Radar using personal phone, tablet, PC for display and interaction

A portable radar system that may leverage the processing power, input and/or display functionality in mobile computing devices. Some examples of mobile computing devices may include mobile phones, tablet computers, laptop computers and similar devices. The radar system of this disclosure may include a wired or wireless interface to communicate with the mobile computing device, or similar device that includes a display. The radar system may be configured with an open set of instructions for interacting with an application executing on the mobile computing device to accept control inputs as well as output signals that the application may interpret and display, such as target detection and tracking. The radar system may consume less power than other radar systems. The radar system of this disclosure may be used for a wide variety of applications by consumers, military, law enforcement and commercial use.

TECHNICAL FIELD

The disclosure relates to radar and radar displays.

BACKGROUND

Existing radar systems are typically expensive, bulky, consume a significant amount of power, and require expertise in radar systems to configure and use. Some examples of existing radar systems include a rotating antenna and proprietary display and control units.

SUMMARY

In general, the disclosure is directed to a low cost, portable radar system that may leverage the processing power, input and/or display functionality in mobile computing devices. Some examples of mobile computing devices may include mobile phones, tablet computers, personal computers such as laptop computers and similar devices. The radar system of this disclosure may include a wired or wireless interface to communicate with the mobile computing device, or similar device that includes a display. The radar system may be configured with an open set of instructions for interacting with an application executing on the mobile computing device to accept control inputs as well as output signals that the application may interpret and display, such as target detection and tracking. The radar system may consume less power than other radar systems. The radar system of this disclosure may be used for a wide variety of applications by consumers, military, law enforcement and commercial use.

In one example the disclosure is directed to a radar system comprising: a transmit array comprising a plurality of transmit antenna elements, radar transmitter electronics in signal communication with the transmit array, wherein the radar transmitter electronics, in conjunction with the transmit array, are configured to output a frequency modulation continuous wave (FMCW) transmit beam that illuminates an area with a greater extent in a first illumination direction than in a second illumination direction. The second illumination direction is substantially perpendicular to the first illumination direction. The radar system further comprises a receive array comprising a plurality of receive antenna elements, and radar receiver electronics operable to: receive a plurality of receive signals from the receive array, and processing circuitry operable to: digitally form a receive beam from the plurality of receive signals, determine one or more characteristics of a sub-area of the area illuminated by the FMCW transmit beam, wherein the sub-area is within the receive beam, establish a communication session with an external display device, and output a signal to an external display device. The signal to the external display device may comprise: target detection information in three dimensions, the three dimensions including range, azimuth and elevation, and target movement characteristics, including relative velocity and angular velocity.

DETAILED DESCRIPTION

This disclosure is directed to a radar system that leverages the processing power, input functionality and/or display functionality in mobile computing devices. The radar system of this disclosure includes features that may enable the radar system to be manufactured at a low cost and in a portable form factor. Some examples of mobile computing devices that may be used in conjunction with the radar devices described herein include mobile phones, tablet computers, laptop computers and similar devices. The radar system of this disclosure may include a standard wired or wireless interface to communicate with the mobile computing device, or other device that includes a display. The radar system may communicate with an application executing on the mobile computing device to accept control inputs and output low level signals, such as target detection and tracking, that the application may interpret and display. The radar system of this disclosure may be used for a wide variety of applications by consumers, military, law enforcement, and commercial use. Some examples may include hand-held use, such as attaching the portable radar system directly to a mobile computing device, installing the portable radar system in an unmanned vehicle, such as a ground robot or aerial vehicle, or other vehicle such as a boat. In some examples, the signal output to the external display device is compatible with a synthetic vision system (SVS).

Some examples of inputs that a portable radar system of this disclosure may be configured to accept include mode settings such as vehicle detection, navigation mode and the like. Other examples of inputs include global positioning system (GPS) location information.

A portable radar system of this disclosure may consume less power than other radar systems and be configured with an open set of application program interface (API) instructions. An API is a set of routines, protocols, and tools for building software applications. An API specifies how software components interact and is a set of commands, functions, protocols, and objects that programmers can use to create software or interact with an external system. An API provides developers with standard commands for performing common operations, which simplifies code development.

