As wireless systems and infrastructures are strained, and poised to reach limits, there is a need for systems and designs that meet these challenges. Similarly, from driver-assisted to autonomous vehicles, there is a need for advanced sensing and detection at millimeter wave frequencies and under challenging conditions. Developing devices that operate under these constraints and within these frequencies is challenging.
The present application may be more fully appreciated in connection with the following detailed description taken in conjunction with the accompanying drawings, which are not drawn to scale, and in which like reference characters refer to like parts throughout, and in which:
Methods and apparatuses for an active radiating and feed structure are disclosed. The active radiating and feed structure is suitable for many different millimeter wave (“mm-wave”) applications and can be deployed in a variety of different environments and configurations. Mm-wave applications are those operating with frequencies between 30 and 300 GHz or a portion thereof, including autonomous driving applications in the 77 GHz range and 5G applications in the 60 GHz range, among others. The active radiating and feed structure disclosed herein provides antennas with unprecedented capability of generating radio frequency (“RF”) waves with improved directivity in both 5G and autonomous driving applications. Active components in the antennas are used to achieve smart beam steering and beam forming, reducing the antennas' complexity and processing time and enabling fast scans of up to approximately a 360° Field-of-View (“FoV”) for long range target detection.
It is appreciated that, in the following description, numerous specific details are set forth to provide a thorough understanding of the examples. However, it is appreciated that the examples may be practiced without limitation to these specific details. In other instances, well-known methods and structures may not be described in detail to avoid unnecessarily obscuring the description of the examples. Also, the examples may be used in combination with each other.
Radiating structure 102 is capable of radiating dynamically controllable and highly-directive RF beams. Radiating structure 102 has a feed coupling structure 120, a transmission array structure 122, and a radiating array structure 124. When a transmission signal is provided to the radiating structure 102, such as through circuitry, a coaxial cable, a wave guide, or other type signal feed connector, the signal propagates through the feed coupling structure 120 to the transmission array structure 122 and then to radiating array structure 124 for transmission through the air as a radio frequency (“RF”) beam. A variety of signals may be provided to the radiating structure 102 for transmission, such as from a transmission signal controller 110 through a transceiver 106.
In an example application, the radiating structure 102 can be implemented in a radar sensor for use in a driver-assisted or autonomous vehicle. The transmission signal may be a Frequency Modulated Continuous Wave (“FMCW”) signal, which is used for radar sensor applications as the transmitted signal is modulated in frequency, or phase. The FMCW signal enables a radar to measure range to a target by measuring timing and phase differences in phase or frequency between the transmitted signal and the received or reflected signal. Within FMCW formats, there are a variety of modulation patterns that may be used within FMCW, including triangular, sawtooth, rectangular and so forth, each having advantages, challenges, and application for various purposes. For example, sawtooth modulation may be selected for use when detection involves large distances to a target, i.e., long range. In some examples, the shape of the wave form provides speed and velocity information based on the Doppler shift between signals. This information enables construction of a range-Doppler map to indicate a location and movement of a detected object. As used herein, a target is any object detected by the radar, but may also refer to a specific type of object, e.g., a vehicle, a person, a road sign, and so on.
In another example application, the radiating structure 102 is applicable in a wireless communication or cellular system, implementing user tracking from a base station, fixed wireless location, and so on, or function as a wireless relay to provide expanded coverage to users in a wireless network. The transmission signal in cellular communications is a coded signal, such as a cellular modulated Orthogonal Frequency Division Multiplexed (“OFDM”) signal. Other types of signals may also be used with radiating structure 102, depending on the desired application.
Transceiver module 106 coupled to the radiating structure 102 prepares a signal for transmission, wherein the signal is defined by modulation and frequency. The signal is provided to the radiating structure 102 through a coaxial cable or other connector and propagates through the radiating structure 102 for transmission through the air via RF beams at a given phase and direction. The RF beams and their parameters (e.g., beam width, phase, azimuth and elevation angles, etc.) are controlled by antenna controller 108, such as at the direction of AI module 104.
