Systems and methods for signal communication with expandable modular network nodes

Abstract

To provide systems and methods for signal communication with suitable, scalable, modular network nodes.SOLUTION: A radio frequency (RF) aperture includes an interface board. An array of electrically conductive tapered projections has bases disposed on a front side of an interface printed circuit board and extending away from the front side of the interface printed circuit board. RF circuitry is disposed at the back side of the interface board and is electrically connected with the electrically conductive tapered projections. The RF circuitry is disposed on the back side of the interface board and is electrically connected to the array of electrically conductive tapered protrusions on the front side of the interface board.SELECTED DRAWING: None

Description

[Background technology]

[0001] This application claims the benefit of U.S. Provisional Application No. 62 / 842,816, filed May 3, 2019, and entitled "SYSTEMS AND METHODS FOR SIGNAL COMMUNICATION WITH SCALABLE, MODULAR NETWORK NODES," which claims the benefit of U.S. Provisional Application No. 62 / 839,131, filed April 26, 2019, and entitled "SYSTEMS AND METHODS FOR SIGNAL COMMUNICATION WITH SCALABLE, MODULAR NETWORK NODES," which claims the benefit of U.S. Provisional Application No. 62 / 839,125, filed April 26, 2019, and entitled "SYSTEMS AND METHODS FOR SIGNAL COMMUNICATION WITH SCALABLE, MODULAR NETWORK NODES." U.S. Provisional Application No. 62 / 842,816, filed May 3, 2019, is incorporated herein by reference in its entirety. U.S. Provisional Application No. 62 / 839,131, filed April 26, 2019, is incorporated herein by reference in its entirety. U.S. Provisional Application No. 62 / 839,125, filed April 26, 2019, is incorporated herein by reference in its entirety.

[0002] (background) The following relates to radio frequency (RF) technology areas, RF transmitter technology areas, RF receiver technology areas, RF transceiver technology areas, broadband RF transmitters, receivers, and / or transceivers technology areas, RF communications technology areas, and related technology areas.

[0003] Steinbrecher's U.S. Patent No. 7,420,522, entitled "Electromagnetic Radiation Interface System and Method," discloses a broadband RF aperture as follows: "An electromagnetic radiation interface suitable for use with radio frequencies is provided. The surface comprises a plurality of metallic conical bristle bodies. A corresponding plurality of termination sections are provided such that each bristle body terminates with the termination section. The termination sections may comprise an electrical resistor to capture substantially all of the electromagnetic energy received by each individual bristle body, thereby preventing reflections from the surface of the interface. Each termination section may also comprise an analog-to-digital converter for converting energy from each bristle body into a digital word. The bristle bodies may be mounted on a ground plane having a plurality of holes therethrough. A plurality of coaxial transmission lines may extend through the ground plane to interconnect the plurality of bristle bodies to the plurality of termination sections." Some improvements are disclosed herein. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Patent No. 7,420,522 Summary of the Invention [Means for solving the problem]

[0005] (Brief summary) According to certain illustrative embodiments disclosed herein, a radio frequency (RF) aperture comprises an interface substrate having a front side and a back side; an array of conductive tapered protrusions having bases disposed on the front side of the interface substrate and extending away from the front side of the interface substrate, the conductive tapered protrusions being hollow and one or more electronic components being disposed inside the hollow conductive tapered protrusions; and RF circuitry disposed on the back side of the interface substrate and electrically connected to the array of conductive tapered protrusions on the front side of the interface substrate.

[0006] According to certain exemplary embodiments disclosed herein, the RF aperture includes an interface substrate having a front side and a back side, an array of conductive tapered protrusions having a base disposed on the front side of the interface substrate and extending away from the front side of the interface substrate, and RF circuitry disposed on the back side of the interface substrate and electrically connected to the array of conductive tapered protrusions on the front side of the interface substrate, The conductive tapered protrusions of the array of conductive tapered protrusions include a first set of equally sized conductive tapered protrusions arranged in a linear array and a second set of conductive tapered protrusions disposed between the conductive tapered protrusions of the first set of conductive tapered protrusions.

[0007] According to certain example embodiments disclosed herein, the RF aperture comprises an interface substrate having a front side and a back side, an array of conductive tapered protrusions having a base disposed on the front side of the interface substrate and extending away from the front side of the interface substrate, a dielectric filler disposed between the conductive tapered protrusions, and RF circuitry disposed on the back side of the interface substrate and electrically connected to the array of conductive tapered protrusions on the front side of the interface substrate.

[0008] According to certain example embodiments disclosed herein, the RF aperture comprises an interface substrate having a front side and a back side, an array of faceted conductive tapered protrusions having bases disposed on the front side of the interface substrate and extending away from the front side of the interface substrate, and RF circuitry disposed on the back side of the interface substrate and electrically connected to the aperture pixels, the RF circuitry comprising differential RF receiving and / or transmitting elements defined by adjacent facets of adjacent pairs of the faceted conductive tapered protrusions.

[0009] According to certain illustrative embodiments disclosed herein, an RF aperture comprises: an interface substrate having a front side and a back side; an array of solid conductive tapered protrusions having bases disposed on the front side of the interface substrate and extending away from the front side of the interface substrate, the bases having threaded openings; threaded fasteners passing through the openings in the interface substrate and threading into the threaded openings in the bases of the solid conductive tapered protrusions to secure the solid conductive tapered protrusions to the interface substrate; and RF circuitry disposed on the back side of the interface substrate and electrically connected to aperture pixels comprising differential RF receive and / or transmit elements defined by adjacent pairs of the solid conductive tapered protrusions.

[0010] According to certain illustrative embodiments disclosed herein, an RF aperture comprises: an interface substrate having a front side and a back side; an array of hollow conductive tapered protrusions having bases disposed on the front side of the interface substrate and extending away from the front side of the interface substrate, the hollow conductive tapered protrusions having central cylindrical supports disposed inside the hollow protrusions, the central cylindrical supports having threaded openings; threaded fasteners passing through the openings in the interface substrate and threaded into the threaded openings in the central cylindrical supports of the hollow conductive tapered protrusions to secure the hollow conductive tapered protrusions to the interface substrate; and RF circuitry disposed on the back side of the interface substrate and electrically connected to aperture pixels comprising differential RF receiving and / or transmitting elements defined by adjacent pairs of hollow conductive tapered protrusions.

[0011] According to some exemplary embodiments disclosed herein, an RF aperture includes an interface substrate having a front side and a back side, an array of conductive tapered protrusions having bases disposed on the front side of the interface substrate and extending away from the front side of the interface substrate, the conductive tapered protrusions having a central cylindrical support disposed inside the hollow protrusions, and RF circuitry disposed on the back side of the interface substrate and electrically connected to aperture pixels comprising differential RF receive and / or transmit elements defined by adjacent pairs of the conductive tapered protrusions. Each conductive tapered protrusion includes a dielectric structure having a tapered receptacle and a conductive tapered plate mating within the tapered receptacle of the dielectric structure, the conductive tapered plate defining a facet of the conductive tapered protrusion.

[0012] According to some exemplary embodiments disclosed herein, an RF aperture includes an interface substrate having a front side and a back side, an array of conductive tapered protrusions having bases disposed on the front side of the interface substrate and extending away from the front side of the interface substrate, the conductive tapered protrusions having a central cylindrical support disposed inside the hollow protrusions, RF circuitry disposed on the back side of the interface substrate and electrically connected to aperture pixels comprising differential RF receive and / or transmit elements defined by adjacent pairs of the conductive tapered protrusions, and a radome having tapered-protrusion-shaped recesses. The conductive tapered protrusions are disposed within the tapered-protrusion-shaped recesses of the radome and may comprise sheet metal stamped into the tapered-protrusion-shaped recesses.

[0013] According to certain example embodiments disclosed herein, the RF aperture includes:

[0014] According to some example embodiments disclosed herein, an RF aperture configured to operate at an RF wavelength comprises an interface substrate having a front side and a back side; an array of conductive tapered protrusions having bases disposed on the front side of the interface substrate and extending away from the front side of the interface substrate; RF circuitry disposed on the back side of the interface substrate and electrically connected to aperture pixels comprising differential RF receive and / or transmit elements defined by adjacent pairs of the conductive tapered protrusions; and standoffs having a height greater than the RF wavelength, wherein the faceted conductive tapered protrusions are mounted on respective standoffs.

[0015] According to some example embodiments disclosed herein, an RF aperture includes an interface substrate having a front side and a back side, the interface substrate being a dielectric substrate or printed circuit board (PCB) without a ground plane, an array of conductive tapered protrusions having bases disposed on the front side of the interface substrate and extending away from the front side of the interface substrate, and RF circuitry disposed on the back side of the interface substrate and electrically connected to aperture pixels comprising differential RF receive and / or transmit elements defined by adjacent pairs of conductive tapered protrusions. The RF circuitry includes a PCB with a ground plane oriented perpendicular to the interface substrate, and RF components mounted on the vertical PCB.

[0016] According to certain example embodiments disclosed herein, the RF aperture comprises:

[0017] According to certain example embodiments disclosed herein, the RF aperture comprises:

[0018] According to certain example embodiments disclosed herein, the RF aperture comprises: [Brief explanation of the drawings]

[0019] Any quantitative dimensions shown in the drawings are to be understood as non-limiting illustrative examples. Unless otherwise indicated, the drawings are not to scale and any aspect of the drawings is shown as being to scale, and the scale shown is to be understood as non-limiting illustrative examples.

[0020] [Figure 1] 1 and 2 diagrammatically illustrate front and side cross-sectional views, respectively, of an exemplary RF aperture implemented as a differentially segmented aperture (DSA). [Figure 2] 1 and 2 diagrammatically illustrate front and side cross-sectional views, respectively, of an exemplary RF aperture implemented as a differentially segmented aperture (DSA).

[0021] [Figure 3] FIG. 3 shows a schematic block diagram of a single QUAD subassembly of the DSA of FIGS. 1-4.

[0022] [Figure 4] FIG. 4 diagrammatically illustrates a front view of the interface printed circuit board (i-PCB) of the DSA of FIGS. 1-3, including vias and mounting holes, and diagrammatically indicating the locations of the balun and resistor pads.

[0023] [Figure 5] FIG. 5 schematically illustrates a rear view of the enclosure of the DSA of FIGS. 1-4, including the RF connections, controls, and power connectors shown diagrammatically.

[0024] [Figure 6] FIG. 6 diagrammatically illustrates a side cross-sectional view of one embodiment of a conductive tapered protrusion, along with a diagrammatic representation of the connection of a balanced port of a chip balun between two adjacent conductive tapered protrusions.

[0025] [Figure 7] 7-10 diagrammatically illustrate additional embodiments of conductive tapered protrusions. [Figure 8] 7-10 diagrammatically illustrate additional embodiments of conductive tapered protrusions. [Figure 9] 7-10 diagrammatically illustrate additional embodiments of conductive tapered protrusions. [Figure 10] 7-10 diagrammatically illustrate additional embodiments of conductive tapered protrusions.

[0026] [Figure 11] 11 and 12 show embodiments in which the conductive tapered protrusion of the RF aperture is hollow and one or more electronic components are disposed inside the hollow conductive tapered protrusion. [Figure 12]11 and 12 show embodiments in which the conductive tapered protrusion of the RF aperture is hollow and one or more electronic components are disposed inside the hollow conductive tapered protrusion.

[0027] [Figure 13] FIG. 13 diagrammatically illustrates an exploded view of another illustrative RF aperture assembly.

[0028] [Figure 14] 14-17 diagrammatically show several example layouts of conductive tapered protrusions across the area of ​​an RF aperture. [Figure 15] 14-17 diagrammatically show several example layouts of conductive tapered protrusions across the area of ​​an RF aperture. [Figure 16] 14-17 diagrammatically show several example layouts of conductive tapered protrusions across the area of ​​an RF aperture. [Figure 17] 14-17 diagrammatically show several example layouts of conductive tapered protrusions across the area of ​​an RF aperture.