FIG. 1Ais a conceptual diagram illustrating an example portable radar system according to one or more techniques of this disclosure. ThoughFIG. 1Adepicts one example application, other example applications, compatible with the system ofFIG. 1A, will be discussed below, and furthermore, the radar system of this disclosure may be useful for numerous other applications not explicitly mentioned in this disclosure.

The arrangement ofFIG. 1Adepicts portable radar system10connected to a mobile computing device12via communication link14. Portable radar system10is configured to generate transmit beam22and receive reflections of transmit beam22. In some examples, operator20may view the output of portable radar system10and provide inputs to portable radar system10via mobile computing device12.

Portable radar system10may detect and track targets by receiving radar signals reflected from the targets, i.e., reflections of transmit beam22that reflect from the targets. Portable radar system10processes the received radar signals and provides an output, which may be received and interpreted by mobile computing device12. Some examples of targets include vehicles, such as unmanned aerial vehicles (UAV) or boats, structures, such as buildings or river locks, natural land masses, such as a mountain and similar targets. In some examples, radar receiver electronics are operable to detect targets of a cross-sectional area of half a square meter (0.5 m2) at a range of one nautical mile (1 nm). A nautical mile is approximately 1852 meters or 2000 yards.

Portable radar system10may be manually aimed to place an area of interest (AOI) within the field of regard (FOR) of portable radar system10. In some examples, portable radar system10may be a hand-held device, which may be connected, either wired or wirelessly, to mobile computing device12. Mobile computing device12may be any sort of mobile computing device, such as a hand held mobile computing device such as a smart phone or a tablet computer, or mobile computing device12may be a larger device such as a personal computer. Operator20may point portable radar system10toward an AOI and review the output from portable radar system10on mobile computing device12. In other examples, portable radar system10may be mounted to an object, such as a stake or pole and manually aimed toward an AOI. In other examples, portable radar system10may be mounted to a vehicle, such as the mast of a boat, on an aircraft, UAV or other vehicle.

Portable radar system10may include a transmit and receive antennae, processing circuitry, a power supply, and one or more input and output (I/O) connection. The antennae, processing circuitry and other components may be configured as a single, integrated unit. In other words, portable radar system10may be a radar system configured to manage all the radar signal processing tasks and output target information to a computing device or display, such as mobile computing device12.

Communication link14may be a wired or wireless communication link. Some examples of wired communication include Ethernet, universal serial bus (USB) or similar wired communication links. Examples of wireless communication links may include inductive communication, Bluetooth, WiFi, or other similar wireless communications or signal transfer.

Portable radar system10may output transmit beam22as a high aspect ratio FMCW transmit beam that is wider in first illumination direction24than a second direction (i.e., a direction going into or coming out of the page with respect toFIG. 1A). In some examples, the first illumination direction is the horizontal direction with respect to a ground surface. Portable radar system10may include processing circuitry configured to digitally form a receive beam from the receive signals reflected from targets in the portable radar system's FOR. In other words, portable radar system10may use digital beam forming (DBF), including monopulse receive beams, to determine characteristics of a target.

Portable radar system10may include an open API that both outputs target information in a standardized format as well as receives commands and other inputs. Unlike other radar systems, portable radar system10provides flexibility and simplicity for developers to interact with portable radar system10to both display target information and provide inputs to portable radar system10. Existing radar systems typically require a proprietary display device that only works with a particular radar system. Existing radar systems are also typically configured with a limited set of outputs and accept very few, if any inputs to adjust the function of the radar system.

