The chassis 11 is configured to hold LRUs (e.g., circuit cards) such as transmit/receive integrated microwave modules (TRIMMs) 32 that include transmit/receive (T/R) modules ( 33 ), dual digital receiver exciter (DDREX) modules 34 , a synthesizer module 36 , and an auxiliary/controller module 40 .

The chassis 11 performs a cooling function. For example, the T/R modules 33 produce high amounts of heat which must be dissipated or else the active circuits (e.g., power amplifiers) will cease to operate properly. The supply manifold 14 a includes channels that receive coolant at the port 42 . The coolant is circulated through out the chassis 11 and removed via the return manifold 14 b out the port 22 . In particular, the chassis 11 performs as a heat sink drawing the heat away from the active circuits (e.g., in the T/R modules 33 ). The chassis 11 includes set screws 46 attached to the supply manifold 14 a and to the return manifold 14 b.

In operation the radar module radiates energy in a direction R. In particular, the T/R modules 33 radiate energy in the R direction.

The radar module 10 also includes a digital receiver and exciter (DREX) backplane 54 attached to the front plate 18 , an RF backplane 50 attached to the DREX backplane and overlap beamformers 52 attached to the RF backplane.

Referring to FIGS. 2A and 2B , radar modules 10 may be secured inside honey-combed structures called radar array frame structures. For example, a radar array frame structure 80 includes an array plate 62 with vertical stiffeners 60 and horizontal stiffeners 58 attached to the array plate. The vertical stiffeners 60 and the horizontal stiffeners 58 form cavities (e.g., a cavity 61 ) in which a single radar module 10 may be disposed inside. In one example, the radar module 10 rests on a horizontal stiffener 58 and is secured to the vertical stiffeners using set screws 46 attached to the supply manifold 14 a and the return manifold 14 b.

The radar array frame structure 80 in FIG. 2A can include thirty-six radar modules 10 with an active area of about eight square meters. A radar array frame structure 80 ′ in FIG. 2B can hold one hundred and sixteen radar modules 10 with an active area of about thirty-seven square meters. In other examples, the horizontal stiffeners 58 are not used; but rather, each radar module 10 is secured to two vertical stiffeners 60 .

Referring to FIGS. 3A and 3B , a radiator panel 70 is attached to one side of the array plate 62 and RF jumpers 64 are attached to the opposite side of the array plate. The RF jumpers 64 are attached to the overlap beamformers 52 . In one example, each overlap beamformer is coupled to four RF jumpers 64 .

As shown in FIG. 3A a coolant supply line 74 is coupled to the port 42 and a coolant return line 72 is coupled to the port 22 . Data is supplied to the radar module 10 by a line 76 and power is supplied by a line 78 .

Referring to FIGS. 4A and 4B , the set screws 46 are used to attach the radar module 10 to the vertical stiffeners 60 . A set screw 46 includes threads 57 that engage with threads in the supply manifold 14 a . The set screw 46 includes a notch 49 configured to be engaged by a flat tip screwdriver to adjust its depth to reduce a horizontal tolerance h t between the supply manifold 14 a and the vertical stiffener 60 . The set screw 46 also includes a bore 51 to receive a bolt 53 with washer 55 to secure the radar module 10 to the vertical stiffener 60 by having the threads 57 of the bolt 53 engage threads 59 of the vertical stiffener. The set screws 46 are used to compensate for the different horizontal tolerances h t as each radar module 10 is being secured with the radar array framework 80 . Though only set screws 46 on the supply manifold 14 a are described in FIGS. 4A and 4B , one of ordinary skill in the art would recognize that set screws 46 function similarly on the return manifold 14 b.

Referring to FIGS. 5A to 5E , the radiator panel 70 includes a housing 96 (e.g., an aluminum housing) with a stacked-path assembly 98 (sometimes called an element) in each cavity 100 of the housing; a radome 102 ; cyanate ester quartz (CEQ) 104 ; and an epoxy 106 to bond the stacked-patch 98 to the housing 96 . Each stacked-patch assembly 98 includes an epoxy 108 , a multi-layer RF circuit card 110 , foam 112 , which includes cross-linked polymers, and a thermal conductive layer 114 (e.g., aluminum, copper and so forth). In one example, the thermal conductive layer 114 is greater than 1 mil (e.g., about 60 mils). RF energy is supplied to the RF circuit card 110 via a connector (not shown) that protrudes thru the housing 90 .

For simplicity, in FIGS. 5B and 5C , the radiator panel 70 does not include the radome 102 , the CEQ 104 or the epoxy 106 . Also, FIGS. 5B and 5C only depict a single stacked-patch assembly 98 in one cavity 100 while the remaining cavities are empty. In one example, the radiator panel 70 is about two feet by two feet and holds about one hundred forty-four stacked path assemblies 98 .

The CEQ 104 adds structural integrity by protecting the radiator panel 70 from damage from objects colliding with the radiator panel 70 . In one example, the objects may include hail.

The configuration of the stacked-patch assembly 98 contributes to adding an anti-icing feature to the radiator panel 70 . Even though the coolant in the chassis 11 cools the T/R modules 33 there is some excess thermal energy that transfers to the array plate 62 . The excess thermal energy (depicted by arrows H in FIG. 5E ) flows from the array plate 62 through the housing 96 and through the thermal conductive layers 114 to the radome 102 . The thermal conductive layers 114 with a high thermal conductivity directs the heat to the radome 102 . The thermal energy transferred to the radome 102 is sufficient enough to maintain its surface at a temperature above freezing so that ice and snow does not accumulate on the radome 102 .

Referring to FIGS. 6A and 6B , the chassis 11 may be configured as chassis 11 ′ that includes a supply manifold 14 a ′ and a return manifold 14 b ′ that are orientated on opposite sides than the supply manifold 14 a and the return manifold 14 b respectively in the chassis 11 . Similarly, the chassis 11 ′ includes a top cold plate 12 ′ that is oriented opposite to the top cold plate 12 and a bottom cold plate 16 ′ that is oriented opposite to the bottom cold plate 16 . The chassis 11 ′ also includes large cold plates 118 and small cold plates 122 . These cold plates 118 , 122 include cooling ribs 124 that include channels (not shown) to carry coolant. Gaps between the cooling ribs 124 form slots 126 that hold the TRIMMs 32 in a parallel configuration, which contributes to a more efficient cooling of the T/R modules 33 . The slots 126 are also configured to hold the DDREX modules 34 , the synthesizer module 36 and the auxiliary/controller module 40 .

Referring to FIGS. 7 and 8 , the supply cold plate 14 a ′ receives coolant through the port 42 and flows through a channel 130 as indicated by arrows D. The return cold plate 14 b ′ includes a channel 152 that carries coolant in a flow as indicated by arrows D to the port 22 . In one example, the port 42 receives propylene glycol water (PGW) coolant at 10 gallons per minute (gpm) and 20° C. and the port 22 returns the PGW coolant at 30° C.

Referring to FIGS. 9A to 9D , the top cold plate 12 ′ includes an upper channel 172 a running along a top portion 212 of the top cold plate 12 ′ and a lower channel 172 b running along a bottom portion 214 of the top cold plate 12 ′. The upper channel 172 a and the lower channel 172 b are connected by channels 172 c.

The processes described herein are not limited to the specific embodiments described. Elements of different embodiments described herein may be combined to form other embodiments not specifically set forth above. Other embodiments not specifically described herein are also within the scope of the following claims.