The RF beams reflect off of targets and the RF reflections are received by the transceiver module 106. Radar data from the received RF beams is provided to the AI module 104 for target detection and identification. The radar data may be organized in sets of Range-Doppler (“RD”) map information, corresponding to 4D information that is determined by each RF beam radiated off of targets, such as azimuthal angles, elevation angles, range, and velocity. The RD maps may be extracted from FMCW radar pulses and contain both noise and systematic artifacts from Fourier analysis of the pulses. The AI module 104 may control further operation of the radiating structure 102 by, for example, providing beam parameters for the next RF beams to be radiated from the radiating structure 102.
In operation, the antenna controller 108 is responsible for directing the radiating structure 102 to generate RF beams with determined parameters such as beam width, transmit angle, and so on. The antenna controller 108 may, for example, determine the parameters at the direction of the AI module 104, which may at any given time want to focus on a specific area of an FoV upon identifying targets of interest in a vehicle's path or surrounding environment. The antenna controller 108 determines the direction, power, and other parameters of the beams and controls the radiating structure 102 to achieve beam steering in various directions. The antenna controller 108 also determines a voltage matrix to apply to reactance control mechanisms or devices in radiating structure 102 to achieve a given phase shift. In various examples, the radiating structure 102 is adapted to transmit a directional beam through active control of the reactance parameters of individual radiating elements in radiating array structure 124. The radiating structure 102 radiates RF beams having the determined parameters. The RF beams are reflected off of targets (e.g., in a 360° FoV) and are received by the transceiver module 106.
In various examples described herein, the use of system 100 in an autonomous driving vehicle provides a reliable way to detect targets in difficult weather conditions. For example, historically a driver will slow down dramatically in thick fog, as the driving speed decreases with decreases in visibility. On a highway in Europe, for example, where the speed limit is 115 km/h, a driver may need to slow down to 40 km/h when visibility is poor. Using the radar system 100, the driver (or driverless vehicle) may maintain the maximum safe speed without regard to the weather conditions. Even if other drivers slow down, a vehicle enabled with the system 100 will be able to detect those slow-moving vehicles and obstacles in the way and avoid/navigate around them.
Additionally, in highly congested areas, it is necessary for an autonomous vehicle to detect objects in sufficient time to react and take action. The examples provided herein for system 100 increase the sweep time of a radar signal so as to detect any echoes in time to react. In rural areas and other areas with few obstacles during travel, the system 100 adjusts the focus of the beam to a larger beam width, thereby enabling a faster scan of areas where there are few echoes. The AI module 104 may detect this situation by evaluating the number of echoes received within a given time period and making beam size adjustments accordingly. Once a target is detected, the AI module 104 determines how to adjust the beam focus. This is achieved by changing the specific configurations and conditions of the radiating structure 102.
All of these detection scenarios, analysis and reactions may be stored in the AI module 104 and used for later analysis or simplified reactions. For example, if there is an increase in the echoes received at a given time of day or on a specific highway, that information is fed into the antenna controller 108 to assist in proactive preparation and configuration of the radiating structure 102.
In operation, the antenna controller 108 receives information from AI module 104 or other modules in system 100 indicating a next radiation beam, wherein a radiation beam may be specified by parameters such as beam width, transmit angle, transmit direction and so forth. The antenna controller 108 determines a voltage matrix to apply to reactance control mechanisms or devices in radiating structure 102 to achieve a given phase shift or other parameters. In these examples, the radiating structure 102 is adapted to transmit a directional beam without using digital beam forming methods, but rather through active control of the reactance parameters of the individual radiating elements that make up radiating array structure 124. In one example scenario, the voltages on the reactance control devices in radiating array structure 124 are adjusted. In other examples, the individual radiating elements may be configured into subarrays that have specific characteristics. This configuration means that this subarray may be treated as a single unit, and all the reactance control devices are adjusted similarly. In another scenario, the subarray is changed to include a different number of radiating elements, where the combination of radiating elements in a subarray may be changed dynamically to adjust to conditions and operation of the system 100.