In contrast, portable radar system10may be configured to receive inputs to control the functions of portable radar system10depending on the operating conditions from users via a simple, non-proprietary application, such as an iOS or Android-based application running on a smartphone or tablet. For example, portable radar system10may be mounted in a marine vessel, such as a boat, occupied by operator20. Operator20may select a navigation mode in an application executing on mobile computing device12. The selected navigation mode may cause portable radar system10to respond to input from mobile computing device12by changing a modulation frequency, transmit frequency or other radar parameter to better display land masses or structures that may be used for navigation. In another example, operator20may select a target tracking mode that causes portable radar system10to respond by adjusting radar operating parameters to emphasize vessels nearby that may be a collision hazard for operator20. Some examples additional operating parameters that transmit electronics are further operable to change may include the modulation waveform, modulation bandwidth or chirp time of the FMCW transmit beam. In other words, in some examples, one of the features of portable radar system10that operator20may modify via mobile computing device12is to change the receiver beam scanning strategy to optimize the performance of the intended application via the API programming. The beam scanning may be adjusted in both azimuth (AZ) and elevation (EL) directions

Portable radar system10may provide advantages over existing radar systems that output radar sensor information to an external display device. Existing radar systems may be limited to proprietary display devices that only work with the particular radar system. Some examples of existing radar systems include a rotating antenna which requires complex set up. In contrast, the portable radar system of this disclosure may be small, portable, consume low power that may be provided by a small battery, output a low power transmit beam that is safe for handheld operation, such as mounted to a mobile computing device12. In contrast, some examples of existing radar systems consume significantly more power, and the output power of the transmit beam may require a minimum safe distance from an operator, such as operator20.

Other examples of existing radar systems include portable radar systems. In these examples, however, the existing portable radar systems may have limited or no input or control capability, other than turning the existing portable radar system on or off Examples of these existing portable radar systems include radar systems such as those used on vehicles, such as automobiles, to detect the distance to other vehicles on the road. These existing radar systems may also be limited to outputting information that requires an in-depth understanding of radar systems to interpret and display.

In contrast, portable radar system10of this disclosure may be configured to accept various control inputs from a computing device, such as mobile computing device12. The inputs to portable radar system10may adapt the operation of portable radar system10to change transmit frequencies, modulation scheme or frequency and other operating parameters to adapt operation to a particular application. For example, portable radar system10may receive inputs to operate in a first manner when configured to detect personnel or small vehicles near a military encampment or border control application. Portable radar system10may operate in a different manner when configured for navigation onboard a boat operating in a low visibility environment, such as fog. In some examples, portable radar system10may operate in the millimeter wave frequency range. In other examples, portable radar system10may operate in the microwave frequency range.

Portable radar system10, of this disclosure also may output target and obstacle detection information in a format that an application developer for a computing device may incorporate into an application to display and interpret. Portable radar system10may manage all radar signal processing and only output target and obstacle information that does not require an in-depth understanding of radar function to incorporated into an application. In other words, processing circuitry of portable radar system10may output a signal to an external display device, such as mobile computing device12such that the signal includes an encoding scheme compatible with the external display device.

For example, portable radar system10may be mounted in a radome, or similar enclosure on a small aircraft that may not normally be capable of carrying a weather radar. Portable radar system10may output target and obstacle information to a situational awareness application executing on mobile computing device12. The situational awareness application may be used by pilots for navigation and other situational awareness. The developer for the pilot situational awareness application may incorporate the target information from portable radar system10to improve real-time pilot situational awareness by displaying nearby aircraft, UAVs, buildings, radio towers and other possible hazards. One or more portable radar systems10may be mounted as a network on a helicopter, for example, for situational awareness such as in reduced visibility environments, including when operating near terrain, buildings, bridges or other structures. In another example, portable radar system10may be installed on a UAV to output radar information to the UAV operator.

FIG. 1Bis a conceptual diagram illustrating an example transmit and receive beam of a portable radar system in accordance with one or more techniques of this disclosure. Radar transmit beam22A and first illumination direction24corresponds to transmit beam22and first illumination direction24depicted inFIG. 1A.

In some examples, azimuth scanning may be adjusted to permit three or more elevation positions without physically moving portable radar system10. In one example, the transmit beam22B, and associated receive beam28B, may be tilted up by one beamwidth. The example of transmit beam22A, and associated receive beam28A may be considered set to zero tilt. The example of transmit beam22C, and receive beam28C, may be tilted down by one beamwidth.