[0029] [Figure 18] 18-24 show side cross-sectional views of RF aperture embodiments employing a dielectric fill material disposed between adjacent conductive tapered protrusions to tailor RF trapping performance for transmit and / or receive operations. [Figure 19] 18-24 show side cross-sectional views of RF aperture embodiments employing a dielectric fill material disposed between adjacent conductive tapered protrusions to tailor RF trapping performance for transmit and / or receive operations. [Figure 20] 18-24 show side cross-sectional views of RF aperture embodiments employing a dielectric fill material disposed between adjacent conductive tapered protrusions to tailor RF trapping performance for transmit and / or receive operations. [Figure 21]18-24 show side cross-sectional views of RF aperture embodiments employing a dielectric fill material disposed between adjacent conductive tapered protrusions to tailor RF trapping performance for transmit and / or receive operations. [Figure 22] 18-24 show side cross-sectional views of RF aperture embodiments employing a dielectric fill material disposed between adjacent conductive tapered protrusions to tailor RF trapping performance for transmit and / or receive operations. [Figure 23] 18-24 show side cross-sectional views of RF aperture embodiments employing a dielectric fill material disposed between adjacent conductive tapered protrusions to tailor RF trapping performance for transmit and / or receive operations. [Figure 24] 18-24 show side cross-sectional views of RF aperture embodiments employing a dielectric fill material disposed between adjacent conductive tapered protrusions to tailor RF trapping performance for transmit and / or receive operations.

[0030] [Figure 25] FIG. 25 shows another illustrative RF aperture assembly.

[0031] [Figure 26] FIG. 26 shows an RF aperture comprising a conductive tapered protrusion disposed on a curved (eg, radial) surface.

[0032] [Figure 27] FIG. 27 shows a schematic diagram of a network employing DSA.

[0033] [Figure 28] FIG. 28 illustrates diagrammatically a suitable processing node for use in conjunction with the embodiment of FIG.

[0034] [Figure 29] 29-36 illustrate an embodiment of a conductive tapered protrusion that is a solid protrusion. [Figure 30] 29-36 illustrate an embodiment of a conductive tapered protrusion that is a solid protrusion. [Figure 31] 29-36 illustrate an embodiment of a conductive tapered protrusion that is a solid protrusion. [Figure 32] 29-36 illustrate an embodiment of a conductive tapered protrusion that is a solid protrusion. [Figure 33] 29-36 illustrate an embodiment of a conductive tapered protrusion that is a solid protrusion. [Figure 34] 29-36 illustrate an embodiment of a conductive tapered protrusion that is a solid protrusion. [Figure 35] 29-36 illustrate an embodiment of a conductive tapered protrusion that is a solid protrusion. [Figure 36] 29-36 illustrate an embodiment of a conductive tapered protrusion that is a solid protrusion.

[0035] [Figure 37] 37-39 illustrate several alternative faceted conductive tapered protrusion geometries. [Figure 38] 37-39 illustrate several alternative faceted conductive tapered protrusion geometries. [Figure 39] 37-39 illustrate several alternative faceted conductive tapered protrusion geometries.

[0036] [Figure 40] 40-41 illustrate an embodiment of a conductive tapered protrusion that is hollow. [Figure 41] 40-41 illustrate an embodiment of a conductive tapered protrusion that is hollow.

[0037] [Figure 42] 42-46 illustrate an embodiment of a conductive tapered protrusion that includes a dielectric structure and a tapered plate. [Figure 43] 42-46 illustrate an embodiment of a conductive tapered protrusion that includes a dielectric structure and a tapered plate. [Figure 44] 42-46 illustrate an embodiment of a conductive tapered protrusion that includes a dielectric structure and a tapered plate. [Figure 45] 42-46 illustrate an embodiment of a conductive tapered protrusion that includes a dielectric structure and a tapered plate. [Figure 46] 42-46 illustrate an embodiment of a conductive tapered protrusion that includes a dielectric structure and a tapered plate.

[0038] [Figure 47] 47-49 illustrate the mounting of the conductive tapered protrusions of FIGS. 42-46 on an interface substrate. [Figure 48] 47-49 illustrate the mounting of the conductive tapered protrusions of FIGS. 42-46 on an interface substrate. [Figure 49] 47-49 illustrate the mounting of the conductive tapered protrusions of FIGS. 42-46 on an interface substrate.

[0039] [Figure 50] 50-54 illustrate an embodiment of a conductive tapered protrusion constructed by folding a cutout in sheet metal. [Figure 51] 50-54 illustrate an embodiment of a conductive tapered protrusion constructed by folding a cutout in sheet metal. [Figure 52] 50-54 illustrate an embodiment of a conductive tapered protrusion constructed by folding a cutout in sheet metal. [Figure 53] 50-54 illustrate an embodiment of a conductive tapered protrusion constructed by folding a cutout in sheet metal. [Figure 54] 50-54 illustrate an embodiment of a conductive tapered protrusion constructed by folding a cutout in sheet metal.

[0040] [Figure 55] FIG. 55 illustrates one embodiment of a conductive tapered protrusion constructed by stamping sheet metal into a radome that defines the tapered protrusion configuration.

[0041] [Figure 56] FIG. 56 illustrates potential RF interference in a DSA due to an interface board with a ground plane.

[0042] [Figure 57] FIG. 57 illustrates an embodiment employing standoffs to mitigate potential RF interference as described with reference to FIG.

[0043] [Figure 58] 58-63 illustrate an embodiment employing RF circuitry with vertical printed circuit boards (PCBs) to mitigate potential RF interference as described with reference to FIG. [Figure 59] 58-63 illustrate an embodiment employing RF circuitry with vertical printed circuit boards (PCBs) to mitigate potential RF interference as described with reference to FIG. [Figure 60] 58-63 illustrate an embodiment employing RF circuitry with vertical printed circuit boards (PCBs) to mitigate potential RF interference as described with reference to FIG. [Figure 61] 58-63 illustrate an embodiment employing RF circuitry with vertical printed circuit boards (PCBs) to mitigate potential RF interference as described with reference to FIG. [Figure 62] 58-63 illustrate an embodiment employing RF circuitry with vertical printed circuit boards (PCBs) to mitigate potential RF interference as described with reference to FIG. [Figure 63] 58-63 illustrate an embodiment employing RF circuitry with vertical printed circuit boards (PCBs) to mitigate potential RF interference as described with reference to FIG.

[0044] [Figure 64] FIG. 64 illustrates an exploded view of a DSA including a radome and vertical PCB as described with reference to FIGS. 58-63.

[0045] [Figure 65] FIG. 65 illustrates a five-sided housing or enclosure for the DSA embodiment of FIG.

[0046] [Figure 66] 66-81 illustrate various embodiments of RF circuitry suitable for use with the DSA embodiments disclosed herein. [Figure 67] 66-81 illustrate various embodiments of RF circuitry suitable for use with the DSA embodiments disclosed herein. [Figure 68] 66-81 illustrate various embodiments of RF circuitry suitable for use with the DSA embodiments disclosed herein. [Figure 69] 66-81 illustrate various embodiments of RF circuitry suitable for use with the DSA embodiments disclosed herein. [Figure 70] 66-81 illustrate various embodiments of RF circuitry suitable for use with the DSA embodiments disclosed herein. [Figure 71] 66-81 illustrate various embodiments of RF circuitry suitable for use with the DSA embodiments disclosed herein. [Figure 72] 66-81 illustrate various embodiments of RF circuitry suitable for use with the DSA embodiments disclosed herein. [Figure 73] 66-81 illustrate various embodiments of RF circuitry suitable for use with the DSA embodiments disclosed herein. [Figure 74] 66-81 illustrate various embodiments of RF circuitry suitable for use with the DSA embodiments disclosed herein. [Figure 75]66-81 illustrate various embodiments of RF circuitry suitable for use with the DSA embodiments disclosed herein. [Figure 76] 66-81 illustrate various embodiments of RF circuitry suitable for use with the DSA embodiments disclosed herein. [Figure 77] 66-81 illustrate various embodiments of RF circuitry suitable for use with the DSA embodiments disclosed herein. [Figure 78] 66-81 illustrate various embodiments of RF circuitry suitable for use with the DSA embodiments disclosed herein. [Figure 79] 66-81 illustrate various embodiments of RF circuitry suitable for use with the DSA embodiments disclosed herein. [Figure 80] 66-81 illustrate various embodiments of RF circuitry suitable for use with the DSA embodiments disclosed herein. [Figure 81] 66-81 illustrate various embodiments of RF circuitry suitable for use with the DSA embodiments disclosed herein. DETAILED DESCRIPTION OF THE INVENTION

[0047] (Detailed explanation) 1 and 2, front and side cross-sectional views are shown of an illustrative radio frequency (RF) aperture including an interface printed circuit board (i-PCB) 10 having a front side 12 and a back side 14, respectively, and an array of conductive tapered protrusions 20 having bases 22 disposed on and extending away from the front side 12 of the i-PCB 10. While the illustrative i-PCB 10 is shown in FIG. 1 as having dimensions of 5 inches by 5 inches, this is merely a non-limiting illustrative example of a small RF aperture. FIG. 1 shows a front view of the RF aperture with an inset at the upper left showing a perspective view of one conductive tapered protrusion 20. This illustrative embodiment of conductive tapered protrusion 20 has a square cross-section with a larger square base 22 and an apex that does not extend to a full tip, but rather terminates at a flat apex 24 (in other words, the conductive tapered protrusion 20 in the inset has a frusto-conical shape). This is merely an illustrative example; more generally, conductive tapered protrusion 20 can have any type of cross-section (e.g., square, as in the inset, or circular, or hexagonal, or octagonal, etc.). Apex 24 can be flat, as in the inset example, or can reach a sharp point, or can be rounded, or have some other apex geometry. The rate of tapering as a function of height (i.e., the distance "above" base 22 when apex 24 is at its maximum "height") can be constant, as in the inset example, or the rate of tapering can vary with height; for example, the rate of tapering can increase with increasing height to form protrusions with rounded tops, or decrease with increasing height to form protrusions with more pointed tips. Similarly, as shown in most detail in FIG. 1, the illustrative array of conductive tapered protrusions 20 is a rectilinear array with regular rows and orthogonal regular columns; however, the array may have other symmetries, e.g., hexagonal symmetry, octagonal symmetry, etc.In the illustrative example of the inset, a square base 22 and square apex 24 lead to a conductive tapered protrusion 20 having four flat, sloping sidewalls 26; however, other sidewall shapes are contemplated, for example, if the base and apex are circular (or the base is circular and the apex reaches to a point), the sidewalls would be sloping or tapered cylinders, for a hexagonal base and hexagonal or pointed apex, there would be six sloping sidewalls, etc.

[0048] 1 and 2, and with further reference to FIG. 3, the RF aperture further comprises RF circuitry including, in an illustrative embodiment, chip baluns 30 mounted on the backside 14 of the i-PCB 10. Each chip balun 30 has a balanced port P that is electrically connected to two neighboring conductive tapered protrusions of the array of conductive tapered protrusions via electrical feedthroughs 32 passing through the i-PCB 10. B (See FIGS. 3 and 6.) Each chip balun 30 further includes an unbalanced port P U (See FIGS. 3 and 6.) The exemplary RF network further includes an unbalanced port P U 3, an exemplary electrical configuration of the RF circuitry includes an RF power divider / combiner 40 for combining the outputs from the unbalanced port P U 1. The example employs a first level 1×2 RF power divider / combiner 401 that combines pairs of RF power dividers / combiners 401, and a second level 1×2 RF power divider / combiner 402 that combines the outputs of the pairs of first level RF power dividers / combiners 401. This is merely an illustrative approach, and other configurations are contemplated, such as using 1×3 (combining three lines), 1×4 (combining four lines), or higher combined RF power dividers / combiners, or various combinations thereof. The illustrative RF circuitry further provides a power supply to each unbalanced port P of chip balun 30. Uand the first-level 1×2 power divider 401. The signal conditioning circuit 42 connected to each unbalanced port includes an RF transmit amplifier T, an RF receive amplifier R, and RF switching circuitry including a switch RFS configured to switch between a transmit mode that operatively connects the RF transmit amplifier T to the unbalanced port and a receive mode that operatively connects the RF receive amplifier R to the unbalanced port.

