Free space polarisation adapter

Abstract

A system (100) for testing a vehicle radar is described. The system (100) includes a free space polarization adapter (FSPA (104)) configured to alter a first linear polarization state of an electromagnetic wave from a radar device under test (DUT) to a second polarization state different from the first polarization state; and a re-illuminator (106) adapted to receive the electromagnetic wave from the FSPA (104) having the second polarization state.

Description

Background Technology

[0001] Millimeter waves are generated by oscillations at frequencies between 30 GHz and 300 GHz in the spectrum. Millimeter-wave (mmWave) automotive radar is a key technology used in existing Advanced Driver Assistance Systems (ADAS) and planned autonomous driving systems. For example, mmWave automotive radar is used in ADAS to warn of forward and rear-end collisions. Additionally, mmWave automotive radar can be used to plan autonomous driving systems to implement adaptive cruise control and autonomous parking, and ultimately for autonomous driving on streets and highways. The advantage of mmWave automotive radar compared to other sensor systems is that it can operate in most types of weather and in both light and dark conditions. The adaptability of mmWave automotive radar has reduced costs to a level where it can now be deployed in large quantities. Therefore, mmWave automotive radar is now widely used for long-range, medium-range, and short-range environmental sensing in ADAS. Furthermore, mmWave automotive radar can be widely used in autonomous driving systems currently under development.

[0002] The actual driving environments in which automotive radar can be deployed can vary greatly, and many of these environments can be quite complex. For example, a real-world driving environment can contain numerous objects, and some of these objects have complex reflection and diffraction characteristics that affect the echo signal. The direct consequences of not correctly sensing and / or interpreting the echo signal may be triggering false warnings or inappropriate reactions, or failing to trigger warnings or reactions that should have been triggered, which could potentially lead to an accident.

[0003] Therefore, automakers and automotive radar manufacturers are eager to simulate driving conditions electronically in order to provide optimal accuracy performance for automotive radar systems.

[0004] Single-target radar simulators are known. With growing expectations for improved vehicle radar (such as for advanced "intelligent" purposes like autonomous driving), there is an urgent need to test radar devices and verify their accuracy in locating and / or identifying a large number of targets present in real-world driving situations. However, simulating actual driving scenarios requires simulating multiple targets. Typically, the output of a radar with the device under test consists of single-polarized electromagnetic radiation. However, there is no standard or consensus regarding polarization, so different manufacturers choose different polarizations. The only commonality is the use of linear polarization instead of circular polarization, as the latter changes its azimuth upon reflection from a target. However, linear polarization still allows for free selection between, for example, vertical, horizontal 45°, and -45°.

[0005] This variation in polarization of radar devices under test (DUTs) from different manufacturers requires test equipment to adapt to different input polarizations. Using known equipment, this adaptation is extremely expensive and often complex.

[0006] Therefore, there is a need for a system for testing radar devices that at least overcomes the shortcomings of the known radar simulators described above, wherein the radar devices are used to simulate multiple targets encountered by a radar system. Attached Figure Description

[0007] The exemplary embodiments are best understood from the following detailed description when read in conjunction with the accompanying drawings. It should be emphasized that the various features are not necessarily drawn to scale. In practice, dimensions may be increased or decreased arbitrarily for clarity of discussion. Where applicable and practical, the same reference numerals refer to the same elements.

[0008] Figure 1 This is a simplified block diagram of a system for testing vehicle radar according to a representative implementation.

[0009] Figure 2A This is a cross-sectional view of a free-space polarization adapter based on a representative implementation scheme.

[0010] Figure 2B The following is illustrated based on a representative implementation scheme. Figure 2A The arrangement of traverses at each spatial location in the xy plane of the coordinate system.

[0011] Figure 3A This is an end view of an FSPA comprising multiple elements according to a representative implementation, each element being disposed on a curtain strip.

[0012] Figure 3B This is a simplified conceptual view illustrating a system for testing vehicle radar according to a representative implementation.

[0013] Figure 4 This is an end view of an FSPA comprising multiple curtain strips according to a representative embodiment, each curtain strip comprising multiple elements. Detailed Implementation

[0014] In the following detailed description, representative embodiments with specific details disclosed are set forth for purposes of explanation rather than limitation, in order to provide a thorough understanding of embodiments implemented according to this teaching. Descriptions of known systems, apparatuses, materials, methods of operation, and methods of manufacture may be omitted to avoid obscuring the description of representative embodiments. Nevertheless, systems, apparatuses, materials, and methods within the knowledge of one of ordinary skill in the art are also within the scope of this teaching and may be used according to representative embodiments. It should be understood that the terminology used herein is for describing particular embodiments only and is not intended to be limiting. The defined terminology is supplementary to the technical and scientific meaning of the defined terminology as generally understood and accepted in the technical field of this teaching.

[0015] It will be understood that while the terms first, second, third, etc., may be used herein to describe various elements or components, these elements or components should not be limited by these terms. These terms are used only to distinguish one element or component from another. Therefore, without departing from the teachings of this disclosure, the first element or component discussed below may be referred to as the second element or component.

[0016] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in the specification and appended claims, the singular forms “a,” “an,” and “the” are intended to include both the singular and plural forms, unless the context clearly specifies otherwise. Additionally, when used herein, the terms “comprising” and / or “including” and / or similar terms explicitly state the presence of the stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or groups thereof. As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items.

[0017] Unless otherwise stated, when an element or component is referred to as "connected to" or "coupled to" another element or component, it should be understood that the element or component may be directly connected to or coupled to that other element or component, or that there may be intervening elements or components. That is, these and similar terms cover situations where one or more intermediate elements or components may be used to connect two elements or components. However, when an element or component is referred to as "directly connected to" another element or component, this only covers situations where the two elements or components are connected to each other without any intermediate or intervening elements or components.

[0018] As described herein in conjunction with various representative embodiments, a system for testing vehicle radar is disclosed. The system includes: a free-space polarization adapter (FSPA) configured to change a first polarization state of electromagnetic waves from a radar device under test (DUT) to a second polarization state different from the first polarization state; and a re-illuminator adapted to receive the electromagnetic waves from the FSPA having the second polarization state.