Transmit beam22A ofFIG. 1Bis an FMCW radar transmit beam that illuminates an area with a greater extent in a first illumination direction24(e.g., in azimuth) than in a second illumination direction26(e.g., in elevation). The second illumination direction26is substantially perpendicular to the first illumination direction24. In other words, transmit beam22A is a high-aspect ratio transmit beam that covers an AOI as determined by operator20(not shown inFIG. 1B). In some examples, the beamwidth of transmit beam22A in the first illumination direction24is greater than 65 degrees and less than eight degrees in the second illumination direction26. Transmit beam22A is fixed, in other words, portable radar system10does not scan transmit beam22A in the first illumination direction24or second illumination direction26. Operator20, for example, when using portable radar system10in a hand-held application may manually scan transmit beam22A. In some examples, portable radar system10and mobile computing device12(not shown inFIG. 1B) may communicate to determine the direction of transmit beam22A, such as a compass azimuth.

FIG. 1Bdepicts a receive beam28. Portable radar system10may digitally form receive beam28to scan across the FOR covered by transmit beam22A. In some examples, the receive beams may be monopulse receive beams. Processing circuitry of portable radar system10may use receive beam28to determine the position of a target and to track the target's motion. For example, track vehicles or personnel movements in a law enforcement or military application. Some examples of target detection information may include target detection information in three dimensions, the three dimensions may include position or location such as range, azimuth and elevation in relation to portable radar system10. Target location may be determined as grid coordinates, such as latitude and longitude, as well as elevation. Other target detection information may include distance, speed, elevation, acceleration, size or any combination of a target object at a specific direction with respect to portable radar system10.

The processing circuitry may be further operable to determine characteristics of ground-based features in the sub-area covered by receive beam28, such as structures, mountains, and the like. Some characteristics of ground-based features may include size, shape, location, and density. For example, a solid metal object may appear differently on the display than a wooden or similar object that has lower radar reflectivity. In other examples, portable radar system10may perform Doppler analysis of a target's movement. Details of the transmit and receive beams will be covered in more detail below, for example in relation toFIGS. 3B and 4.

In some examples, receive beam28is a first receive beam, and the processing circuitry is further operable to generate a second receive beam different from the first receive beam. Portable radar system10may be configured to use the second receive beam to simultaneously perform more than one function. In other words, the processing circuitry is further operable to generate a second receive beam different from the first receive beam, and the processing circuitry is operable to determine one or more characteristics of a second sub-area simultaneously with determining characteristics of the first sub-area. As one example, the first receive beam may track the movement and location of a first target and the processing circuitry may use the second receive beam to simultaneously perform Doppler analysis on a second target.

FIG. 2is a block diagram illustrating an example portable radar system in accordance with one or more techniques of this disclosure. Portable radar system10A, operator20, and mobile computing device12correspond to portable radar system10, operator20, and mobile computing device12depicted inFIG. 1A.

Example portable radar system10A ofFIG. 2includes antenna102A, processing circuitry30, memory device32, and communication interface34. Portable radar system10A communicates with mobile computing device12via communication link14. Communication link14includes the same features as described above in relation toFIG. 1A.

Antenna102A may include a substrate integrated waveguide (SIW) transmit (Tx) antenna126and SIW receiver (Rx) array122. Tx antenna126may output the high aspect ratio transmit beam22A as depicted inFIG. 1Babove. Rx array122may receive FMCW radar signals reflected from targets or objects. Tx antenna126and Rx array122will be discussed in more detail below, for example in relation toFIG. 3B.

Processing circuitry30may include radar transmitter electronics, radar receiver electronics and other processing circuitry. Processing circuitry30may communicate with memory device32. For example, processing circuitry30may execute software commands stored at memory device32. Processing circuitry30may also store data, such as target information at memory device32. Processing circuitry30may retrieve the data from memory device32for output via communication interface34or to perform calculations or other signal processing, described in more detail below.

In some examples, portable radar system10A may be configured to determine the location of portable radar system10A relative to mobile computing device12. In a hand-held example, portable radar system10A may be directly attached to mobile computing device12. In another example, portable radar system10A may be mounted at some distance from mobile computing device12. For example, in a law enforcement or border monitoring application, portable radar system10A may be mounted on a pole or on some other structure to cause transmit beam22A, depicted inFIG. 1B, to avoid being shadowed by geography or structures, such as a hill, trees, a building or similar obstacle. Increasing the height of portable radar system10A in some applications may extend the FOR.