[0049] With continued reference to FIGS. 1-3 and with further reference to FIGS. 4 and 5, a compact design (e.g., a 3-inch depth in the non-limiting illustrative example of FIG. 3) is achieved in part by employing one or more printed circuit boards (PCBs), including at least i-PCB 10. In the illustrative example shown in FIG. 3, chip baluns 30 are mounted on the backside 14 of i-PCB 10. Optionally, other electronic components may also be mounted on the backside of i-PCB 10, which has an array of conductive tapered protrusions 20 disposed on its front side 12. However, there may be insufficient footprint on i-PCB 10 to mount all of the RF circuitry electronics. In the illustrative embodiment, this is addressed by providing a second printed circuit board 50 positioned parallel to i-PCB 10 and facing the backside 14 of i-PCB 10. In other words, the second printed circuit board 50 is disposed on the (back) side 14 of the i-PCB 10, opposite the (front) side 12 of the i-PCB 10 on which the conductive tapered protrusions 20 are disposed. The RF circuitry comprises electronic components mounted on the second printed circuit board 50, which may also be referred to herein as a signal conditioning PCB or SC-PCB 50, in addition to or alternatively to electronic components mounted on the i-PCB 10 (typically on the back side 14 of the i-PCB, although it is also contemplated (not shown) that the RF circuitry components may be mounted on the front side of the i-PCB in the field space between the conductive tapered protrusions 20). If an SC-PCB 50 is provided, it is suitably secured in parallel to the i-PCB 10 by standoffs 54, as shown in FIG. 2, and a single-ended feedthrough 52 is provided to electrically interconnect the i-PCB 10 and the SC-PCB 50 (see FIG. 3). If the RF circuitry cannot fit onto the footprint of two PCBs 10, 50, a third (and optionally a fourth, and further) PCBs may be added (not shown) to accommodate the RF circuitry components.

[0050] FIG. 4 shows a front view of the i-PCB 10, including vias and mounting holes, and diagrammatically indicates the location of the balun 30 and resistor pads, as indicated in the legend shown in FIG. 4. (The resistors are used to terminate the unused sides of the pyramid to help lower the radar cross section.)

[0051] 2 and with further reference to FIG. 5, the illustrative RF aperture, in the illustrative embodiment, has an enclosure 58 affixed to the periphery of the i-PCB 10 so as to enclose the RF circuitry. This is just one illustrative arrangement, and other designs are contemplated, for example, both PCBs 10, 50 may be placed inside an enclosure (although such an enclosure should not include RF shielding extending forward so as to block the area of ​​the RF aperture). FIG. 5 diagrammatically illustrates a rear view of the RF aperture enclosure 58, showing a diagrammatically represented RF connector (or port) 60 (also shown or displayed in FIGS. 2 and 3 ), control electronics 62 (e.g., illustrative phased array beamsteering electronics 63, shown as a non-limiting illustration; these electronics 62, 63 may be mounted externally of the enclosure 58 and / or may be located inside the enclosure 58 to provide beneficial RF shielding), and a power connector 64 for providing power to operate the active components of the RF circuitry (e.g., operating power for the active RF transmit amplifiers T and active RF receive amplifiers R, and switch R). The particular arrangement of the various components 60, 62, 63, 64 across the area of ​​the rear side of the enclosure may vary widely from that shown in FIG. 5 , and these components may be located elsewhere; for example, the RF connector 60 may alternatively be located at the edge of the RF aperture, etc. It should also be understood that the RF aperture may be integrally constructed with some other component or system, for example, if the RF aperture is used as an RF transmitting and / or receiving element in a mobile ground station, maritime radio, unmanned aerial vehicle (UAV), etc., the enclosure 58 may be replaced by having the RF aperture built into the housing of the mobile ground station, maritime radio, UAV airframe, etc. In such a case, the RF connector 60 may also be replaced by a wired connection to the mobile ground station, maritime radio, UAV electronics, etc.

[0052] With particular reference to Figure 3, an exemplary electrical configuration for an exemplary RF network is shown. In this non-limiting exemplary example, the array of conductive tapered protrusions 20 is assumed to be a 5x5 array of conductive tapered protrusions 20, as shown in Figures 1 and 4. The balanced port P Bconnects adjacent (i.e., nearby) pairs of conductive tapered protrusions 20 of the array to receive a differential RF signal between two adjacent conductive tapered protrusions 20 (in a receive mode, or alternatively, to apply a differential RF signal between two adjacent conductive tapered protrusions 20 in a transmit mode). As detailed in U.S. Pat. No. 7,420,522 to Steinbrecher (incorporated herein by reference in its entirety), the tapering of the conductive tapered protrusions 20 presents a separation between two conductive tapered protrusions 20 that varies with "height," i.e., with the distance "above" the base 22 of the conductive tapered protrusions 20. This provides broadband RF capture, as a range of RF wavelengths can be captured, corresponding to the range of separation between adjacent conductive tapered protrusions 20 introduced by the tapering. The RF aperture is therefore a differentially segmented aperture (DSA), with differential RF receiving (or RF transmitting) elements corresponding to adjacent pairs of conductive tapered protrusions 20. These differential RF receiving (or transmitting) elements are referred to herein as aperture pixels. For an illustrative linear 5×5 array of adjacent conductive tapered protrusions 20, this means that there are four aperture pixels along each row (or column) of five conductive tapered protrusions 20. More generally, for a linear array of protrusions having N rows (or columns) of conductive tapered protrusions 20, there would be a corresponding N−1 pixels along the row (or column). FIG. 3 shows a QUAD subassembly, which is the interconnection of four pixel rows (or columns). Because there are four rows and four columns, this leads to 4×4 or 16 such QUAD subassemblies. Resistor pads are used as terminations for the unused edges of the surrounding pyramids to prevent unwanted reflections. Without the resistors mounted via the resistor pads, those surfaces would be left floating and could re-radiate incident RF energy, causing an enhanced radar cross section.

[0053] In the exemplary embodiment shown in FIG. 3, the second level 1×2 An RF power divider / combiner 402 connects to an RF connector 60 on the back side of the enclosure 58. Thus, as seen in FIG. 5, there are eight RF connectors for the eight QUAD subassemblies shown in FIGS. 4 and 5, such as row QUAD subassemblies N1, N2, N3, N4 and column QUAD subassemblies M1, M2, M3, M4. Gnd(N) row and Gnd(M) column are circuit grounds to allow a common path for current flow from captured RF energy along the perimeter sides of the pyramid. The use of QUAD subassemblies allows for a high level of flexibility in RF coupling to the RF aperture. For example, the illustrative phased array beamsteering electronics 63 selects the appropriate phase shifts for row QUAD subassemblies N1, N2, N3, N4.

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[0054] The described electronics, employing PCBs 10, 50, chip baluns 30, and active signal conditioning components (e.g., active transmit amplifiers T and receive amplifiers R), advantageously allow the RF aperture to be made small and lightweight. As will now be described, embodiments of the conductive tapered protrusion 20 further facilitate providing a small and lightweight broadband RF aperture.

[0055] FIG. 6 shows a side cross-sectional view of one illustrative embodiment in which each conductive tapered protrusion 20 is fabricated as a dielectric tapered protrusion 70 with a conductive layer 72 disposed on the surface of the dielectric tapered protrusion 70. The dielectric tapered protrusion may be composed of an electrically insulating plastic or ceramic material, such as acrylonitrile butadiene styrene (ABS), polycarbonate, etc., and may be manufactured by injection molding, three-dimensional (3D) printing, or other suitable techniques. The conductive layer 72 may be any suitable conductive material, such as copper, copper alloy, silver, silver alloy, gold, gold alloy, aluminum, aluminum alloy, etc., or may comprise a layered stack of different conductive materials, and may be coated onto the dielectric tapered protrusion 70 by vacuum evaporation, RF sputtering, or any other vacuum deposition technique. FIG. 6 shows an example in which solder points 74 are used to electrically connect the conductive layer 72 of each dielectric tapered protrusion 20 to its corresponding electrical feedthrough 32 passing through the i-PCB 10. FIG. 6 also illustrates the connection of the balanced port P of one chip balun 30 between two adjacent conductive tapered protrusions 20 via solder points 76. B Illustrative connections are also shown.

[0056] 7 and 8 show exploded side cross-sectional and perspective views, respectively, of an embodiment in which dielectric tapered protrusions 70 are integrally contained within a dielectric plate 80. A conductive layer 72 coats each dielectric tapered protrusion 70 but has insulating gaps 82 that provide galvanic isolation between neighboring dielectric tapered protrusions 20. The insulating gaps 82 can be formed after coating the conductive layer 72 by etching the coating away from the plate 80 between the conductive tapered protrusions 20, galvanically isolating the conductive tapered protrusions from one another. Alternatively, the insulating gaps 82 can be defined before coating by depositing a mask material (not shown) on the plate 80 between the conductive tapered protrusions 20 such that the coating does not coat the plate in the inter-conductive tapered protrusion insulating gaps 82, thereby galvanically isolating the conductive tapered protrusions from one another. As can be seen in the perspective view of FIG. 8, the result is that the dielectric plate 80 covers (and therefore occludes) the surface of the i-PCB 10, with the conductive tapered protrusions 20 extending away from the dielectric plate 80.

[0057] Referring particularly to Figure 7, in one approach for electrical interconnection, through-holes 82 pass through the illustrative plate 80 and the underlying i-PCB 10, and rivets, screws, or other conductive fasteners 32' pass through the through-holes 82 (note that Figure 7 is an exploded view), thus, when placed, forming electrical feedthroughs 32' that pass through the i-PCB 10. (Note that the perspective view of Figure 8 is simplified and does not depict the fasteners 32'.) The use of a dielectric plate 80 with an integral dielectric tapered protrusion 70 and combined fastener / feedthrough 32' advantageously allows the conductive tapered protrusions 20 to be placed with precision positioning and without soldering.

[0058] 6-8, a conductive coating 72 is disposed on the outer surface of the dielectric tapered protrusion 70. In this case, the dielectric tapered protrusion 70 may be either hollow or solid.

[0059] 9 and 10, because dielectric materials are substantially transparent to RF radiation, a conductive coating 72 may instead be coated on the inner surface of a (hollow) dielectric tapered protrusion 70. FIG. 9 shows a side cross-sectional view of such an embodiment, while FIG. 10 shows a perspective view. The embodiment of FIGS. 9 and 10 again employs a dielectric plate 80 including a dielectric tapered protrusion 70. As seen in FIG. 10, by coating the conductive coating 72 on the inner surface of the hollow dielectric tapered protrusion 70, this protects the conductive coating 72 from external contact by the dielectric plate 80 including the integral dielectric tapered protrusion 70. This may be useful in environments where weather may be an issue.

[0060] It should be understood that the various disclosed aspects are illustrative examples, and that the disclosed features may be variously combined or omitted in specific embodiments. For example, one of the illustrative examples of conductive tapered protrusion 20, or a variant thereof, may be employed without the QUAD subassembly circuitry configuration of FIGS. 2-5. Conversely, the QUAD subassembly circuitry configuration of FIGS. 2-5 or a variant thereof may be employed without the dielectric / coating configuration for conductive tapered protrusion 20. Similarly, chip balun 30 may or may not be used in specific embodiments, etc.