[0019] As described herein with reference to various representative embodiments, a free-space polarization adapter (FSPA) is described. The FSPA is configured to change a first polarization state of an electromagnetic wave to a second polarization state different from the first polarization state. The FSPA includes: a stack of spacer layers disposed in overlapping arrangements; spaces in each of the spacer layers; a support membrane extending across each of the spaces; and a set of wires disposed on each of the support membranes, wherein a set of wires is disposed in each space. Each set of wires is adapted to change the polarization state of the electromagnetic wave to another polarization state.

[0020] As described herein in conjunction with various representative embodiments, a free-space polarization adapter (FSPA) includes: a curtain strip comprising a plurality of elements adapted to change a first polarization state of an electromagnetic wave to a second polarization state different from the first polarization state. Each of the plurality of elements includes: a stack of spacer layers disposed in an overlapping manner; a space between each of the spacer layers; a support membrane extending across each of the spaces; and a set of wires disposed on each of the support membranes, wherein a set of wires is disposed in each space, and wherein each set of wires is adapted to change the polarization state of the electromagnetic wave to another polarization state.

[0021] Figure 1This is a simplified block diagram illustrating a system 100 for testing vehicle radar according to a representative embodiment. As will be understood by those skilled in the art who benefit from this disclosure, one possible vehicle radar is automotive radar used in current and emerging automotive applications with various capabilities. However, it is to be emphasized that the system 100 for testing vehicle radar described herein is not limited to automotive radar systems and can be applied to other types of vehicles, including buses, motorcycles, electric bicycles (e.g., scooters), and other vehicles that may employ vehicle radar systems. According to a representative embodiment, system 100 is arranged to test a radar device under test (DUT) 102 and includes a free-space polarization adapter (FSPA) 104 and a plurality of re-illuminators 106. Each re-illuminator 106 includes a re-illuminator antenna 108 and a radar target simulator (RTS) 110. According to a representative embodiment, the plurality of re-illuminators 106 may be arranged in a 2D array, wherein each re-illuminator 106 represents a pixel in the 2D array. In this case, the pixel (which may be referred to herein as an RTS pixel) has a spatial position corresponding to a target angle.

[0022] Various aspects of the RTS 110 are described in jointly owned U.S. Patent Application No. 16 / 867,804 and jointly owned U.S. Provisional Application No. 62 / 912,442, both of which are inventors of Gregory Lee. The full disclosure of U.S. Patent Application No. 16 / 867,804 and U.S. Provisional Application No. 62 / 912,442 is expressly incorporated herein by reference. It is noteworthy that in U.S. Patent Application No. 16 / 867,804 and U.S. Provisional Application No. 62 / 912,442, the RTS 110 is referred to as a “Modulation Reflection Device (MRD)”. Furthermore, as indicated in these cited applications and as described more fully below, each simulation target has one RTS 110.

[0023] As will become clearer as this specification continues, FSPA 104 may include a single structure comprising multiple elements and adapted to change the polarization state incident on each RTS 110, or may include multiple structures, each comprising multiple elements and each adapted to change the polarization state incident on a particular RTS in RTS 110.

[0024] The system also includes a computer 112. In various embodiments, computer 112 may include one or more computer processors (e.g., processor 118), digital signal processors (DSPs), field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), or combinations thereof, using hardware, software, firmware, hardwired logic circuitry, or any combination thereof. Computer 112 and / or controller 114 may include their own processing memory (e.g., memory 116) to store computer-readable code (e.g., software, software modules) capable of performing the various functions described herein. For example, the processing memory may store software instructions / computer-readable code executable by processor 118 for performing some or all aspects of the embodiments described herein. That is, execution of the instructions / computer-readable code generally causes processor 118 and / or controller 114 of computer 112 to simulate echo signals reflected from a simulated radar target in response to a PMCW signal emitted by radar DUT 102. The memory (and database) described herein can be RAM, ROM, flash memory, electrically programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), register, hard disk, removable disk, magnetic tape, optical disc read-only memory (CD-ROM), digital universal disk (DVD), register, hard disk, removable disk, magnetic tape, floppy disk, Blu-ray disc, or Universal Serial Bus (USB) drive, or any other form of storage medium known in the art that is tangible and non-transitory computer-readable storage medium (e.g., compared to transiently propagating signals). Without departing from the scope of this teaching, the memory can be volatile or non-volatile, secure and / or encrypted, insecure and / or unencrypted.

[0025] Controller 114 may include a combination of memory 116 storing instructions and processor 118 executing instructions to implement the processes described herein. Controller 114 may be housed within or linked to a workstation, such as computer 112 or another component of one or more computing devices, a display / monitor, and one or more input devices (e.g., keyboard, joystick, and mouse) in the form of a standalone computing system, a client computer of a server system, a desktop computer, or a tablet computer. The term “controller” broadly encompasses all structural configurations for controlling dedicated motherboards or application-specific integrated circuits of various principles as described in this disclosure, as understood in the field of this disclosure and as exemplarily described herein. Controller structural configurations may include, but are not limited to, one or more processors, one or more computer-usable / computer-readable storage media, one or more operating systems, one or more application modules, one or more peripheral device controllers, one or more slots, and one or more ports.

[0026] Furthermore, although computer 112 shows networked components, two such components can be integrated into a single system. For example, computer 112 can be integrated with a display (not shown) and / or with system 100. That is, in some embodiments, the functions belonging to computer 112 can be implemented by system 100 (e.g., performed by said system). On the other hand, the networked components of computer 112 can also be spatially distributed, such as by being distributed in different rooms or different buildings, in which case the networked components can be connected via a data connection. In yet another embodiment, one or more components of computer 112 are not connected to other components via a data connection, but rather manually provided with input or output, such as via a memory stick or other form of memory. In yet another embodiment, the functions described herein can be performed based on the elements of computer 112 but outside of system 100.

[0027] Although the various components of system 100 are described in more detail below in conjunction with representative embodiments, a brief description of the functionality of system 100 is presented here.