Each of the structures 120-124 in radiating structure 102 is now described in more detail.
Feed coupling structure 200 includes an external feed port 202 adapted to receive a transmission signal such as by way of a coaxial cable or other signal source. The external feed port 202 interfaces with coplanar feed structure 204 for propagation of the received transmission signal. The coplanar feed structure 204 then interfaces with the integrated feed structure 206, which is integrated within a substrate, wherein the received transmission signal propagates through the substrate to the coupling matrix 208. The integrated feed structure 206 includes transmission paths along the substrate through which the transmission signal propagates and may include vias through the substrate to form wave guide structures in order to maintain the transmission signal within the transmission paths of the integrated feed structure 206. Such vias prevent the transmission signal from significantly propagating out of the integrated feed structure 206. The coupling matrix 208 couples the integrated feed structure 206 with the transmission array structure 122 of
An example coupling matrix 208 for use in the feed coupling structure 200 is illustrated in
Referring now to
The transmission array structure 400, as illustrated in
Each row of the transmission array 400 has multiple discontinuities, slots or openings 402, formed into the substrate, through which the propagated signal will radiate. As illustrated, there are multiple slots 402, such as the four (4) slots illustrated per row. In this illustration, there are 4 slots per row the slots of adjacent rows are offset from one another by one column length. In this configuration, the slots 402 correspond positionally to the radiating elements of the radiating array structure 124 of
The propagating signal radiates through a slot 402 to a proximate radiating element, from which the signal is transmitted through the environment. The slots in the transmission array structure 400 are formed lengthwise throughout each row. Each row can be thought of as a waveguide. The effective waveguide structure is bounded by conductive vias along its length and grounded at its end. The dimensions are designed such that the waveguide end is an equivalent open circuit, avoiding signal reflections. The distance between the center of a slot in a row of transmission array structure 400 and the center of an adjacent equidistant slot is shown as λg/2, where λg is the guide wavelength.
In another example, transmission array structure 506 is connected to a feed coupling structure as shown in
Another example transmission array structure is illustrated in
It is appreciated that the slots in transmission array structures 400 and 600 are shown to have a rectangular shape for illustration purposes only. Slots may be designed to have different shapes, orientations and be of different sizes, depending on the desired application. There could also different variations in the number of slots. A transmission array structure may be a 4×4 array, an 8×8 array, a 16×16 array, a 32×32 array, a 4×8 array, a 4×16 array, an 8×32 array, and so on. An example of such a transmission array is shown in
Attention is now directed to
As illustrated, the radiating elements' hexagonal shape provides design flexibility for a densely packed array. Each radiating element has an outer geometric shape, referred to herein as a hexagonal conductive loop, e.g., loop 904, and an inner geometric shape that is referred to as a hexagonal conductive patch, e.g., patch 906. The hexagonal shape provides the flexibility of design for a densely packed array, and the parametric shape enables computational design that can be easily scaled and modified while maintaining the basic shape of the hexagon. The outer geometric shape is referred to herein as a hexagonal loop 904 and 910; and the circumscribed inner geometric shape is referred to as a hexagonal patch 906 and 912. In this example, the dimensions of the shapes are geometrically similar and their relationship is proportionally maintained.
As illustrated, the sides of the hexagonal loop 910 are designated by reference letter “a” and the sides of the hexagonal patch 912 are designated by reference letter “b”. The hexagonal patch 912 is centered within the hexagonal loop 910. Corresponding points on the perimeters of the loop and patch are equidistant from each other, specifically in this example, at a distance designated by “d”. This configuration is repeated to form a densely packed lattice.