[0061] 11 and 12, further embodiments (e.g., scalable modular substrates) of the multiple sensor elements / pyramids 20 of the DSA 102 are described. The sensor elements / pyramids can be formed, for example, as an array on the front side 12 of the circuit board 10 and serve as a radiation interface. The sensor elements / pyramids 20 of FIGS. 11 and 12 each include multiple conductive plates 90 (FIG. 12) that together form a pyramid, and / or the sensor elements / pyramids can each be formed from a single plate 91 (FIG. 11), for example, wrapped around in a conical manner. In some embodiments, each sensor element / pyramid 20 is hollow, i.e., includes a void 92. The void 92 may be formed by an inner portion of either the multiple plates 90 and / or the single conical plate 91. This occurs, for example, when the sensor elements / pyramids 20 are supported from an outer portion, creating a void 92 in the center. In one embodiment, the multiple plates 90 of a sensor element / pyramid are adjacent to each other but cannot touch. In other words, the conductive plates of the sensor element / pyramid can form a gap 94 (FIG. 12). Similarly, the single conical plate 91 can have an upper opening or gap 95. Gaps 94, 95 can exist between the plates and / or between the plates and the support of the fixture containing or holding the sensor element / pyramid plates of the DSA. In some embodiments, the sensor element / pyramid 20 can be formed from a solid material. The surfaces 90, 91 of the plates forming the sensor element / pyramid can be used for conductivity (e.g., deep in the skin). In other words, the surfaces of the sensor element / pyramid 20 can be used to transmit current, for example, from a wavelength or RF signal, and the resistance of the sensor element / pyramid can increase (i.e., attenuation) as a result of the current being applied to the surface of the sensor element / pyramid. The plates 90, 91 can be formed from any highly conductive material. In some embodiments, the sensor element / pyramid plates 90, 91 may be formed from anything other than a conductive material, for example, a conductive material can be printed or wound onto a dielectric plate, for example, as shown in Figures 6-10.For example, a conductive material can be spray coated onto the plate that forms the sensor element / pyramid. The thickness of the coating can be varied to achieve a desired skin depth. The embodiment of Figures 11 and 12 further includes a conductor or electronic component 96 on the front side 12 of the circuit board 10. The embodiment of Figure 12 further includes a bend 97 and the conductor or electronic component 96 defined at the intersection of the bottom edge of the plate 90.

[0062] Continuing with reference to FIGS. 11 and 12 , some embodiments contemplate utilizing the air gap 92 defined by the hollow conductive tapered protrusion 20 to accommodate one or more electronic components 100 disposed on the front side 12 of the printed circuit board 10. Electrical vias, i.e., feedthroughs 102, passing through the i-PCB 10 provide electrical communication between the front-side electronics 100 and electronics / circuitry disposed on the back side of the i-PCB 10, and / or between the single-ended feedthroughs 52 electrically interconnecting the i-PCB 10 and the SC-PCB 50 (see FIG. 3 ). The embodiment of FIG. 12 further includes an optional recess or hole 104 in the surface 12 of the i-PCB 10 that receives the electronic component 100. Other electronic component mounting arrangements, such as sockets for integrated circuits (ICs), are also / alternatively contemplated. Advantageously, the hollow conductive tapered protrusion 20 acts as a Faraday cage, shielding the internal electronic components 100 from RF interference. Placing the electronic device 100 inside the hollow conductive tapered protrusion 20 also provides a more compact design (e.g., providing a sufficient footprint to potentially eliminate the need for the second PCB 50 shown in FIG. 3).

[0063] Referring to FIG. 13 , in another illustrative RF aperture embodiment, a radio frequency (RF) transparent material 110 covers the sensor element / pyramid (i.e., the conductive tapered protrusion 20 of other embodiments described herein). The RF transparent material 110 serves as a support / fixture to contain / hold a plate 112 of the DSA element / pyramid captured within the cover. The plate 112 can be captured within the cover 110 using or with the aid of an adhesive 114. In some embodiments, a circuit board can be configured to be attached to the plate (e.g., an i-PCB 10). The circuit board can receive the feet or base of the plate, and the plate can optionally be electrically attached (e.g., soldered) to the circuit board. In an alternative embodiment, the conductive plate 112 can be formed from a printed circuit board. As described above, the printed circuit boards that together form the conductive plate can create or include an air gap (e.g., air gap 92 in the embodiment of FIGS. 11 and 12 ). In some embodiments, the DSA's electronic components 110 (see FIGS. 11 and 12) or sensor elements / pyramids can be housed within the air gap and combined, for example, in a differential mode. Alternatively, the electronic components can be attached to the DSA board via screws 116 or holes 118, and the sensor elements / pyramids directly to each other or one another. In some embodiments, the RF-transparent material cover 110 includes an optional filler 120 filled with a variable dielectric.

[0064] Referring to FIGS. 14-17, a DSA (e.g., an expandable modular substrate) can include multiple sensor elements / pyramids 20 formed from a conductive plate. FIG. 14 shows a top view of an embodiment in which the conductive tapered protrusions 20 are equal in size and distributed across the i-PCB 10 in a linear array. FIGS. 15 and 16 show top and side views, respectively, of an embodiment in which the conductive tapered protrusions 20 are equal in size and distributed across the i-PCB 10 in a linear array, with smaller, sized conductive tapered protrusions 20s interspersed in the spaces between the linear arrays. FIG. 17 shows an embodiment in which the conductive tapered protrusions 20 are equal in size but distributed across the i-PCB 10 as other than a linear array, e.g., with unequal spacing between neighboring conductive tapered protrusions 20. The sensor elements / pyramids 20, 20s can be formed on the i-PCB 10, for example, as an array, and function as a radiating interface. In some embodiments, the signal capture areas of the sensor elements / pyramids 20 can be uniformly distributed across the area of ​​the array or radiating interface. This can be accomplished, for example, by positioning the center points of the sensor elements / pyramids 20 at equal distances from one another ( FIG. 14 ). In an alternative embodiment shown in FIGS. 15 and 16 , the center points of a first set of sensor elements / pyramids 20 with a first height H1 ( FIG. 16 ) can be positioned at equal distances from one another to uniformly distribute the signal capture area across the area of ​​the array or radiating interface, and a second set of sensor elements / pyramids 20s with varying second (or even different) heights H2, H3 can be randomly positioned or positioned to achieve the desired propagation or signal capture within the signal capture area defined by the first set of sensor elements / pyramids 20. In other words, the second set of sensor elements / pyramids 20s need not be uniformly spaced from one another. 17, the (first) set 20 of sensor elements / pyramids with a first height H1 can be positioned at random distances relative to one another to achieve a desired propagation or signal capture. The (first) set 20 of sensor elements / pyramids with a first height H1 can also be positioned to achieve a desired signal capture area.In an alternative embodiment (not shown), a first set of sensor elements / pyramids can include a first height H1 that varies to achieve a desired propagation or signal capture within the signal capture area. The first set of sensor elements / pyramids, random or organized to achieve a desired propagation or signal capture within the signal capture area, can also be interspersed with a second set of sensor elements / pyramids, as shown in Figures 15 and 16.

[0065] Referring to FIGS. 18-20 , in some embodiments, a DSA (e.g., a scalable modular substrate) can include multiple sensor elements / pyramids 20 formed from conductive plates (or otherwise formed, e.g., using a metal coating on dielectric protrusions as described in other embodiments herein). In some embodiments, the multiple sensor elements / pyramids 20 are each formed from a single plate that is wrapped around to create a cone-shaped sensor element / pyramid, and the multiple conductive plates can be configured to form an air gap ( FIGS. 18 and 20 ) or formed to be solid ( FIG. 19 ). As described above, in alternative embodiments, the electronic components of the DSA or sensor elements / pyramids can be housed within the air gaps of FIGS. 18 and 20 and combined, for example, in a differential mode. Alternatively, the electronic components can be attached directly to the DSA substrate, and the sensor elements / pyramids can be attached directly to each other or to one another. In some embodiments shown in FIGS. 18-20 , a dielectric material can be otherwise configured to surround or form the sensor elements / pyramids 20 of the DSA. In other words, the dielectric material can fill the gaps created between the sensor elements / pyramids. The dielectric material can form distinct layers, as in the embodiment of Figures 18-20. The layers can be formed from different materials, each with a different dielectric constant value. Alternatively, the layers can be formed from the same material, and the dielectric constant of a single material can be varied. For example, as shown in Figure 20, air holes or other dielectric voids can be formed within the dielectric material (e.g., the air space can be subdivided). The density of the air holes or other dielectric voids determines the overall dielectric constant. In one embodiment shown in Figure 20, many air holes or other dielectric voids are formed within the top layer of the dielectric material, which results in more of a match to the free space in the dielectric material within the top layer. The second top layer has reduced air holes or other dielectric voids, which reduces the ratio of air holes or dielectric voids to dielectric material. Through each layer of dielectric material, the ratio of air holes or dielectric voids to dielectric material is reduced (i.e., a dielectric lens effect).The ratio of dielectric material to air holes or dielectric gaps can be selected based on the desired propagation of RF signals through the dielectric material sandwiched between the sensor elements / pyramids of the DSA. As the signal or wavelength strikes the dielectric material, the propagation changes. In other words, the wavelength of the input signal is shortened. For example, when measuring a voltage difference, if or when the wavelength is shortened, there is an increase in the voltage difference.

[0066] Referring to FIGS. 21-23 , in some embodiments, the dielectric material can be otherwise configured to surround or form the sensor elements / pyramids 20 of the DSA. In other words, the dielectric material can fill gaps created between the sensor elements / pyramids. In the exemplary embodiments of FIGS. 21-23 , the dielectric material is formed from a single material or multiple materials that together form a refractive index profile (e.g., “uninterrupted”). In other words, a graded-index dielectric material is present. As shown in FIG. 23 , air holes or other dielectric voids can be formed within the graded-index dielectric material. The density of the air holes or other dielectric voids for the graded-index dielectric material can vary based on, for example, the desired signal propagation through the graded-index dielectric material.

[0067] Referring to FIG. 24, a close-up view of the graded dielectric of the embodiment of FIG. 23 is shown, along with additional explanatory notations. As shown in FIG. 24, the volume fraction of the air pores or other dielectric voids and the dielectric material results in an overall permittivity. By changing the permeability of the graded dielectric material or the permittivity of the graded dielectric material filled between the voids of the DSA sensor elements / pyramids 20, propagation changes as the signal or wavelength fills the graded dielectric material. For example, as shown in FIG. 24, a signal may propagate within a first dielectric. In the top portion of the graded dielectric material, the volume fraction of the dielectric material and the air pores or other dielectric voids have the same permittivity (e.g., based on the volume fraction of the material with openings). As the number or volume of the air pores or other dielectric voids relative to the dielectric material decreases, the permittivity also decreases. Each dielectric has a real portion and a complex portion. The complex portion has a loss tangent, which is also the dissipation factor. This causes attenuation. The goal is to limit attenuation by minimizing complexities on the dielectric material, which is how the dielectric material or composite is selected.

[0068] In some embodiments, the sensor elements / pyramids of the DSA can include a conductive plate formed from a dielectric material and configured to support the dielectric material. Holes or other dielectric voids can be formed in the dielectric material supported by the conductive plate. The holes or other dielectric voids can be used to vary the effective dielectric constant. The resistivity determines the amount of loss.

[0069] Although Figures 18-24 show the dielectric material terminating before the apex of the DSA sensor element / pyramid 20, the dielectric material may extend beyond the apex of the DSA sensor element / pyramid and / or completely encapsulate the DSA sensor element / pyramid.

[0070] In some embodiments, the RF aperture (e.g., DSA) is a modular plate: multiple DSAs can be selectively grouped together to form larger DSAs.

[0071] In further variants, DSA can be acoustic or magnetic. Magnetic DSA would allow for efficient magnetic field capture at frequencies as low as tens of hertz, potentially minimizing propagation. Acoustic DSA would allow DSA to be deployed on submarines and operate in the presence of water.

[0072] Referring to FIG. 25 , a DSA (e.g., an expandable modular substrate) can include multiple sensor elements / pyramids 20 formed from a conductive plate (or otherwise formed as described in various embodiments herein). In one embodiment, the base 10 of the DSA can be formed from a printed circuit board (e.g., an i-PCB as described) configured to support the sensor elements / pyramids 20. The circuit board can include multiple openings into which the baluns (i.e., the sensor elements / pyramids 20) are loaded. The circuit board with the openings creates a form factor that can be slidably received, for example, on a 3D-printed form factor (e.g., a block, etc.). In other words, the circuit board, together with the baluns, can form a “smart substrate” configured to store the intelligence of the DSA (e.g., using processing node 900 (see FIG. 28 )). The smart substrate can be, for example, injection molded. This smart substrate can be slidably received on any form factor. The smart substrate can be efficiently manufactured.