[0028] In operation, the radar DUT 102 emits a signal (illustratively a millimeter-wave signal) incident on a first side 103 of the FSPA 104. As described more fully herein, the signal from the DUT has a specific linear polarization state. As described more fully below, the FSPA 104 is configured to provide a desired polarization state at a second side 105 that is useful in simulating the polarization state by the re-illuminator 106. By way of example only, if the radar signal from the radar DUT 102 is linearly polarized along the z-axis in the coordinate system shown, and the re-illuminator 106 is adapted to process a radar signal having a polarization state along the x-axis in the coordinate system shown, and therefore said polarization state is incompatible with the polarization state output from the radar DUT 102. As described more fully below, the FSPA 104 is adapted to rotate the first linearly polarized signal incident on its first side 103 from the radar DUT 102 into a second linear polarization state at its second side 105 that is compatible with the polarization state used by the re-illuminator 106. Therefore, continuing with this example, when the radar DUT 102 provides the radar signal in a first linear polarization state oriented along the z-axis of the coordinate system shown to the first side 103, the FSPA 104 rotates the incident radar signal by 90° to a second linear polarization state oriented along the x-axis of the coordinate system shown.

[0029] Again, each signal diffracted by FSPA 104 is incident on a corresponding antenna in re-illuminator antenna 108 of re-illuminator 106. The signal incident on re-illuminator antenna 108 is provided to the corresponding RTS in RTS 110. As described more fully herein, frequency modulation of the incident signal is implemented in each MRD based on input from the controller, and advantageously simulates the target's distance from radar DUT 102, or the target's velocity relative to radar DUT 102, or both. Furthermore, and again as described more fully herein, azimuth is simulated by re-illuminator antenna 108. Figure 1 (±x direction in the coordinate system) and height ( Figure 1 (in the coordinate system of ±z direction), the orientation and height are schematically mechanically omnidirectional or a combination of mechanical omnidirectional movement and electronic simulation.

[0030] The re-illuminated signal is incident on the second side 105 of the FSPA 104, where the polarization state of the re-illuminated signal is rotated to be compatible with the radar DUT 102. Therefore, continuing the previous example, the re-illuminator 106 provides the radar signal in a second linear polarization state (oriented along the x-axis of the illustrated coordinate system) to the second side 105, and the FSPA 104 rotates the incident radar signal by 90° to a first linear polarization state (oriented along the x-axis of the illustrated coordinate system) for reception by the radar DUT 102.

[0031] Figure 2A This is a cross-sectional view of a free-space polarization adapter (FSPA) 200 according to a representative embodiment. Various aspects of the FSPA 200 and its embodiments are related to the above. Figure 1 The representative implementation schemes described share those common aspects. The details of these common aspects are combined... Figure 2A The description of the representative implementation scheme need not be repeated, but it can still be closely related to the implementation scheme described here.

[0032] FSPA 200 comprises alternating stacks of a support film layer 201 and a spacer layer 202. As will become clearer as this specification continues, the support film layer 201 has a relatively low dielectric constant (e.g., <3.5 at millimeter-wave frequencies), relatively low loss (e.g., with a loss tangent δ <0.01), and sufficient to prevent the support film layer 201 from becoming even thinner ( Figure 2AThe relatively large tearing intensity in sheet-like form (z-direction in the coordinate system). According to a representative embodiment, the support film layer 201 is made of a relatively low-loss radio frequency (RF) material and can be made of, for example, Kapton Teflon, Mylar, Tachyon 100G, Getek, and Megtron 6 (using copper wires as discussed below). Depending on the material chosen for use as the support film layer 201, the thickness of these layers ranges from approximately 0.25 mils to approximately 3.0 mils.

[0033] The spacer layer 202 is spaced at essentially uniform intervals that are fractions of the wavelength of free space. Figure 2A The spacers are set in the z-direction of a coordinate system. For example, at 77 GHz, the wavelength is approximately 3.9 mm, and the thickness of each spacer may be approximately 0.15 mm to 0.5 mm (also in the z-direction). Given the space used as a low-loss radiation window (described below), the spacers can be made of one of a variety of materials through which electromagnetic radiation encounters polarized conductors (discussed below). Illustratively, spacer layer 202 can be made of FR-4, as many printed circuit board (PCB) and flexible circuit suppliers have laminated it with Kapton, which can be used to form the support film layer 201 as indicated above.

[0034] As shown, a first set of wires 210 is disposed on the support membrane layer 201. A first space 211 is provided by removing a portion of the spacer layer 202 at this stacked layer.

[0035] As shown, a second set of wires 212 is disposed on the support membrane layer 201. A second space 213 is provided by removing a portion of the spacer layer 202 at this stacked layer.

[0036] As shown, a third set of wires 214 is disposed on the support membrane layer 201. A third space 215 is provided by removing a portion of the spacer layer 202 at this stacked layer.

[0037] As shown, a fourth set of wires 216 is disposed on the support membrane layer 201. A fourth space 217 is provided by removing a portion of the spacer layer 202 at this stacked layer.

[0038] As shown, a fifth set of wires 218 is disposed on the support membrane layer 201. A fifth space 219 is provided by removing a portion of the spacer layer 202 at this stacked layer.

[0039] As shown, a sixth set of wires 220 is disposed on the support membrane layer 201. The sixth space 221 is provided by removing a portion of the spacer layer 202 at this stacked layer.

[0040] As shown, a seventh set of wires 222 is disposed on the support membrane layer 201. A seventh space 223 is provided by removing a portion of the spacer layer 202 at this stacked layer.

[0041] As shown, an eighth set of wires 224 is disposed on the support membrane layer 201. An eighth space 225 is provided by removing a portion of the spacer layer 202 at this stacked layer.

[0042] As shown, the ninth group of wires 226 is disposed on the support membrane layer 201.

[0043] It is important to note that the use of nine wire sets in FSPA 200 is merely illustrative, and more or fewer wire sets can be used to form FSPA 200. As noted below, when determining the number of wire sets and layers in a stack, the trade-off between the cost of more wire sets in a stack including FSPA 200 and the potential increase in losses due to fewer wire sets must be considered.

[0044] Such as combination Figure 2B As described more fully in a representative embodiment, the FSPA 200 is adapted to allow electromagnetic radiation incident on a first opening 230 of a first side 203 in a first polarization state to pass through a first set of conductors 210 to a ninth set of conductors 226 arranged in a first space 211 to an eighth space 225 (each of these spaces includes air), and to exit from a second opening 232 of a second side 205 having a second polarization state different from the first polarization state. Similarly, the FSPA 200 is adapted to allow electromagnetic radiation incident on a second side 205 in a first polarization state to pass through a first set of conductors 210 to a ninth set of conductors 226 arranged in a first set of spaces 211 to an eighth set of spaces 225, and to exit from a first side 203 having a second polarization state different from the first polarization state.