In various examples, a radiating element is a metamaterial element. A metamaterial is an artificially structured element used to control and manipulate physical phenomena, such as the electromagnetic (“EM”) properties of a signal including its amplitude, phase, and wavelength. Metamaterial structures behave as derived from inherent properties of their constituent materials, as well as from the geometrical arrangement of these materials with size and spacing that are much smaller relative to the scale of spatial variation of typical applications. A metamaterial is not a tangible new material, but rather is a geometric design of known materials, such as conductors, that behave in a specific way. A metamaterial element may be composed of multiple microstrips, gaps, patches, vias, and so forth, having a behavior that is the equivalent to a reactance element, such as a combination of series capacitors and shunt inductors. Various configurations, shapes, designs and dimensions may be used to implement specific designs and meet specific constraints. In some examples, the number of dimensional degrees of freedom determines the device characteristics, wherein a device having a number of edges and discontinuities may model a specific-type of electrical circuit and behave in a similar manner. In this way, a radiating element radiates according to its configuration. Changes to the design parameters of a radiating element result in changes to its radiation pattern. Where the radiation pattern is changed to achieve a phase change or phase shift, the resultant structure is a powerful antenna or radar, as small changes to the radiating element can result in large changes to the beamform.
In various examples, a metamaterial radiating element has some unique properties. These properties may include a negative permittivity and permeability resulting in a negative refractive index; these structures are commonly referred to as left-handed materials (“LHM”). The use of LHM enables behavior not achieved in classical structures and materials, including interesting effects that may be observed in the propagation of electromagnetic waves, or transmission signals. Metamaterials can be used for several interesting devices in microwave and terahertz engineering such as antennas, sensors, matching networks, and reflectors, such as in telecommunications, automotive and vehicular, robotic, biomedical, satellite and other applications. For antennas, metamaterials may be built at scales much smaller than the wavelengths of transmission signals radiated by the metamaterial. Metamaterial properties come from the engineered and designed structures rather than from the base material forming the structures. Precise shape, dimensions, geometry, size, orientation, arrangement and so forth result in the smart properties capable of manipulating EM waves by blocking, absorbing, enhancing, or bending waves.
In
In some examples, the lattice structure of a radiating array structure is formed by an array of individual radiating elements having dimensions that allow control of the phase of a radiating transmission by changing an effective reactance of the element through application of a voltage to a varactor. The radiating element may take any of a variety of shapes and configurations and be formed as conductive traces on a substrate including a dielectric layer. The varactor control may be thought of as a reactance control array, wherein each of the varactors is controlled by an individual reverse bias voltage resulting in an effective capacitance change to at least one individual radiating element. The varactor then controls the phase of the transmission of each radiating element, and together the entire radiating array structure transmits am electromagnetic radiation beam having a desired phase.
Graph 1208 illustrates how the varactor 1202's capacitance changes with the applied voltage. The change in reactance of varactor 1202 changes the behavior of the radiating element 1200, enabling a radiating array structure 124 to provide focused, high gain beams directed to a specific location. Each beam may be directed to have a phase that varies with the reactance of the varactor 1202, as shown in graph 1210 illustrating the change in phase with the change in reactance of varactor 1202. With the application of a control voltage to the varactor 1202, the radiating element 1200 is able to generate beams at any direction about a plane.
An example radiating array structure incorporating radiating elements with a reactance control device is shown in
As described above, radiating elements can be grouped together in a radiating array structure as subarrays and controlled as a single unit.
Attention is now directed to
A flowchart for manufacturing a wireless transmission device with the radiating structure in
A flowchart for operating a radiating structure in accordance with various examples is illustrated in
The present inventions provide methods and apparatuses for radiating a signal. The methods and apparatuses are applicable in a variety of technical areas, including self-driving cars, truck platooning, drones, navigational devices, hospital monitoring devices, research and nanotechnology monitoring, cellular communication systems and more. Some of these applications are illustrated in
It is appreciated that the previous description of the disclosed examples is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to these examples will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other examples without departing from the spirit or scope of the disclosure. Thus, the present disclosure is not intended to be limited to the examples shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
This application claims priority to U.S. Provisional Application No. 62/558,198, filed on Sep. 13, 2017, and incorporated herein by reference.
Number | Date | Country | |
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62558198 | Sep 2017 | US |