[0073] As shown in FIG. 26 , a DSA (e.g., an expandable modular substrate) can include multiple sensor elements / pyramids 20 formed from a conductive plate (or otherwise formed as described in various embodiments herein). While the previous embodiments employed a flat i-PCB 10, in the embodiment of FIG. 26 , the DSA is dome-shaped (or, more generally, has a non-flat or curved surface 130, e.g., in some more specific embodiments, with a fixed radius of curvature). The dome-shaped DSA of FIG. 26 (including sensor elements / pyramids 20 formed along the curved surface 130) can support beamforming and beamsteering. For example, the DSA can be configured to be attached to a curved surface, such as the exterior of an airplane. Using beamforming, a series of amplitudes can be applied to the sensor elements / pyramids 20 of the DSA to dissipate side loads and generate a focused, directional beam that can be directionally steered by the DSA. In other words, the amplitudes of the different elements are varied and the phase shift between adjacent elements can be used to direct the focused beam to the sensor elements / pyramids 20 of the DSA. The exemplary DSA of Figure 26 also includes an optional dielectric material 132 disposed between the sensor elements / pyramids 20, for example, as described with reference to Figures 18-24.

[0074] Referring to FIG. 27, a network 200 is shown that includes an access node 208 (e.g., a signal source / node for detecting signals, etc.) that communicates directly with one DSA 206, and a relay node 204 (e.g., which may be an interference node, e.g., used to relay signal information, etc.) that communicates with another DSA 202 (e.g., an expandable modular substrate, e.g., formed as an array and including multiple elements that may function as an electromagnetic radiation interface or other conductive material).

[0075] 28 shows a diagrammatic representation of a processing node 900 including a communications interface 902, a user interface 904, and a processing system 906 with storage 908 that stores software 910. Processing node 900 may be used, for example, in conjunction with the DSA of FIG.

[0076] Some further possible optional aspects and / or extensions are listed as follows: Antennas including a single port; Cable transmission lines or transmission lines not formed as an integral part of the sensor element; Inner conductors and / or dielectric materials formed with conductive tapered protrusions and / or sensors without plates (e.g., sensors formed as part of a bristle body structure); Conductive tapered protrusions formed from something other than metal or from multiple antennas; Transmission lines corresponding to multiple conductive tapered protrusions or antennas; Random signal capture area; Conductive tapered protrusions with lengths shorter than the wavelength; Not terminating the endoplasmic reticle in a resistive element that matches the impedance of the endoplasmic reticle (e.g., finding another way to "electrically blackout" the signal); Not digitally converting the signal to create a digital replica of the incident electromagnetic energy; Not creating an active surface using an electronic module to control the amplitude of the reflected signal (e.g., amplifying the signal by a factor related to actual scale); Pixel partition elements (conductive tapered protrusions) that do not correspond to a single horizontal / vertical circuit board. Use something other than RF waves (e.g., acoustic or magnetic apertures designed equivalently to the RF aperture embodiments described herein). Provide partition elements each having a frequency-dependent effective area. Form a circuit board as part of the partition element. In other words, form a partition element of a material that holds or supports a circuit board. A partition element is also considered a circuit board. A printed partition element includes a printed circuit board formed as part of it. A printed circuit board on or formed with the partition element is used to guide and / or distribute RF signals on the remainder of the partition element, etc. In some possible embodiments, the circuit board terminates in a balanced transmission line. A support substrate (e.g., the illustrative i-PCB 10) can alternatively be formed as part of the conductive tapered protrusion or partition element. A conductive "seat" or "pad" not located on the substrate or surrounding the conductive tapered protrusion or partition element.This refers to a "conductive" seat or pad, such as copper. A non-conductive seat or pad may use a material that provides an acoustic response, such as a polymer (in the case of an acoustic aperture). Similarly, different properties may also be provided to transduce RF waves.

[0077] Below, some further illustrative implementations of conductive tapered protrusions are described. In some embodiments, these are solid elements, as in the examples below.

[0078] The protrusion should mount securely to the surface (flat or curved) and make discrete electrical contact along each side of the protrusion. The protrusion may be a non-rounded protrusion with at least three faces and three sides connecting the faces. Excessive "play" or uncoupled movement between the interface substrate and the protrusion can result in degraded RF performance.

[0079] 29-31 , one embodiment employs a conductive tapered protrusion 300 and an interface substrate 302 containing conductive traces 304. The protrusion 300 is fabricated from a solid conductive material, such as copper or aluminum metal bar stock, which is readily available, high-performance, and cost-effective. An illustrative conductive tapered protrusion 300 has a square pyramid shape. The protrusion 300 is held against the substrate 302 using screws or other threaded fasteners 306, which create consistent pressure along the base edge. This pressure ensures electrical contact because the conductive traces 304 are slightly higher than the non-conductive elements of the circuit board 302, exposing the conductive traces 304, as seen in FIG. 29 . A top view of the configuration with the mounted protrusion 300 is shown in FIG. 30 , while FIG. 31 shows a top view of the interface substrate 302 alone. In this design, protrusion 300 has at least one small protrusion (two small protrusions 308 in the illustrative embodiment) that maintains the proper orientation of protrusion 300 relative to the conductive surface. Protrusion 300 has an alignment hole 310 that is threaded to receive screw 306 after the screw passes through a through hole 312 in interface substrate 302. This mounting method is independent of the length of protrusion 300, so the height of protrusion 300 above the surface of substrate 302 is an open design parameter.

[0080] Referring to Figures 32-35, an embodiment is shown that allows for mounting of the protrusion to cooperate with a non-PCB interface board (i.e., an interface board that does not include printed circuitry). The mounting method uses a sheet commodity to electrically connect the pyramid to a vertical board (not shown in Figures 32-36) below the interface board. Figures 32 and 33 show isolated side and bottom views, respectively, of a suitable conductive tapered protrusion 300, which may be of the same design as in Figures 29-31, e.g., having a square pyramid shape. Here, the protrusion 300 rests on a conductive (e.g., metal) mounting portion 320. The mounting portion 320 is shown alone in Figure 34, with the protrusion 308 captured within the hole 322 of the mounting portion 320. The mounting portion's tab 324 (labeled in Figure 34) is then inserted and protrudes through the interface board 330, as shown in the exploded perspective view of Figure 35. Screws 306 then advance from the backside of the interface substrate 330 through the individual mounting portions 320 and into the alignment holes 310 of the individual protrusions 300. Again, mounting portions can be used with protrusions 300 of different heights. In this configuration, the mounting portions 320 can be designed so that the base size is interchangeable as well. As long as the tabs 324 mounted through the interface substrate 330 remain in the same location, the size of the mounting portions can be freely changed. As shown in FIG. 35 , this design allows the interface substrate 330 to be a non-conductive housing that can contain electrical circuitry for operating the array of conductive tapered protrusions 300 in RF transmit and / or receive modes.

[0081] Referring to FIG. 36, another embodiment employs a conductive tapered protrusion 340 in which the protrusions 308 of the embodiment of FIGS. 29-35 are replaced by recesses 348. In this embodiment, the interface substrate 330 of the embodiment of FIGS. 29-35 is replaced by an interface substrate 350 including protrusions 352 that mate with the recesses 348. In other words, the convex protrusions 308 are replaced with holes 348, which, in some manufacturing processes, reduces machining time and therefore costs and results in less material waste. To do so, the interface substrate 350 is designed to provide the protrusions 352 itself. The interface substrate 350 may be, for example, injection molded or produced by additive manufacturing; in both cases, the inclusion of the protrusions 352 incurs little material or molding cost. For the same strength as the metal protrusion 308 on the solid metal protrusion 300, the protrusion 352 on the non-metallic interface substrate 350 should be larger due to its material composition, but this is not detrimental as the increased hole size of the mounting portion 320 and protrusion 340 does not affect cost or performance.

[0082] In the modified approach, the use of the lug is eliminated by using a second screw with both screws offset from the center of the lug to which it is fastened. The use of two screws requires two tapping steps, doubling the number of screws and doubling the time required for fastening.

[0083] Referring to Figures 37-39, in some designs, the conductive tapered protrusion is faceted with various geometric shapes. As mentioned, the conductive tapered protrusion 300 shown in Figures 30 and 35 is a square pyramid with four-fold rotational symmetry. Figure 37 shows an embodiment that is also a square pyramid, but with only two-fold rotational symmetry. This design can support different susceptibility and signal chain complexity along opposing orthogonal polarizations. Figure 38 shows an embodiment in which the conductive tapered protrusion is a six-sided (i.e., hexagonal) pyramid with six-fold rotational symmetry. The hexagonal structure provides three different polarizations. This is useful when precise measurement or transmission of polarizations is required, or when a larger number of signal chains per surface area is required, thus increasing transmission power and reducing noise for the same area. Figure 39 shows an embodiment in which the conductive tapered protrusion is a three-sided (i.e., tri-) pyramid with three-fold rotational symmetry. These have properties similar to the hexagonal design of Figure 38. More generally, any configuration in which a geometry can be tessellated is considered a possibility, the simplest being a geometry that can be tessellated by itself.

[0084] Below, some further illustrative implementations of conductive tapered protrusions are described, in which the protrusions are solid elements, for example formed by plates, as in the following examples.

[0085] Fabricating a solid conductive tapered protrusion uses a substantial amount of internal material that does not affect RF performance because electromotive forces flow on the outer surface of the protrusion only to a depth equal to the skin depth of the specific frequency of the coupled RF radiation. Employing a hollow conductive tapered protrusion can reduce weight, material costs, and processing costs. The hollow protrusion can be fabricated from sheet goods such as a conductive plate. In various embodiments discussed next, the conductive plate may have a convex support, or may be a freestanding or self-supporting plate, or may have a concave support.

[0086] Key attributes for market acceptance of DSAs include size, weight, power, and cost per equivalent performance (SWAP-C). The use of faceted, conductive tapered protrusions (such as those in Figures 30, 35, and 37-39, as opposed to conical protrusions) facilitates machining the faceted protrusions from solid aluminum or copper stock. While convenient, significant material is used within the solid protrusion, and significant molding time increases both the cost and weight of the DSA. Because electromagnetic waves travel only a small depth into the protrusion (i.e., skin depth), only the first few micrometers of the outer surface need be conductive. The calculation for skin depth is as follows:

number

number

number

number

number

number

[0087] Referring to Figures 40 and 41, a conductive tapered protrusion 400 is milled from bar stock and then processed by a finishing step in which excess material is removed. Figure 40 shows an example of this approach, in which a single threaded hole 402 is maintained in the center of the structure, and the remaining material is milled away to maintain a thickness of material appropriate for mechanical rigidity. Figure 40 shows a central cylindrical support 404 positioned inside the hollow protrusion 400. The illustrative central cylindrical support 404 has a circular cross-section extending to the top of the protrusion; however, this cylindrical support could have a square or rectangular cross-section, which would be quicker to machine, with only a moderate weight penalty. While this solution reduces the weight of the protrusion, this increases molding time, and therefore cost, compared to a solid protrusion, while maintaining the same material cost as a solid protrusion.

[0088] The conductive tapered protrusion 400 can be manufactured by casting or additive manufacturing rather than subtractive milling. Casting reduces manufacturing costs and material waste and is only suitable for high-volume applications. Protrusions 400 manufactured by casting will likely have rough surfaces and will be thicker than necessary for mechanical rigidity. For additive manufacturing, the material must be conductive, limiting the applicable techniques. Generally, additive manufacturing is the most expensive, and milling is next most expensive and will result in rough surfaces.

[0089] Below, plate-based approaches for manufacturing conductive tapered protrusions are described. Three variants of the plate-based approach are described: a convex support approach, a freestanding or self-supporting approach, and an approach utilizing a concave support.

[0090] Referring to Figures 42-48, an embodiment employing a convex support is described. Here, individual conductive (e.g., metal) tapered plates 420 (shown alone in an alternative perspective view in Figure 42) are internally supported by a dielectric structure 422, shown in alternative perspective views in Figures 43 and 44. Each conductive tapered plate 420 has a tab 424 at its bottom, which electrically extends the plate beyond the base of the protrusion and makes an electrical connection to an interface board (PCB or non-PCB), a vertical board located below the interface board, or some other electronic device. Each plate 420 also has a bend 426 within the plate at the point where the protrusion terminates. The bend 426 allows the plate 420 to travel at a 90-degree angle through the interface board. While optional, this bend configuration conserves material and provides easier connections. A third feature is an angled extension 428 below the plane of the tapered protrusion. This angled extension 428 mates with the interface substrate, ensuring sliding and positive capture into the substrate. This also adds strength to the flexure 426.