[0045] Figure 2B The following is illustrated based on a representative implementation scheme. Figure 2A The arrangement of the first set of traverses 210 to the ninth set of traverses 226 in the xy plane of the coordinate system at the corresponding spaces in the first space 211 to the eighth space 225.

[0046] Each of the first set of wires 210 to the ninth set of wires 226 forms a wire gate. An electromagnetic wave having its electric field component aligned parallel to the wires in the first set of wires 210 to the ninth set of wires 226 will cause electrons to move along the length of the wires. Since electrons can move freely in this direction, the wire gate behaves similarly to a metal surface when reflecting light, and the wave is reflected backward along the incident beam (minus a small amount of energy lost due to Joule heating of the wires).

[0047] For a wave with an electric field perpendicular to the wires, electrons cannot travel too far across the width of each wire. Therefore, almost no energy is reflected, and the incident wave can pass through the wire grid. In this case, the grid behaves similarly to a dielectric material. Thus, an incoming electromagnetic wave with a polarization state perpendicular to the direction of the wire grid polarizer composed of the first set of wires 210 to the ninth set of wires 226 is emitted. Overall, this causes the wave emitted by each set of wires from the first set of wires 210 to the ninth set of wires 226 to be linearly polarized with the electric field vector perfectly perpendicular to the electric field vector of the corresponding set of wires from the first set of wires 210 to the ninth set of wires 226. Thus, arrow 240 shows the orientation of the electric field vector (and therefore the polarization state) emitted by each set of wires from the first set of wires 210 to the ninth set of wires 226, in each case where the electric field is perpendicular to the arrow at each set of wires from the first set of wires 210 to the ninth set of wires 226.

[0048] like Figure 2B As shown, and as mentioned above, the radar wave emitted by the ninth set of conductors 226 has an electric field vector perpendicular to the radar wave incident on the first set of conductors 210. Thus, in this illustration, the first set of conductors 210 to the ninth set of conductors 226 gradually “twist” the orientation of the electric field vector (indicating the polarization state) so that the resulting emitted electric field vector is orthogonal to the incident electric field vector indicating its linear polarization state. Thus, radar waves incident on the first opening 230 of the radar DUT 102 having a first polarization state exit from the second opening 232 having a second polarization state different from the first polarization state (in this case, orthogonal to the first polarization state). Conversely, radar waves incident on the second opening 232 of the ninth set of conductors 226 of the radar DUT 102 having a first polarization state exit from the first opening 230 having a second polarization state different from the first polarization state (in this case, orthogonal to the first polarization state).

[0049] Furthermore, and as can be seen through a review Figure 2B Understandably, the rotation of the polarization state incident at the first opening 230 relative to the polarization state emitted from the second opening 232 can be customized by selecting the orientation of the first set of conductors 210 relative to the ninth set of conductors 226. That is, the first set of conductors 210 can be oriented toward the incident radar signal from the radar DUT 102, which has a first polarization state. By selecting the orientation of the ninth set of conductors 226 relative to the first set of conductors, the transmitted radar signal emitted from the second opening 232 has a second polarization state, which differs from the first polarization state of the radar wave incident on the first opening 230 from the radar DUT 102.

[0050] According to a representative implementation, each of the first group of conductors 210 to the ninth group of conductors 226 is rotated successively relative to the previous group of conductors by an amount determined based on the desired loss level. Therefore, the smaller the incremental change in orientation between each successive group of conductors in the FSPA 200, the more refined the change in orientation of the electric field vector at each successive group of conductors. Conversely, the coarser the incremental change in orientation of the electric field vector between each successive group of conductors in the FSPA 200, the greater the change in orientation of the electric field vector at each group of conductors. As will be understood, the more refined the change in orientation of the electric field vector between each successive group of conductors in the FSPA 200, the lower the power loss on the FSPA 200; and the coarser the change in orientation of the electric field vector between each successive group of conductors in the FSPA 200, the greater the power loss on the FSPA 200. While relatively small changes in orientation of successive groups of conductors in the FSPA (e.g., a difference of 1° between each successive group of conductors) are desirable, this must be weighed against manufacturing costs. Continuing with the previous example, if the orientation between each successive set of wires is 1°, then the number of sets of wires (and the number of stacked layers including FSPA 200) required to achieve a 90° polarization rotation between the first opening 230 and the second opening 232 would be 90. While possible, this degree of variation is likely financially impractical.

[0051] As an example, to achieve a reasonable trade-off between the power level emitted between the first opening 230 and the second opening 232 and the cost of the FSPA 200, the orientation variation between successive sets of conductors is in the range of approximately 5° to approximately 10°. For this purpose, it is assumed that α is the incremental change in the orientation angle of the conductors between successive sets of conductors from the first set of conductors 210 to the ninth set of conductors 226. Each set of conductors is factored by cos... 2 (α) emits a new, slightly “twisted” polarization, and through the factor sin 2 (α) Repulsion / Reflection. Thus, using nine layers as shown (i.e., α = 10°), based on the emission from the FSPA (e.g., from the second opening 232), the polarization state of the electromagnetic signal incident on the FSPA 200 (e.g., on the first opening 230) from the radar DUT 102 is rotated by 90° to provide cos... (2*9) (10°) = 0.76 or approximately -1.2 dB net emission factor.