Portable radar system10A may determine the relative location between portable radar system10A and mobile computing device12by, for example, a manual input from operator20, determining relative location by wireless means, or some other means of signal transfer. Processing circuitry30may determine the position of a detected target relative to portable radar system10A, such as a range and bearing. Processing circuitry30may then determine the position of the target relative to mobile computing device12by accounting for the relative location between portable radar system10A and mobile computing device12and including the relative location in the target information output to mobile computing device12. Alternatively, the application executing on mobile computing device12may determine the relative position between portable radar system10A and mobile computing device12and determine the target's position relative to mobile computing device12. In other words, in some examples, portable radar system10A may get the GPS location of mobile computing device12from the electronics within mobile computing device12, and uses the received GPS location to calculate coordinates for the target.

In some examples, portable radar system10A may determine the relative location between portable radar system10A and mobile computing device12during an initial phase of operation, such as when portable radar system10A connects to mobile computing device12, or during power on phase of portable radar system10A. In other examples, either the application executing on mobile computing device12or portable radar system10A may determine the relative location periodically during operation.

In some examples, portable radar system10A may be configured to receive other inputs from a computing device, such as mobile computing device12. Other inputs may include a global position system (GPS) input indicating the GPS location of mobile computing device12. Some examples of mobile computing device12may be able to determine a GPS location using built in GPS hardware, or by communicating to external GPS hardware. The GPS location may include, for example, a latitude, longitude and altitude of mobile computing device12. Portable radar system10A may be configured to receive the GPS location of mobile computing device12via communication interface34and incorporate the GPS location into the target information sent to mobile computing device12. For example, portable radar system10A may detect a UAV at a given range, bearing and altitude relative to portable radar system10A. Processing circuitry30may be configured to incorporate the GPS location of mobile computing device12into the target information. Processing circuitry30may output, for example, a target range, bearing and altitude relative to mobile computing device12. Alternatively, portable radar system10A may be configured to incorporate the GPS information to output a latitude, longitude and altitude of the UAV to mobile computing device12. As another example, portable radar system10A may output the UAV location relative to portable radar system10A and an application executing on mobile computing device12may determine the UAV location relative to mobile computing device12. The UAV location, in this example, may be depicted as range, bearing and altitude, map coordinates with altitude or other means of indicating location.

In some examples, portable radar system10A may be configured to operate as part of a network of detection devices. For example, two or more portable radar system10A may be configured to cover a perimeter of a vehicle, object or a position. Example applications may include a military encampment to warn the occupants of approaching vehicles, personnel and other targets. Another example may include a merchant ship, or other marine vessel transiting waters with narrow passages between hazards to navigation or with a danger of pirate attack. Existing marine radar systems, such as those with rotating antennae, may have difficulty detecting objects low in the water and close to the ship, such as shoals, icebergs or small, hostile vessels. A network of portable radar systems10may have advantages in detecting, displaying and warning of smaller, short range obstacles or targets.

In some examples, portable radar system10A may be part of a network that include other sensors, such as thermal imaging, audio detection, ultrasonic instruments and other sensors. A network of sensors, including portable radar system10A, may each connect to individual display devices, such as a respective mobile computing device12for each sensor. In other examples, the network of sensors may connect to a central control and display system, such as in a command center of a military encampment, the bridge of a ship or similar locations.