[0091] Conductive tapered plates 420 are supported by a dielectric structure 422 shown in FIGS. 43 and 44. This structure has four tapered (e.g., "V"-shaped) receptacles 430 (for an illustrative four-sided faceted protrusion) into which four individual conductive tapered plates 420 mate. The mating is by the "V"-shaped (or more generally, tapered) receptacles 430 capturing the edges of the conductive "V"-shaped (or more generally, tapered) plates 420 and allowing the conductive tapered plates 420 to slide in as shown in the alternative perspective views of FIGS. 45 and 46. The conductive tapered plates 420 thus define the facets of the conductive tapered protrusion 400. As seen in Figures 44 and 46, the bottom of the dielectric structure 422 has two protrusions 432 to prevent rotation once mounted on the interface substrate 440 (shown alone in Figure 47) with matching locating holes 442. Additionally, in the center there is a hole 444 that can be threaded to receive a screw or smoothed for a rivet. Fasteners used in this hole run from the back of the interface substrate into the support structure and hold the entire assembly rigidly together. Once assembled, the system has the appearance of Figure 48, showing five conductive tapered protrusions 420, 422 mounted on the top side, and Figure 49, showing the back side with protruding tabs 424.

[0092] Benefits of this plate-based approach include its interchangeability with solid protrusion designs, allowing the choice of solid or plate-based protrusion type to be made on an application-by-application basis. Additionally, the plate design configuration is lighter and has significantly lower material costs than solid or hollowed protrusion approaches. The dielectric support 422 can be formed by an injection molding process for larger manufacturing volumes or via additive manufacturing in smaller manufacturing volumes. Assembly time is slightly increased due to the step of inserting the plate into the support structure. One RF performance benefit is that the electrically insulating plate can provide higher cross-polarization isolation compared to solid or hollowed protrusions, where a conductive path exists between the facets.

[0093] In the previous examples, internal structures (i.e., dielectric supports 422) were required to support plate 420. However, experiments have shown that complete isolation of the individual sides of the faceted conductive tapered protrusions leads to mechanical resonances that can degrade RF performance. To address these challenges, several illustrative configurations for providing free-standing protrusions that do not require internal structures are disclosed below. These conductive tapered protrusions are fabricated using sheet goods, further reducing costs. Any of the examples can be attached at full-length edges or at points through the application of solder or by creating tabbed connections in which a tab located on one side slides into a cutout on an adjacent space. A point-based soldering solution may be ideal in that it eliminates mechanical resonances by rigidly attaching the surfaces while still allowing a significant amount of cross-polarization isolation.

[0094] Some illustrative examples that follow show protrusions that reach a point for simplicity, however, reaching a point is not necessary and for mechanical strength or ease of processing, the top of the protrusion can be molded smaller in size so that it matches the bottom of the protrusion.

[0095] An example is shown in Figures 50 and 51. In this example, Figure 51 shows a faceted conductive tapered protrusion 450 formed by bending a single-piece cutout 452 from a metal sheet, as shown in Figure 50. As shown in most detail in Figure 50 prior to the bending step, the cutout 452 includes (in this example) four facets 454 that abut at a small square apex facet 456 (or alternatively, at the apex as seen in the alternative embodiment of Figures 52-54). The facets 454 of the single-piece cutout 452 are bent at their junctions with the apex facet 456 (or apex) to form the faceted conductive tapered protrusion 450. Each facet 454 includes a tab 458 distal from its junction with the apex facet 456 (or apex), which mates into an interface substrate 460 and electrically connects with the RF circuitry, as seen in Figure 51. In the assembled projection 450 of Figure 51, the edges of adjacent facets 454 may optionally be connected by soldering or mating tabs (features not shown in Figures 50 and 51). As just described, the apex facet 456 is optional but can provide added mechanical strength (if the apex facet 456 is omitted, the four facets will meet at the apex).

[0096] Referring to FIG. 52 , an alternative embodiment is shown with a faceted, conductive, tapered protrusion 470 shown in the lower portion of FIG. 52 and a corresponding single-piece cutout 472 shown in the upper portion of FIG. 52 . This embodiment omits the apex facet 456 of the embodiment of FIGS. 50 and 51 , so that the four facets 474 of this embodiment reach a point. In addition, the tabs 458 of the embodiment of FIGS. 50 and 51 are omitted, and at their location, a bottom plate 476 is attached to one of the facets 474 within the cutout. The bottom plate 476 has an opening 477 for capturing a fastener 478, such as a bolt head or rivet. If a bolt is used, the attachment is performed before the bend is complete, since the inside of the protrusion 470 will not be accessible once the bend is complete. Once bent, the protrusion 470 can be soldered at certain points or along the entire edge, or a tabbed connection can be used (feature not shown). Alternatively, the bottom edge of facet 474 can be soldered to the interface substrate, or the bottom can be folded to create a tab that rests on the interface substrate. This variation is lightweight. It can provide good cross-polarization isolation. However, the nature of the fold can result in variability in RF performance because there is no mechanical connection. Additionally, as shown in FIG. 52 with a single screw, the pyramid can rotate if only an interference fit is used to electrically attach the faces. Fastening the bottom plate 476 with two screws would double the number of attachment steps but eliminate the rotation issue. In this embodiment, a PCB is suitably used for the interface substrate to provide electrical connection to protrusion 470. Further variations are possible, such as providing a bottom plate on more than one of facets 474, so that when folded, the bottom is duplicated, thus adding rigidity and consistency at the expense of material weight and cost.

[0097] Referring to FIG. 53 , another illustrative faceted conductive tapered protrusion 480 is shown in the lower portion of FIG. 53 , and a corresponding single-piece cutout 482 is shown in the upper portion of FIG. 53 . This embodiment is similar to that of FIGS. 50 and 51 and includes four facets 454 with a tab 458, but the apex facet 456 is omitted so that the four (side) facets reach a point. Note also that further variations are contemplated, such as replacing the apex facet 456 of the embodiment of FIGS. 50 and 51 with a rounded apex, for example, formed by a retraction action. With respect to the tab 458 of the embodiment of FIGS. 50 and 51 and 53 , the tab 458 is bent so that the protrusion 480 abuts the interface substrate 460 at a 90-degree angle when bent into its final shape (e.g., as at the bottom of FIGS. 51 and 53 ). The tabs 458 can be soldered to electrical traces on the interface substrate 460 when the interface substrate 460 is a printed circuit board (PCB). This allows for a strong mechanical and electrical connection of the conductive tapered protrusions 450, 480 to the interface substrate 460. Alternatively, the tabs 458 can pass through the interface substrate and be attached to the vertical substrate below. Optionally, the adjacent edges of the facets 454 can be joined using soldering or a tab and receiver arrangement (not shown). This method improves on the flat-bottom version in that it reduces weight and requires no mechanical connection other than joining the tabs to the PCB. The use of the tabs 458 reduces assembly time and overall system size, weight, and cost (SWAP-C) compared to an approach using a bottom plate 476 such as in the embodiment of FIG. 52.

[0098] 54, another illustrative faceted conductive tapered protrusion 490 is shown in the bottom portion of FIG. 53, and a corresponding single-piece cutout 492 is shown in the top portion of FIG. 53. This embodiment employs four facets 494, each with a tab 498 positioned offset at the corner of the facet 494. Here, the interface substrate 460 has a thickness at least the depth of the triangular facet 494 added to the tab. While the illustrative tab 498 is offset to one side, it could alternatively be in the center, with triangles added to both sides.

[0099] Referring to FIG. 55 , an embodiment employing a plate with a concave (i.e., external) support is disclosed. The DSA may include a radome (i.e., a structural enclosure, which may optionally be weatherproof) to protect the conductive tapered protrusions and provide a safe surface for external contact. In this embodiment, the radome 500 includes or defines a form 502 with tapered-protrusion-shaped recesses 504. To construct the conductive tapered protrusions 506, a sheet of metal is laid over the form 502 (e.g., at the location indicated diagrammatically by dashed lines 508 in FIG. 55 ), and then a stamping is applied to force the sheet metal into the tapered-protrusion-shaped recesses 504. Alternatively, a separate sheet may be stamped to form each protrusion 506. The stamping may be shaped within the same cross section as the protrusions 506. (Note that in schematic diagram 55, a gap is shown between the surfaces of tapered-protrusion-shaped recess 504 and protrusion 506 to distinguish them; however, in actual fabrication, tapered protrusion 506 would be pressed against and in contact with the corresponding surface of tapered-protrusion-shaped recess 504.) This approach has certain benefits. It facilitates automation of DSA assembly. It also provides support for protrusion 506, thereby allowing for thinner materials and a higher level of environmental robustness. Radome 500 should be made from a dielectric material such as plastic and can be fabricated by manufacturing approaches such as injection molding or three-dimensional (3D) printing techniques. Injection molding can construct a strong, lightweight, and low-cost radome. Note that form 502 need not be solid; instead, it can be largely hollow.

[0100] Below, several further illustrative implementations are described that address the problem recognized herein that if the interface substrate is metal (e.g., a PCB with a ground plane), it may adversely affect the RF performance of the DSA.

[0101] The DSA architecture works best without conductive material directly behind the gaps between the conductive tapered protrusions. On the other hand, most radio frequency components perform best when mounted in close proximity on a ground plane, e.g., a PCB with a ground plane. To address this issue, some embodiments disclosed herein employ a PCB that is mounted perpendicular to the surface on which the protrusions are mounted.

[0102] In a DSA design such as that of FIG. 2, the protrusion 20 is mounted directly to a printed circuit board (PCB) 10, with the opposing side of the PCB 10 used to mount an RF component (e.g., chip balun 30 in the embodiment of FIG. 2). The PCB 10 has at least two layers with conductive traces connecting the "top" protrusion 20 to the balun 30, and either the inner layer (when there are more than two layers) or the outer layer as a flooded ground plane. The flooded ground plane provides a low-resistance surface for electricity to flow through by filling the surface to the maximum extent possible with conductive material. The ground plane is included to improve RF component performance.

[0103] Referring to Figure 56, this is illustrated diagrammatically by showing conductive tapered protrusions 20 and an underlying ground plane 510 (which is part of PCB 10 in the embodiment of Figure 2). Ground plane 510, which is integral with the same substrate (i.e., PCB 10) on which protrusions 20 are mounted, provides a conductive surface mounted less than one full wavelength away from the gaps between protrusions 20 at their bases. Figure 56 diagrammatically shows the resulting RF interference due to reflection of incident radio frequency waves back into the protrusion space. While interference can be both constructive or destructive, the overall result is a degradation of wideband performance and increased design complexity required to resolve such interference at multiple angles of arrival and frequencies.

[0104] One solution (not shown) is to replace the continuous ground plane with one that extends under the base of the protrusions but not between them. With such an approach, the RF components would be miniaturized sufficiently so that they fit completely under the base of the protrusions. However, this approach would require a complex "grid-like" ground plane and very miniaturized RF components.

[0105] Referring to FIG. 57, another solution is illustrated. By further moving the conductive surface, i.e., ground plane 510, one wavelength away from the base of the protrusion 20, the PCB can then be used in a perpendicular orientation to the impinging electromagnetic wave (e.g., as in FIG. 2). This approach involves providing standoffs 520 from the protrusion 20 to the PCB, which provide rigid support, and conductive connections 522 per face of the protrusion 20—e.g., four connections 522 when the protrusion 20 is square or rectangular. In an alternative embodiment (not shown), the conductive connections 522 provide rigid support so that the separate standoffs 522 can be optionally eliminated. The standoffs provide spacing 524 between the base of the protrusion 20 and the ground plane 510. This approach is most suitable for higher RF operating frequencies, as at low frequencies the required spacing 524 becomes large, which reduces stiffness and can lead to failure under shock and vibration. For example, at 400 MHz, the spacing 524 provided by the standoffs would need to be approximately 0.75 meters. In contrast, at 10 GHz, the spacing 524 provided by the standoffs would only need to be 3 centimeters.