[0052] Advantageously, the polarization state of the emitted electromagnetic wave is rotated under adiabatic conditions to be perpendicular to the groups of conductors (e.g., first group of conductors 210 to ninth group of conductors 226) at each layer of the stack including FSPA 200. Thus, by providing a difference between five to nine groups of conductors across the stack including FSPA 200, the first polarization state incident on the first opening 230 (or incident on the second opening 232 from the re-illuminator 206 on the return trip) from radar DUT 102 is rotated to provide a second polarization state to re-illuminator 206, the second polarization state being rotated relative to the first polarization state, for example ±45° or 90°, depending on the successive torsional increments. As will be understood, therefore, by virtue of this teaching, the desired (i.e., customized) degree of rotation between the first and second polarization states can be selected by choosing the variation in orientation between each successive group of conductors constituting FSPA 200 and the number of groups of conductors constituting FSPA 200. Note that in Figure 2B The number of conductors (3) in each of the first group of conductors 210 to the ninth group of conductors 226 shown is for illustrative purposes only. More generally, each of the first group of conductors 210 to the ninth group of conductors 226 has a desired density (i.e., the number of conductors per unit width). For this purpose, for a given density, the number of conductors in each group is proportional to the diameter of the first opening 230 and the second opening 232. The density should be greater than or equal to one conductor per quarter of the free space wavelength (λ / 4). On the other hand, to maintain the manufacturability of the printed circuit, a practical limit of approximately one conductor per 5 mils is carefully observed.

[0053] According to the illustrative embodiment, each of the first group of wires 210 to the ninth group of wires 226 is made of a conductive material (e.g., a metal or metal alloy) selected to provide sufficient conductivity in order to efficiently achieve the rotation of the polarization state of the electric vector passing through the wire. As an example, the wires are made of copper, and the stack constituting FSPA 200 includes a laminate containing Cu-Kapton / FR-4 / Cu-Kapton / FR-4 / ... / Cu-Kapton (wire / support film layer 201 / spacer layer 202 having spaces 211 to 225).

[0054] The spacing between the conductors, including the first group of conductors 210 to the ninth group of conductors 226, must be less than the wavelength of the incident radiation. Additionally, the width of each conductor constituting the first group of conductors 210 to the ninth group of conductors 226 (in...) Figure 2A The thickness of each group of conductors (in the x-direction of the coordinate system) should be smaller compared to the spacing between the conductors. According to a representative embodiment, depending on the wavelength of the electromagnetic signal from the radar DUT 102, the thickness of each group of conductors (in the x-direction of the coordinate system) from the first group 210 to the ninth group 226 should be smaller than the spacing between the conductors. Figure 2AThe z-direction in the coordinate system is in the range of approximately 1.0 μm to approximately 25 μm and the width ( Figure 2A The x-direction in the coordinate system (or the y-direction when a particular set of conductors has been cumulatively rotated to 90°) is in the range of approximately 10 μm to approximately 250 μm. It is worth noting that, for the wavelengths envisioned in this teaching, the wire gates composed of the first set of conductors 210 to the ninth set of conductors 226 can be readily fabricated using known photolithography techniques with appropriate dimensions and relatively close spacing.

[0055] Figure 3A This is an end view of an FSPA 300 comprising multiple elements according to a representative embodiment, each element being disposed on a curtain strip. Various aspects of the FSPA 300 and its embodiments are related to the above. Figures 1 to 2B The representative implementation schemes described share those common aspects. The details of these common aspects are combined... Figure 3A The description of the representative implementation scheme need not be repeated.

[0056] FSPA 300 includes a curtain strip comprising multiple elements for selectively changing the input polarization state. Specifically, each "element" comprises a stack forming an FSPA 200. Thus, there are four (4) FSPA 200s in FSPA 300. Furthermore, each element shows a first set of wires (e.g., Figure 2B The orientation of the first group of conductors 210, which are distinguished by dashed lines at the first opening 230; and the last group of conductors at the second opening 232 (e.g., the ninth group of conductors 226). For ease of description, in Figure 3A The multiple sets of conductors (e.g., the second set of conductors 212 to the eighth set of conductors 224) are not shown in the diagram.

[0057] The curtain-like strip forming the FSPA 300 includes first openings 301, 302, 305, and 308. No wires are present in the first opening 301. It is worth noting that when it is not necessary to change the polarization state of the electromagnetic signal from the radar DUT 102, the first opening is aligned between the radar DUT 102 and one (or more) re-illuminators 106.

[0058] The first opening 302 includes a first set of conductors 303 oriented at 135° and a last set of conductors 304 oriented at 90°. Thus, an electromagnetic signal from the radar DUT 102, having a linear polarization state (electric field vector) perpendicular to the first set of conductors 303, will exit from the second opening having a linear polarization state perpendicular to the last set of conductors 304. Therefore, the first element including the first opening 302, the first set of conductors 303, and the last set of conductors 304 will cause the linearly polarized light from the radar DUT 102 to rotate 45° counterclockwise. Furthermore, and as noted above, the linearly polarized electromagnetic signal transmitted back to the radar DUT 102 from one or more re-illuminators 106 is rotated -45° by the last set of conductors 304 to be perpendicular to the first set of conductors 303 and received at the radar DUT 102.

[0059] The first opening 305 includes a first set of conductors 306 oriented at 180° and a last set of conductors 304 oriented at 45°. Thus, an electromagnetic signal from the radar DUT 102 having a linear polarization state (electric field vector) perpendicular to the first set of conductors 306 will exit from the second opening having a linear polarization state perpendicular to the last set of conductors 307. Therefore, the first element including the first opening 305, the first set of conductors 306, and the last set of conductors 307 will cause the linearly polarized light from the radar DUT 102 to rotate +45° clockwise. Furthermore, and as noted above, the linearly polarized electromagnetic signal transmitted back to the radar DUT 102 from one or more re-illuminators 106 is rotated -45° by the last set of conductors 307 to be perpendicular to the first set of conductors 306 and received at the radar DUT 102.

[0060] The first opening 308 includes a first set of conductors 309 oriented at 45° and a last set of conductors 310 oriented at 90°. Thus, an electromagnetic signal from the radar DUT 102, having a linear polarization state (electric field vector) perpendicular to the first set of conductors 309, will exit from the second opening having a linear polarization state perpendicular to the last set of conductors 310. Therefore, the first element, including the first opening, the first set of conductors 303, and the last set of conductors 304, will cause the linearly polarized light from the radar DUT 102 to rotate clockwise by +45°. Furthermore, and as noted above, the linearly polarized electromagnetic signal transmitted back to the radar DUT 102 from one or more re-illuminators 106 is rotated -45° by the last set of conductors 307 to be perpendicular to the first set of conductors 306 and received at the radar DUT 102.