FIG. 3Ais a conceptual and assembly diagram illustrating an exploded view of an example radar system, which may be a component of a portable radar system in accordance with one or more techniques of this disclosure.FIG. 2Aillustrates an example radar system100which may include a SIW transmit and receive antennae and a protective cover or shield104. Radar system100may, for example, correspond to portable radar system10and10A as depicted inFIGS. 1A and 2above. In the example ofFIG. 3A, the radar system is implemented as a multi-layer printed circuit board (PCB)101that includes an SIW antenna layer102and one or more circuit layers103. Circuit layers103may include receiver chips108A-108D, analog-to-digital (A/D) converters106A-106D as well as other circuit elements. An analog-to-digital converter may also be called an “ADC.” In some examples, the antennae, and all RF components may be implemented on SIW antenna layer102. In the example of a millimeter wave radar system, SIW antenna layer102may include all the millimeter wave radar components and routing elements. In some examples, the one or more circuit layers103may include all the digital components, power supply and similar components, such as A/D converters. In some examples, the one or more circuit layers103configured with the digital components, power supply and similar components may be called the “core” board. In some examples radar system10, with the antenna, electronics, power supply and other components protected by a housing in a single, integrated package may be referred to as an integrated radar system.

Multi-layer PCB101may include circuits and components that implement a transmit array, radar transmitter electronics, a receive array, radar receiver electronics, processing circuitry, communication electronics, power conditioning and distribution, clock/timers and other circuitry and components. The circuits and components may be similar to processing circuitry30, described above in relation toFIG. 2. The processing circuitry may be configured to control the radar transmitter electronics and radar receiver electronics as well as process and identify radar targets and send notifications and information to users using the communication electronics. Processing circuitry may include, any one or more of a microprocessor, a controller, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a system on chip (SoC) or equivalent discrete or integrated logic circuitry. A processor may be integrated circuitry, i.e., integrated processing circuitry, and that the integrated processing circuitry may be realized as fixed hardware processing circuitry, programmable processing circuitry and/or a combination of both fixed and programmable processing circuitry.

The SIW antenna layer102may be electrically connected to circuit paths and components on one or more circuit layers103. SIW antenna layer102may be similar to antenna102A described above in relation toFIG. 2. In some examples, plated vias may provide connections between one or more circuit layers103, as well as to SIW antenna layer102. A via may be a plated or unplated hole that may be drilled, etched or otherwise formed between layers of multi-layer PCB101. A plated via may be plated with a conductive material to electrically connect layers. Some examples of conductive material may include copper, solder, conductive epoxy or other materials.

Protective shield104may cover and provide structural support for example radar system100. Protective shield104may be a molded plastic, stamped or formed sheet metal or other suitable material. Protective shield104may include a conductive coating in one or more areas to provide shielding for electromagnetic interference (EMI). Protective shield104may include penetrations for power, communication or other connections as well as be configured to securely mount radar system100. In the example ofFIG. 3A, the shape of the protective shield, SIW antenna layer102and circuit layers103is rectangular. However, in other examples the components of multi-layer printed circuit board PCB101and protective shield104may be round, octagonal or other shapes.

In operation, radar system100may provide digital electronic beam steering on received radar reflections by using, in part, phase shift commands within the components on one or more circuit layers103. The radar transmitter electronics, in signal communication with the radar transmit antenna, are configured to output, e.g., transmit, radar signals that are a fixed, wide beam illumination as described above in relation toFIGS. 1A, 1B and 2. The radar receiver electronics in signal communication with the radar receive antenna search the reflected radar signals by a “pencil beam” monopulse receive pattern that scans within the illuminated transmit area, which may be similar to receive beam28depicted inFIG. 1Band main receive lobe410B depicted inFIG. 9B. In other words, radar system100, in this example, is an FMCW dual antenna radar system that provides wide beam illumination on transmit and then an electronically scanned receive beam that searches within the wide transmit illumination area, or FOR.

The FMCW radar signals may provide very fine range resolution and allows very low receiver bandwidth and low data rates when compared to other examples of radar signals. This includes resolution in all three dimensions. In other words, radar system100may locate the X, Y and Z position of possible targets. Locating the position of a target in all three dimensions covered by the transmit beam, may have advantages, such as to differentiate between a target on the ground and a target above the ground.

Executing the digital electronic beam steering at baseband frequencies provides the advantage of reduced cost and complexity because of fewer radio frequency (RF) components. In some examples, the digital electronic beam steering according to the techniques of this disclosure may also be capable of receiving multiple simultaneous beams.