[0106] Referring to FIG. 58, another solution is to mount conductive tapered protrusions 20 on a non-conductive interface substrate 550 and mount RF components 552 on vertical printed circuit boards (PCBs) 560 oriented perpendicular to the interface substrate 550. That is, rather than mounting the protrusions 20 on an interface substrate that is a PCB with a conductive ground plane, the embodiment of FIG. 58 uses a dielectric substrate interface substrate 550. The top surface of the dielectric interface substrate 550 supports the protrusions 20, and a set of PCBs 560 for supporting the RF components 552 are oriented perpendicular to the surface 550. The vertical PCBs 560 contain or support the RF components 552, which are mounted across the ground planes of the PCBs 560. In one embodiment (shown in FIG. 58), there is a vertical PCB 560 located between each row of protrusions 20. In another embodiment (not shown), there is one vertical PCB underlying each row of protrusions. The placement of the vertical PCB 560 between the rows of protrusions 20 is highly suitable for operating the DSA in differential mode.

[0107] The interface substrate 550 can be fabricated from any rigid or semi-rigid dielectric material, such as plastic (e.g., acrylonitrile butadiene styrene, or ABS). Alternatively, the interface substrate 550 can be a printed circuit board (PCB) but without a continuous ground plane. Using a PCB with conductive traces but without a ground plane as the interface substrate 550 allows for easier connection of signals between the protrusions 20 to the vertical PCB 560 (which also has no ground plane). In one approach, the connection to the vertical PCB 560 employs a card edge connector. Using a PCB without a ground plane as the interface substrate 550 also allows the edge to be terminated with loads directly on the PCB, simplifying the design. However, utilizing a PCB without a ground plane as the interface substrate 550 increases costs over using a sheet of dielectric material. The sheet dielectric can be fabricated to capture the vertical PCB via various fastening configurations, such as screw holes, with corresponding right-angle brackets, edge connectors, tenons, etc. Another option is to create a mount for the protrusion 20 to which it is attached, a mount through screws, rivets, or the like, and a surface, and a mount that is mechanically and electrically attached to the vertical PCB 560. The mount may be soldered or compression-typed, optionally assisted by screws.

[0108] In some embodiments, the interface board 550 forms part of the housing for the DSA; for example, the interface board 550 can be one side of a five-sided box enclosure housing. The top side carries the protrusions and optional radome, while the bottom side has connection points for an optional back cover (see FIGS. 64 and 65).

[0109] In some embodiments, the edge 560 of the vertical PCB is affixed to the interface substrate 550. In this arrangement, the vertical substrate 560 is subjected to stresses when under shock or vibration. These stresses can be mitigated by rigidly mounting the interface substrate 550 and / or by the inclusion of a second support substrate 562 oriented parallel to the interface substrate 550 so as to affix the edge of the vertical substrate 560 distally from the interface substrate 550, as shown in FIG. 59 . The second support substrate 562 should also not contain a ground plane unless the vertical substrate 560 is of sufficient size to position the second support substrate 562 more than one RF wavelength away from the base of the protrusion 20.

[0110] FIG. 60 shows a plan view of a DSA incorporating the concepts described in FIG. 58. Here, the upper surface of the interface substrate 550 is a PCB (without a ground plane) that allows interconnection 564 of vertical row substrates 560 to the columns of protrusions 20 and optional edge terminations 566. The design of FIG. 60 can also optionally include a second support substrate 562 (obscured from the view of FIG. 60), which may improve the mechanical rigidity of the assembly to improve robustness to shock and vibration. If a second support substrate 562 is included, it can optionally include additional routing of electrical connections between the vertical row substrates 560, simplifying connection to further signal chain elements. As mentioned above, if the vertical substrate 560 is of sufficient size to position the second support substrate 562 more than one RF wavelength away from the base of the protrusions 20, the second support substrate 562 may also include a ground plane and RF components.

[0111] 61-63, in another embodiment, two orthogonal sets of vertical substrates 560, 570 are provided. One set of vertical substrates 560 (also referred to as "row substrates") is perpendicular to the interface substrate 550, while another set of vertical substrates 570 (also referred to as "column substrates") is perpendicular to the interface substrate 550 and also perpendicular to the row substrates 560. In this embodiment, the row substrates 560 and the column substrates 570 include cutouts 572, allowing the row and column substrates 560, 570 to interdigitate together and form a two-dimensional grid of vertical substrates 560, 570, all of which are perpendicular to the interface substrate 550. This facilitates providing electrical connections to both the rows and columns of protrusions 20, and the grid of interdigitated row and column substrates 560, 570 provides additional rigidity to the assembly. The cutouts 572 allow the intersecting row and column PCBs 560, 570 to intersect and interdigitate with each other. If the cutouts 572 are mechanically affixed (e.g., by adhesive) or have an interference fit when assembled, the assembly becomes a free-standing two-dimensional grid. Although not shown in Figures 61-63, the second support substrate 562 of the embodiment of Figure 59 can also be included to further improve rigidity. Benefits of this method using intersecting row and column vertical substrates 560, 570 include it simplifies electrical connections to both the rows and columns of protrusions 20, improves assembly rigidity, and optionally allows for the omission of the second support substrate 562 (due to the improved rigidity provided by the interdigitating row and column substrates 560, 570). Again, the interface substrate 550 can be made of any non-conductive material or can be a PCB without flood fill (i.e., without an integral ground plane). However, the use of both column and row substrates 560, 570 may alleviate the need for conductors on the interface substrate 550, thus allowing the interface substrate 550 to be a simple dielectric substrate without printed circuitry.

[0112] Referring to Figures 64 and 65, a complete DSA assembly is shown, including the embodiment of Figures 61-63. Figure 64 shows an exploded perspective view of the DSA assembly. This embodiment does not include the second support substrate 562. In the DSA assembly of Figure 64, the interface substrate 550 is a surface of a five-sided housing or enclosure 580, shown alone in Figure 65. The protrusions 20 are positioned on individual mounts 320 (mounts 320 were previously shown in and described with reference to Figure 34), which are secured by screws 306 (as shown in and described with reference to Figure 36). The DSA assembly of Figure 64 further includes a radome 582 with an associated gasket 584. The radome 582 fits over the conductive tapered protrusions 20 and over some or all of the enclosure or housing 580, and is secured by fasteners 586. The backside of the enclosure or housing 580 is provided with a rear cover or support 588 and associated gasket 590, which are secured to the DSA assembly by fasteners 592. The design utilizes the interface substrate 550 as a dielectric surface, also forming the surface of the five sized housings 580 (see also FIG. 65). The housings 580 contain grooves on their inner surfaces (not shown) that complement the edges of the vertical substrates 560, 570, thereby improving shock and vibration survivability. The interface substrate 550 (and optionally the entire housing 580) may be a single-piece plastic component, fabricated, for example, by additive manufacturing or injection molding. As described, the protrusions 20 connect to individual mounts 320, which are then mechanically and electrically attached to the row and column substrates 560, 570. The mounts 320 can be made from stamped metal, which significantly reduces the material and processing costs of the protrusions 20.

[0113] The DSA designs disclosed herein can be employed with a wide range of RF component configurations. Below, several example signal chains are presented that are suitable for use with the disclosed DSA.

[0114] DSAs interface with free space for electromagnetic capture and / or activation in different modes (depending on the application), which gradually reduces the RF signal difference between the two points. Most commercial off-the-shelf RF circuits exhibit a single-ended mode of operation, where the signal is on a single conductor and referenced to ground. DSA architectures can be made to work with single-ended circuits through a transformer called a balun (i.e., "balanced / unbalanced"). This is illustrated in FIG. 66, which shows a side view (top drawing) and a top view (bottom drawing). FIG. 66 shows the RF coupling, where a balun 600 connects conductive tapered protrusions 20 and converts the differential signal to a single-ended signal. FIG. 66 shows a 3×2 DSA configuration (which can extend to any M×N DSA configuration (M and N are each integers greater than or equal to 1)). In this case, the conductive tapered protrusions 20 are four-sided faceted pyramids, with each facet connected to the opposing facet of a neighboring protrusion 20 through differential sides of the balun 600. This space is referred to herein as a pixel.

[0115] Generally, the balun is connected to some form of signal chain, and two specific embodiments are shown in FIG. 67. The embodiment of FIG. 67 relates to a DSA that is a transceiver, i.e., provides both transmit (TX) and receive (RX) operations. If a transmitter-only, i.e., a DSA that provides only transmit (TX) operations, or a receiver-only, i.e., a DSA that provides only receive (RX) operations, is desired, the switch 614 (upper time-division duplexed signal chain 610) or the circulator or duplexer 616 (lower frequency-division duplexed or full duplexed signal chain 612) can be omitted, and the path (TX or RX) that is not needed can also be omitted. FIG. 67 also shows direct attachment of the signal chains 610, 612 to the balun 600, equalizing the one-to-one ratio between the number of protrusions 20 and the number of opposing sides of the signal chains.

[0116] The upper portion of FIG. 67 shows one embodiment of a signal chain 610 that uses an RX / TX switch 614. The design of the signal chain 610 does not directly power the receive circuitry with the transmit circuitry. The switch 614 serves the function of isolating the TX and RX paths; the circuit 610 cannot both transmit and receive simultaneously, often referred to as time-domain duplexing (TDD). However, the electrical architecture of a DSA may have some signal chains 610 operating in RX mode and some operating in TX mode, providing both transmit and receive operation simultaneously, albeit with reduced aperture efficiency. The use of a switch 614 in the signal chain 610 has the benefits that switches are low cost, readily available, can handle high power, and can operate over a wide bandwidth.

[0117] The lower portion of Figure 67 shows an embodiment of a signal chain 612 that can operate in either frequency division duplexing (FDD) or full duplexing (FD). FDD allows simultaneous transmission and reception by transmitting and receiving on separate frequencies and filtering out the transmit frequency from the received signal. Here, the switch 614 is replaced by a component 616, such as a diplexer or circulator. A diplexer splits transmit and receive by frequency, while a circulator acts like a series of gates, allowing transmit energy to avoid reflection primarily into the RX path. Diplexers are not tunable and require a built-in design approach for frequency operation (e.g., specified transmit and receive frequencies or frequency bands). Typical commercially available circulators do not exceed approximately 1 GHz (or one octave) in bandwidth. This places constraints on DSAs in using signal chains such as the illustrative signal chain 612. FD means that the signal chain can operate in both transmit and receive modes simultaneously on the same frequency while maintaining isolation of the RX path from the TX path. This is typically achieved through the use of different antennas or circulators combined with cancellation circuitry that connects the TX path to the RX path through reverse signals. The DSA architecture has the TX and RX paths on different sets of lobes 20, and therefore can achieve full duplex operation by using different signal chains for each mode or by including circulators.

[0118] In either TDD, FDD, or FD modes, the signal chain can be varied to support a number of different electrical architectures, each with their own SWAP-C / performance tradeoffs.

[0119] Referring to Figure 68, an illustrative 4x4 DSA supports up to 40 individual signal chains, which are represented diagrammatically in Figure 68 by circles 620. There are benefits to this approach, such as a lower noise floor due to the averaging uncorrelated noise of the low-power TX amplifier (often called a power amplifier, PA) and the RX amplifier (often called a low-noise amplifier, LNA), increased signal dynamic range, aperture subsetting, where part of the aperture is dedicated to one function and a different part to a different function, and the ability to use dynamic and arbitrary beamforming and polarization generation. However, in SWAP-C, this performance comes at a disadvantage because each signal chain consumes space and power and increases cost.