[0061] As shown, a sequence of elements having the first openings 301, 302, 305, and 308 as described above, and corresponding first and last sets of conductors, repeats along the length of the curtain strip forming the FSPA 300. This arrangement allows a user to select the desired rotation of the incident linearly polarized electromagnetic signal by aligning a desired element, including the first openings 301, 302, 305, and 308, between the radar DUT 102 and one or more re-illuminators 106. Thus, the linearly polarized electromagnetic signal incident on the selected first set of conductors 303, 306, and 309 from the radar DUT 102 is rotated by the corresponding last set of conductors 304, 307, and 310 for reception by one or more re-illuminators 106; and rotated again in the opposite direction to the one or more re-illuminators 106 for reception at the radar DUT 102. Of course, aligning the first opening 301 between the radar DUT 102 and one or more re-illuminators 106 will not cause the linearly polarized electromagnetic signal from the radar DUT 102 or one or more re-illuminators 106 to rotate.

[0062] Finally, and as through review Figure 3A Understandably, apertures A1 to D4 are used to align the desired elements of the FSPA 300 to force the linearly polarized electromagnetic signals from the radar DUT 102 to one or more re-illuminators 106 to rotate as desired, and to cause the linearly polarized electromagnetic signals from one or more re-illuminators 106 to rotate in the opposite direction to the radar DUT 102.

[0063] Figure 3B This is a simplified conceptual view illustrating a system for testing vehicle radar according to a representative embodiment. Various aspects of the FSPA 300 and its implementations are combined with the above. Figures 1 to 3A The representative implementation schemes described share those common aspects. The details of these common aspects are combined... Figure 3B The description of the representative implementation scheme need not be repeated, but it can still be closely related to the implementation scheme described here.

[0064] Figure 3B An FSPA 300 comprising multiple elements in a curtain strip, as described above, is shown. The FSPA 300 is disposed between the radar DUT 102 and the re-illuminator 106. As noted above, according to a representative embodiment, the multiple re-illuminators 106 can be arranged in a 2D array, wherein each re-illuminator 106 represents a pixel in the 2D array. In this case, a pixel (which may be referred to herein as an RTS pixel (see...)) Figure 3B It has a spatial position corresponding to the target angle.

[0065] As shown, the first openings 301, 302, 305, and 308 are arranged along the curtain strip and adapted to move upward / downward (as indicated by arrow 330). In operation, rotation of the desired linearly polarized electromagnetic radiation is achieved by aligning the desired first openings 301, 302, 305, and 308 between the radar DUT 102 and the re-illuminator 106. Figure 3B In the image, the first opening 305 is shown as being aligned in this manner.

[0066] like Figure 3B As shown, when the radar DUT is tested with a different polarization than the previous radar DUT, the curtain strip is shifted along arrow 330, so that the associated first openings 301, 302, 305 and 308 mate with each re-illuminator antenna 108.

[0067] For example, suppose the re-illuminator antenna 108 is designed for horizontal polarization. The curtain strip has a first opening 301, which, instead of a wire assembly, has a hole drilled through the entire laminated stack. Another radar DUT 102 may have a test antenna providing vertical polarization. In this case, the curtain is moved (along arrow 330) so that the first opening 305 is aligned between the radar DUT 102 and the re-illuminator antenna 108. In another instance, it may be necessary to rotate the linearly polarized electromagnetic signal from the radar DUT 102 by +45°. In this case, the curtain is moved (along arrow 330) so that the first opening 308 is aligned between the radar DUT 102 and the re-illuminator antenna 108. Finally, it may be necessary to rotate the linearly polarized electromagnetic signal from the radar DUT 102 by -45°. In this case, the curtain is moved (along arrow 330) so that the first opening 302 is aligned between the radar DUT 102 and the re-illuminator antenna 108. Multiple sets of different PCB mounting holes on the curtain strip ( Figure 3A The mounting holes (A1 to D4) in Figure 2 allow for rapid reinstallation and relocation – then the entire RTS column is immediately adapted to the new radar. The specific geometry of the mounting holes shown in Figure 2 is merely an example; many alternative mounting geometries exist to achieve the same result.

[0068] Figure 4 This is an end view of an FSPA 400 comprising multiple curtain strips according to a representative embodiment, each curtain strip including multiple elements. Various aspects of the FSPA 400 and its embodiments are related to the above. Figures 1 to 3B The representative implementation schemes described herein share those common aspects. The details of these 20 common aspects are combined... Figure 3A The description of the representative implementation scheme need not be repeated.

[0069] FSPA 400 includes features installed in the radar DUT ( Figure 4Multiple FSPAs 300 (not shown) are positioned between multiple re-illuminators 106 (RTS pixels) and a plurality of re-illuminators 106, which can be arranged in a 2D array and have spatial positions corresponding to the target angle. Notably, the 2D array of re-illuminators 106 is arranged... Figure 4 After FSPA 400 in the middle.

[0070] In the illustrative embodiment, the first opening 305 of each FSPA 300 is aligned with the re-illuminator 106 to ensure proper rotation of the incident linearly polarized light from the radar DUT. This alignment is symbolically shown by a triangle disposed in the first opening. As will be understood, another of the first openings 301, 302, 305, and 308 can be aligned by moving the first suspension member 403 and the second suspension member 404 so that they are suspended by the corresponding opening 402 as shown, thereby achieving another desired rotation of the linearly polarized electromagnetic radiation from the radar DUT to match the linearly polarized electromagnetic radiation of the re-illuminator.

[0071] While 2D arrays of illuminators are useful, in some applications, a quasi-cylindrical array of re-illuminators 106 in which adjacent columns are not coplanar is envisioned. A cylindrical arrangement is more advantageous for representing a wide field of view (FOV) of the radar DUT without compromising sensitivity to targets not directly in front of the radar DUT. Thus, the first suspension member 403 and the second suspension member 404 mechanically link the FSPA 300 together, allowing the same result of refitting the entire system with a single action to be achieved by raising and lowering the first suspension member 403 and the second suspension member 404.

[0072] In view of the foregoing, this disclosure, through one or more of its various aspects, embodiments, and / or specific features or sub-components, is therefore intended to provide one or more of the advantages specifically pointed out below. For purposes of explanation and not limitation, exemplary embodiments with specific details disclosed are illustrated to provide a full understanding of embodiments implemented according to this teaching. However, other embodiments consistent with this disclosure but departing from the specific details disclosed herein remain within the scope of the appended claims. Furthermore, descriptions of well-known devices and methods may be omitted so as not to obscure the description of the exemplary embodiments. Such methods and devices are within the scope of this disclosure.