In one example, radar system100may use a heterodyne FMCW radar with a 16 MHz first intermediate frequency (IF) before down conversion to a baseband between 1 KHz and 2 MHz. Radar system100may apply the 16 MHz offset using a dual direct digital synthesis (DDS) at the transmit array. A heterodyne system may provide advantages over other FMCW radars that use a homodyne receiver to directly convert RF signals to baseband near zero frequency. Radar system100may include components with a passband that includes 16 MHz. These components may also provide simultaneous down conversion to base band, I/Q channel formation and four-bit phase shift. By using multi-function components along with frequency down conversion, radar system100may achieve performance advantages over a standard homodyne receiver, even a homodyne receiver that may use an I/Q mixer on receive. A few examples include I/Q accuracy (true 90 degree offset), four-bit phase shift, fine range and elevation resolution, low receiver bandwidth, low data rates, small size, light weight, low power consumption, integrated package. In other words, the transmit array, the receive array, the radar transmitter electronics, radar receiver electronics and the processing circuitry comprise a single, integrated package. Additionally, a radar system according to this disclosure may be configured for easy retrofit of existing platforms.

FIG. 3Bis a conceptual diagram illustrating the transmission, receive and communication antennae of an example radar system in accordance with one or more techniques of this disclosure.FIG. 3Billustrates a more detailed view of the radiating and receiving portion of SIW antenna layer102shown inFIG. 3A. SIW antenna layer102may include a communication antenna120, an SIW receiver (Rx) array122, an isolation area124and an SIW transmit (Tx) antenna126. SIW Rx array122may include one or more radar receiver antenna subarrays132A-132D. Each subarray may include an SIW Rx array element200. In the example ofFIG. 3B, each subarray132A-132D contains eight SIW antenna devices. For clarity,FIG. 3Bonly shows SIW Rx array element200with a reference number. SIW Rx array element200may also be referred to as a slotted waveguide antenna device. Therefore, SIW Rx array122may be considered a slotted waveguide radar receive antenna. SIW Tx antenna126may be considered a slotted waveguide radar transmit antenna.

SIW Tx antenna126(or slotted waveguide radar transmit antenna) may be in signal communication with the radar transmitter electronics. In some examples, SIW Tx antenna126may be referred to as a radar transmit array that includes a plurality of transmit antenna elements. The radar transmitter electronics, in conjunction with the slotted waveguide radar transmit antenna, may be configured to output radar signals to a predetermined coverage area. The predetermined coverage area may be similar to the FOR depicted inFIG. 1B. The terms radar transmit electronics and radar transmitter electronics may be used interchangeably in this disclosure.

SIW Rx array122(or slotted waveguide radar receive antenna) may be in signal communication with radar receiver electronics. The radar receiver electronics may include digital beam forming circuitry configured to receive radar reflections corresponding to the outputted radar signals from the radar receive antenna. The outputted radar signals may reflect off objects present in the predetermined coverage area. The radar receiver electronics may send information to the processing circuitry about the reflected signals from objects present in the FOR, or predetermined coverage area. The processing circuitry may be configured to generate a notification in response to a radar reflection received from the first coverage area.

In the example ofFIG. 3B, SIW Rx array122includes 16 columns of SIW Rx array element200, separated into a top and bottom set of columns. SIW Rx array122is further separated into a left and right set of columns of SIW Rx array element200. The result is SIW Rx array122separated into four parts, i.e. subarrays132A-132D (collectively subarrays132). Each subarray132includes eight SIW Rx array element200, which may be considered waveguide “sticks.” The configuration of the example SIW Rx array122allows four quadrants with eight waveguide sticks (SIW Rx array element200) in each. Portable radar system10uses the four quadrants (subarrays132) for monopulse angle measurement. In other words, the four subarrays132allow portable radar system10to form a monopulse azimuth beam (AZ beam), an elevation beam (EL beam) and a sum beam.

Isolation area124may be used to isolate the outputted radar signals coming from SIW Tx antenna126from interfering with SIW Rx array122. Isolation area124may have dimensions and be composed of material to ensure proper function of radar system100. For example, isolation area124may be a structure such as an electronic band gap structure or an absorptive structure. The dimensions and/or material may vary depending on the operating frequency of radar system100.