[0120] Referring to Figure 69, therefore, it is sometimes desirable to combine signals so that one signal chain supports multiple pixels. One way is to combine pixels into rows and columns, which maintains multiple polarization operations and beam steering and shaping in direction and elevation. To combine pixels, a combiner or splitter (e.g., combiner 632 or combiner 634 in the illustrative signal chain 630 of Figure 69) is inserted into the signal chain at one or more locations in the TX / RX path. Combiners 632, 634 are bidirectional devices, meaning that current can flow in either direction or in both directions simultaneously. Figure 69 shows that combiner 632 can be placed between the duplexer and the balun, or alternatively, combiner 634 can be placed upstream of a power amplifier (PA) 636 in the TX path and downstream of a low-noise amplifier (LNA) 638 in the RX path. (While FIG. 69 shows the combiner 632 coupled to a single illustrative pixel via the illustrated balun 600, more generally, the combiner 632 could be coupled to multiple pixels via the pixel's individual baluns. Similarly, the illustrative combiner 634 is coupled to a single illustrative pixel via the pixel's power amplifier 636 and low-noise amplifier 638, more generally, the combiner 634 could be coupled to multiple pixels via the pixel's individual components 634, 636.) The first location (i.e., combiner 632) is lower cost because one combiner 632 is used for both the TX and RX paths; however, this arrangement suffers a performance penalty because the combiner 632 typically has limited power handling capability and inserts signal reduction (loss) in the RX path. The second location (i.e., combiner 634) doubles the number of combiners required, but the thermal noise per pixel is uncorrelated and reduces the system noise.

number

[0121] The signal chains 630 in Figure 69 assume that there are a sufficient number of signal chains to perform beam steering and beam forming as desired. While some beam forming and steering can be performed using two signal chains, four signal chains provide a better performance solution. The most costly and most power consuming portion of the signal chain is often the analog-to-digital conversion and digital signal processing required to perform the operations needed for beam steering and forming.

[0122] Referring to Figure 70, a signal chain 640 illustrates one way to reduce system cost. The signal chain 640 includes a phase shifter or time delay 642 downstream of a digital-to-analog converter (DAC) 644 and a phase shifter or time delay 646 upstream to an analog-to-digital converter (ADC) 648. This method reduces the number of signal chains required; in some cases, only one signal chain is needed. The tradeoff is that the time shifters or delays 642, 646 may limit wideband operation in some implementations.

[0123] Note that in all signal chains shown herein, the digital-to-analog converter may optionally be followed by a mixer, which increases the frequency of the signal, and the analog-to-digital converter may optionally be preceded by a mixer, which decreases the frequency of the signal.

[0124] Referring to FIG. 71 , some RF components can operate differentially on the signal instead of single-ended. Using such “differential” RF components allows the DSA to operate with a fully differential signal chain 650 as shown in FIG. 71 , where the inputs are maintained as balanced pairs all the way to or from the digital word at the ADC 648 or DAC 644. The power amplifier (PA) 636 and low-noise amplifier (LNA) 638 process the differential signal in this embodiment. The illustrative embodiment of FIG. 71 further includes a switch (or, alternatively, a duplexer or circulator) 652 to provide time- or frequency-division duplexing of the TX and RX differential paths, as well as an optional filter 654 upstream of the LNA 638. Note that the switch, duplexer, or circulator may be coupled to one or more aperture pixels without an intervening balun.

[0125] A variant embodiment may employ a semi-differential signal chain (not shown) in which the differential signal is maintained short of the DAC and ADC and a balun is used to convert at that point.

[0126] Each combiner introduces loss, limits the number of channels, and increases SWAP-C. Various designs can be employed to mitigate these effects.

[0127] Referring to FIG. 72, an embodiment is shown in which a combiner 632 is included after signal chain 660 (e.g., this could be signal chain 630 in FIG. 69 or signal chain 640 in FIG. 70) and spans four pixels. These pixels are shown in a column, and combiner 632 is a 4-to-1 combiner utilized in front of signal chain 660. In this embodiment, all four pixels receive the same signal, and pixel-level steering along the axis is not possible. An optional modification is to place a phase shifter between the combiner and the balun. This approach represents a low-power, low-cost implementation. Note that these embodiments can be easily extended to larger DSAs, e.g., a 10x10 combiner, which requires a 9-to-1 combiner.

[0128] Figure 73 shows one example of how a combiner 632 can be constructed using multiple combiners 634 in series to create a combiner with a larger spread or to enable phase shifting across multiple pixels. Figure 73 shows two 2-to-1 combiners 634 stacked in series. One might choose to do this because of the SWAP-C or performance characteristics of a 2-to-1 combiner versus a 4-to-1 combiner, or because of the unavailability of the required combiner spread. Another reason might be that it is easier to equalize the total trace lengths from one pixel to another so as not to induce unequal time delays on the signal lines. Additionally, mixers can be placed between the combiners 634 to enable some beamforming and steering between groups.

[0129] Figure 74 shows that the combiner approach need not be homogeneous, i.e., combiner use is not balanced across pixels. In the example of Figure 74, a 3-to-1 combiner 672 connects three pixels with a first signal chain 670, while the fourth pixel has a direct connection to a second signal chain 680. This approach can be useful when a DSA is designed to process multiple signals of interest simultaneously with different power / sensitivity needs. In this case, when full DSA performance is required, two signal chains 670, 680 are combined in the digital domain.

[0130] FIG. 75 shows yet another non-limiting illustrative example, which improves performance by moving the TX and RX paths away from the aperture via a duplexer 690 (which may be a switch, circulator, diplexer, etc.). As shown in FIG. 75, the TX signal chain 700 feeds into a first 4-1 combiner 702, which drives a power amplifier (Pa) 704 and transmits through the DSA's pixels. The RX signal chain 710 receives the signal via a second 4-1 combiner 712 after amplification by a low-noise amplifier (LNA) 714 (which may optionally contain a pre-filter). Here, doubling the number of combiners is required, but performance is thereby improved. The LNA 714 can negate the combiner loss, and because Pa 704 is downstream, it is no longer limited by the combiner's power limitations.

[0131] Figures 76-81 present several further examples with various performance / SWAP-C trade spatial locations. Note that these examples use combiner 632 of Figure 69, which interfaces directly with balun 600. Note that all of these examples could alternatively be implemented with combiner 634 in the second location of Figure 69.

[0132] Figure 76 shows a 5x5 pixel DSA embodiment using combiners 632 that are all 5-to-1 combiners, resulting in four signal chains in horizontal polarization and four signal chains in vertical polarization. This configuration is suitable for powers of two (i.e., 2 n ) channel count, e.g., 2 3 It mates well with commercially available software defined radios (SDRs) with 8 channels. The design allows for simultaneous operation on both polarizations, the ability to measure incident polarization, and the ability to beamsteering and shaping in both azimuth and elevation. A drawback of the design in the context of an exemplary 5x5 pixel DSA is that it employs a 5-to-1 combiner, which is not of general scope.

[0133] Referring to FIG. 77, to alleviate the need for the uncommon 5-to-1 combiner in the context of an exemplary 5×5 pixel DSA, the design of FIG. 77 can be adopted, in which one vertical perimeter and one horizontal perimeter of pixels are not brought into the signal chain, resulting in a slight reduction in the effective aperture area. Thus, only one face of the protrusion 20 is in use. Here, all combiners 632 are 4-to-1 combiners. This approach allows the more common 4×1 combiner spread to be used, since powers of two are most commonly used. To make better use of the unused face, the approach of FIG. 74 can be applied, allowing additional signals of interest to be investigated.

[0134] The approach of Figure 78 is useful when a single polarization is of interest, or when beam steering and shaping are required in only one polarization. Here, rows are connected by combiners 632 provided by four signal chains 630, as already described with reference to Figure 76. However, in the embodiment of Figure 78, columns are combined into a single signal chain 720 by a 4-to-1 combiner 722 that spans four 5-to-1 combiners 724. This configuration is useful, for example, when two signals of interest are in operation and shaping and steering are not required for one of those signals.

[0135] Figure 79 is a DSA architecture that provides a single chain 730 without the ability to measure or control polarization or beamforming / steering. The single signal chain is combined with rows and columns by 2-to-1 combiners 731, each spanning two 4-to-1 combiners 732, which in turn span four 5-to-1 combiners 734. This architecture is useful, for example, for supporting existing single channel radios that require efficient ultra-wideband performance.

[0136] Figure 80 shows a DSA in which each pixel has its horizontal and vertical polarizations combined and is connected to its own signal chain. This approach is useful where low noise and high power efficiency are required, and robust beamforming is required, but the beam pattern and receiving pattern are symmetric in polarization.

[0137] Referring to FIG. 81, one benefit of DSA is its ultra-wide bandwidth and ability to support many signals simultaneously. However, a given DSA implementation may be limited by the bandwidth of the data converters. To mitigate this limitation, the architecture of FIG. 81 can be used in any of the aforementioned embodiments. As shown in FIG. 81, after pixels are combined into rows, columns, or some other configuration, they are then split into multiple converters. Across the transmit (TX) path, multiple DAC converters 750 are coupled to a power amplifier (PA) 754 via combiners 752. Across the receive (RX) path, multiple ADC converters 760 are coupled to a low-noise amplifier (LNA) 764, optionally with a pre-filter 766, via combiners 762. Note that the converters may include appropriate filters and mixers. This architecture is suitable, for example, for reducing the impact of losses in the combiner when an LNA and PA are present.

[0138] Preferred embodiments have been illustrated and described. Obvious modifications and alterations will occur to those skilled in the art upon reading and understanding the preceding detailed description. It is intended that the invention be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.

Claims

1. A radio frequency (RF) aperture, comprising: an interface substrate having a front side and a back side; a linear array of conductive tapered protrusions having bases disposed on a front side of the interface substrate, the linear array of conductive tapered protrusions extending away from the front side of the interface substrate, the conductive tapered protrusions comprising a plurality of faces; RF circuitry disposed on a backside of the interface substrate, the RF circuitry electrically connected to differential RF receiving and / or transmitting elements; each differential RF receiving and / or transmitting element being defined by adjacent faces of adjacent pairs of conductive tapered protrusions of said linear array; the number of differential RF receiving and / or transmitting elements per row of the linear array is one less than the number of conductive tapered protrusions per row of the linear array; An RF aperture wherein the number of differential RF receiving and / or transmitting elements per column of said linear array is one less than the number of conductive tapered protrusions per column of said linear array.

2. The RF aperture of claim 1 , wherein the conductive tapered protrusion is a conductive frusto-conical or conical protrusion.

3. a radome having a recess in the form of a tapered protrusion; The RF aperture of claim 1 or 2, wherein the conductive tapered protrusion is disposed within a tapered-protrusion-shaped recess in the radome.

4. The RF aperture of claim 3 , wherein the conductive tapered protrusion comprises a sheet of metal stamped into a recess in the shape of the tapered protrusion.

5. The RF aperture of claim 1 , wherein the conductive tapered protrusion is a square pyramid with four-fold rotational symmetry.

6. An RF opening as described in claim 5, wherein each conductive tapered protrusion further includes a square apex surface where the four sides of the quadrangular pyramid contact each other.

7. The conductive tapered protrusion is square pyramid with two-fold rotational symmetry, a six-sided hexagonal pyramid with six-fold rotational symmetry, or Triangular pyramid with three-fold rotational symmetry 2. The RF aperture of claim 1, wherein:

8. A radio frequency (RF) aperture, comprising: an interface substrate having a front side and a back side; a linear array of conductive tapered protrusions having bases disposed on a front side of the interface substrate, the linear array of conductive tapered protrusions extending away from the front side of the interface substrate; RF circuitry disposed on a backside of the interface substrate, the RF circuitry electrically connected to a differential RF receiving and / or transmitting element, the differential RF receiving and / or transmitting element being defined by adjacent pairs of conductive tapered protrusions; Equipped with the number of differential RF receiving and / or transmitting elements per row of the linear array is one less than the number of conductive tapered protrusions per row of the linear array; An RF aperture wherein the number of differential RF receiving and / or transmitting elements per column of said linear array is one less than the number of conductive tapered protrusions per column of said linear array.

9. a radome having a recess in the form of a tapered protrusion; The RF aperture of claim 8 , wherein the conductive tapered protrusion is disposed within a tapered-protrusion-shaped recess in the radome.

10. The RF aperture of claim 9 , wherein the conductive tapered protrusion comprises a sheet of metal stamped into a recess in the shape of the tapered protrusion.

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