[0073] Although various target simulations for automotive radar systems have been described with reference to several representative embodiments, it should be understood that the language used is descriptive and illustrative, not restrictive. Changes may be made within the scope and spirit of the dynamic echo signal simulation for automotive radar sensor configurations, as presented and modified, without departing from the general principles and spirit of the subject matter. While the dynamic echo signal simulation for automotive radar sensor configurations has been described with reference to specific means, materials, and embodiments, it is not intended to be limited to the disclosed details; rather, it extends to all functionally equivalent structures, methods, and uses, such as those within the scope of the appended claims.

[0074] The descriptions of the embodiments described herein are intended to provide a general understanding of the structure of the various embodiments. The descriptions are not intended to be a complete description of all elements and features of the disclosure described herein. Many other embodiments may be apparent to those skilled in the art upon review of the disclosure. Other embodiments may be utilized and derived from this disclosure, allowing for structural and logical substitutions and changes without departing from the scope of this disclosure. Furthermore, the illustrations are merely representative and may not be drawn to scale. Some scales within the illustrations may be exaggerated, while others may be minimized. Therefore, this disclosure and the accompanying drawings are to be considered illustrative rather than restrictive.

[0075] One or more embodiments of this disclosure may be referred to herein individually and / or collectively by the term "teaching," merely for convenience and not intended to voluntarily limit the scope of this application to any particular invention or inventive concept. Furthermore, although specific embodiments are shown and described herein, it should be understood that any subsequent arrangements designed to achieve the same or similar purpose may replace the specific embodiments shown. This disclosure is intended to cover any and all subsequent modifications or variations to the various embodiments. After reviewing this specification, combinations of the above embodiments and other embodiments not specifically described herein will be apparent to those skilled in the art.

[0076] An abstract of this disclosure is provided to conform to 37 CFR § 1.72(b) and is submitted on the basis that it will not be used to interpret or limit the scope or meaning of the claims. Additionally, in the foregoing detailed description, various features may be combined together or described in a single embodiment to simplify the disclosure. This disclosure should not be construed as reflecting an intention that the claimed embodiments require more features than expressly stated in each claim. Rather, as reflected in the following claims, the subject matter of the invention may address fewer than all features of any of the disclosed embodiments. Therefore, the following claims are incorporated into the detailed description, wherein each claim independently defines a separately claimed subject matter.

[0077] The present invention includes the following embodiments: 1. A system for testing vehicle radar, the system comprising: A free-space polarization adapter (FSPA) configured to change a first linear polarization state of an electromagnetic wave from a radar device under test (DUT) to a second linear polarization state different from the first polarization state; and A re-illuminator adapted to receive the electromagnetic wave having the second linear polarization state from the FSPA. 2. The system according to Clause 1, wherein the re-illuminator is adapted to simulate apparent target distance or apparent target velocity or both. 3. The system according to Clause 1, wherein the re-irradiator comprises: Multiple radar reflector target simulators (RTSs) are included, each RTS comprising: an antenna; a circulator; an in-phase quadrature (IQ) mixer; and a variable gain amplifier (VGA). 4. The system according to Clause 3, wherein the gain or loss of the VGA is selected to map the radar cross section to a corresponding target among multiple targets. 5. The system according to Clause 3, wherein the plurality of MRDs correspond to a plurality of targets. 6. The system according to Clause 3, wherein the FSPA is a single element disposed between the DUT and the plurality of RTSs. 7. The system according to Clause 3, wherein the FSPA includes a plurality of elements, wherein each of the plurality of elements is disposed adjacent to a corresponding RTS in the RTS. 8. The system according to Clause 3, wherein the first polarization state includes one of a plurality of first linear polarization states, and the second polarization state includes one of a plurality of second linear polarization states, and the FSPA includes a plurality of elements, each element being disposed on a curtain strip, each of the plurality of elements being adapted to change one of the plurality of first polarization states to a predetermined second polarization state among the plurality of second polarization states. 9. A free-space polarization adapter (FSPA), the FSPA being configured to change a first polarization state of an electromagnetic wave to a second polarization state different from the first polarization state, the FSPA comprising: Stacking of spacer layers arranged in an overlapping manner; The space between each of the spacer layers; A support membrane extending across each of the spaces; and A set of wires is disposed on each of the support membranes in the support membrane, wherein a set of wires is disposed in each space, and wherein each set of wires is adapted to change the linear polarization state of an electromagnetic wave to another linear polarization state. 10. The FSPA as described in Clause 9, wherein electromagnetic radiation incident on a first space in the space has a first linear polarization state and exits from a last space in the space with a second linear polarization state different from the first polarization state. 11. The FSPA as described in Clause 10, wherein the second linear polarization state is shifted by 90° compared to the first linear polarization state. 12. The FSPA as described in Clause 10, wherein the second polarization state is shifted by ±45° compared to the first linear polarization state. 13. A free-space polarization adapter (FSPA), comprising: A curtain-like strip, the curtain-like strip comprising a plurality of elements adapted to change a first linear polarization state of an electromagnetic wave to a second linear polarization state different from the first linear polarization state, wherein each of the plurality of elements comprises: Stacking of spacer layers arranged in an overlapping manner; The space between each of the spacer layers; A support membrane extending across each of the spaces; and A set of wires is disposed on each of the support membranes in the support membrane, wherein a set of wires is disposed in each space, and wherein each set of wires is adapted to change the linear polarization state of an electromagnetic wave to another linear polarization state. 14. The FSPA as described in Clause 13, wherein an electromagnetic wave incident on a first space in the space has a first linear polarization state and exits from a last space in the space with a second linear polarization state different from the first linear polarization state. 15. The FSPA as described in Clause 14, wherein the second linear polarization state is shifted by 90° relative to the first linear polarization state. 16. The FSPA as described in Clause 10, wherein the second linear polarization state is shifted by ±45° relative to the first polarization state. 17. The FSPA as described in Clause 10, wherein the curtain strip is adapted to move such that one of the plurality of elements is aligned with the output from the DUT. 18. The FSPA as described in Clause 10, further comprising: A plurality of curtain strips, each curtain strip including a plurality of elements adapted to change a first linear polarization state of an electromagnetic wave to a second linear polarization state different from the first linear polarization state, wherein each of the plurality of elements includes: Stacking of spacer layers arranged in an overlapping manner; The space between each of the spacer layers; A support membrane extending across each of the spaces; and A set of wires is disposed on each of the support membranes in the support membrane, wherein a set of wires is disposed in each space, and wherein each set of wires is adapted to change the linear polarization state of an electromagnetic wave to another linear polarization state. 18. The FSPA as described in Clause 17, wherein the plurality of curtain strips are arranged to be adjacent to each other. 19. The FSPA as described in Clause 18, wherein the plurality of curtain strips are suspended between the first member and the second member. 20. The FSPA as described in Clause 19, wherein the first and second rods are adapted to move the plurality of curtain strips such that a desired element of the plurality of elements aligns one of the plurality of elements of each of the plurality of curtain strips with an output from the DUT.

[0078] The foregoing description of the disclosed embodiments is provided to enable any person skilled in the art to practice the concepts described in this disclosure. Thus, the subject matter disclosed above should be considered illustrative rather than restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments falling within the true spirit and scope of this disclosure. Therefore, to maximize legal permissibility, the scope of this disclosure should be determined by the broadest permissible interpretation of the following claims and their equivalents and should not be bound or limited by the foregoing detailed description.

Claims

1. A system for testing vehicle radar, the system comprising: A free space polarization adapter (FSPA) is configured to change a first linear polarization state of an electromagnetic wave from a radar device under test (DUT) to a second linear polarization state that is different from the first linear polarization state. as well as A re-illuminator adapted to receive the electromagnetic wave having the second linear polarization state from the FSPA.

2. The system according to claim 1, wherein, The re-illuminator is adapted to simulate apparent target distance or apparent target velocity, or both.

3. The system according to claim 1, wherein, The re-irradiator includes: Multiple radar reflector target simulators (RTSs) are included, each RTS comprising: an antenna; a circulator; an in-phase quadrature (IQ) mixer; and a variable gain amplifier (VGA).

4. The system according to claim 3, wherein, Select the gain or loss of the VGA to map the radar cross section to the corresponding target among multiple targets.

5. The system according to claim 3, wherein, The multiple RTSs are equivalent to multiple targets.

6. The system according to claim 3, wherein, The FSPA is a single element disposed between the DUT and the plurality of RTSs.

7. The system according to claim 3, wherein, The FSPA includes a plurality of elements, wherein each of the plurality of elements is disposed adjacent to a corresponding RTS in the RTS.

8. The system according to claim 3, wherein, The first linear polarization state includes one of a plurality of first linear polarization states, and the second linear polarization state includes one of a plurality of second linear polarization states, and the FSPA includes a plurality of elements, each element being disposed on a curtain strip, each of the plurality of elements being adapted to change one of the plurality of first linear polarization states to a predetermined second linear polarization state among the plurality of second linear polarization states.

9. A free-space polarization adapter (FSPA), the FSPA being configured to change a first polarization state of an electromagnetic wave to a second polarization state different from the first polarization state, the FSPA comprising: The supporting membrane layer (201) and the spacer layer (202) are stacked alternately; A plurality of spaces are formed in the stack, wherein each space is provided by removing a portion of the spacer layer (202) at a corresponding layer of the stack, and each space includes air; A support membrane extending across each of the spaces; and A set of wires is disposed on each of the support membranes in the support membrane, wherein a set of wires is disposed in each space, and wherein each set of wires is adapted to change the linear polarization state of an electromagnetic wave to another linear polarization state.

10. The FSPA according to claim 9, wherein, Electromagnetic radiation incident on a first space among the plurality of spaces has a first linear polarization state and exits from the last space among the plurality of spaces with a second linear polarization state different from the first polarization state.

11. The FSPA according to claim 10, wherein, The second linear polarization state is shifted by 90° compared to the first linear polarization state.

12. The FSPA according to claim 10, wherein, The second polarization state is shifted compared to the first linear polarization state. + 45°.

13. A free-space polarization adapter (FSPA), comprising: A curtain-like strip, the curtain-like strip comprising a plurality of elements adapted to change a first linear polarization state of an electromagnetic wave to a second linear polarization state different from the first linear polarization state, wherein each of the plurality of elements comprises: Stacking of spacer layers arranged in an overlapping manner; The space between each of the spacer layers; A support membrane extending across each of the spaces; and A set of wires is disposed on each of the support membranes in the support membrane, wherein a set of wires is disposed in each space, wherein each set of wires is adapted to change the linear polarization state of an electromagnetic wave to another linear polarization state, wherein an electromagnetic wave incident on a first space in the space has a first linear polarization state and exits from a last space in the space with a second linear polarization state different from the first linear polarization state.

14. The FSPA according to claim 13, wherein, The second linear polarization state is shifted by 90° relative to the first linear polarization state.

15. The FSPA according to claim 13, wherein, The second linear polarization state is shifted relative to the first linear polarization state. + 45°.

16. The FSPA according to claim 13, wherein, The curtain strip is adapted to move so that one of the plurality of elements is aligned with the output from the DUT.

17. The FSPA of claim 13, further comprising: A plurality of curtain strips, each curtain strip including a plurality of elements adapted to change a first linear polarization state of an electromagnetic wave to a second linear polarization state different from the first linear polarization state, wherein each of the plurality of elements includes: Stacking of spacer layers arranged in an overlapping manner; The space between each of the spacer layers; A support membrane extending across each of the spaces; and A set of wires is disposed on each of the support membranes in the support membrane, wherein a set of wires is disposed in each space, and wherein each set of wires is adapted to change the linear polarization state of an electromagnetic wave to another linear polarization state.

18. The FSPA according to claim 17, wherein, The plurality of curtain strips are arranged to be adjacent to each other.

19. The FSPA according to claim 17, wherein, The plurality of curtain-like strips are suspended between the first rod and the second rod.

20. The FSPA according to claim 19, wherein, The first and second rods are adapted to move the plurality of curtain strips such that a desired element among the plurality of elements aligns one of the plurality of elements of each of the plurality of curtain strips with an output from the DUT.

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