Communication antenna120may be configured to transmit and receive signals used to communicate using a variety of techniques, as described above in relation toFIGS. 1A, 1B and 2. Some examples may include communication over a wireless local area network (WLAN) using Wi-Fi, Bluetooth, and similar examples. In some examples, radar system100may communicate using either or both wireless and wired communication, as described above. Communication antenna120may be communicatively coupled to electronic communication circuitry within radar system100configured to receive information from processing circuitry within radar system100. For example, the electronic communication circuitry may be part of multi-layer PCB101. The electronic communication circuitry, in conjunction with Communication antenna120may be configured to communicate with display units or other types of units external to radar system100. Some examples of external display units may include mobile computing device12, tablet computers or hand-held mobile devices, as described above.

FIG. 4Ais a conceptual and schematic block diagram illustrating an example radar system using a slot waveguide antenna array system in accordance with one or more techniques of this disclosure.FIG. 4Adepicts SIW Rx array element200and SIW Tx array202, which function similarly to the SIW Rx array element200of SIW Rx array122and SIW Tx antenna126as shown inFIG. 3B. Receiver IC206and ADCs212A-212D may be similar to the receiver chip108A-108D and A/D converters106A-106D shown inFIG. 3A. The features of receiver IC206will be described in further detail below. An example component that may perform some of the features of receiver IC206may include the AD9670 Octal Ultrasound Receiver.

Rx mixer204may receive inputs from SIW Rx array element200and reference signal218from digital synthesizer transmitter216to down-convert the reflected radar signals received by SIW Rx array element200. Rx mixer204may output the downconverted radar receive signal to a respective receiver integrated circuit (IC)206for a respective receive channel. Receiver IC206may output the respective signals for the respective receive channel to a respective ADC, such as ADC212C as shown in the example ofFIG. 4A. In some examples ADC212A-212D may be implemented by an eight-channel ADC integrated circuit, i.e. include additional ADC channels212E-212H (not shown inFIG. 4A).

Note thatFIG. 4Adepicts a single SIW Rx array element200and a single mixer200, however, referring toFIG. 3B, each subarray132has eight SIW Rx array elements200and eight mixers204. In some examples, each subarray132may output received signals to two four-channel mixer ICs205. In some examples, a may also include buffer amplifiers, low noise amplifiers and other circuit elements not shown inFIG. 4Afor clarity. An example of a four-channel mixer may include the ADF5904 from Analog Devices. In other words, portable radar system10, with SIW Rx array122may include thirty-two SIW Rx array elements200, thirty-two mixers204on sixteen four-channel mixer integrated circuits205, that output to four eight-channel ADC integrated circuits.

FPGA processor and controller214(“FPGA214”) may receive the digitized signals from the receive channel ADCs212A-212C. FPGA214may perform the functions of, target detection processing and analysis and send target information to the external communication system to be further sent to one or more display devices. FPGA214may also control the radar transmitter electronics, which are configured to output radar signals in conjunction with the SIW radar transmit array202. Radar transmitter electronics may include digital synthesizer transmitter216. In some examples FPGA214may be part of a multi-processor system on chip (MPSoC) processor architecture. Some examples of MPSoC processors provide both parallel processing to form multiple receive beams as well as include several advanced reduced instruction set (RISC) machine (ARM) or similar processors that can provide post beam forming processing.

FPGA214may also control the radar receiver electronics which may include Rx mixer204, the receiver integrated circuits (IC)206, summing amplifier210and ADCs212A-212D. The radar receiver electronics may include digital beam forming circuitry configured to receive radar reflections corresponding to the outputted radar signals, and to send signals associated with the radar reflections to FPGA214. SIW Rx array element200, acts as a radar receive antenna to collect radar reflections impinging on the surface of its slot layer. SIW Rx array element200may be a single SIW Rx array element200in a subarray132A within the SIW Rx array122, as depicted inFIG. 3B. The terms radar receiver electronics and radar receive electronics may be used interchangeably in this disclosure.

As described above in relation toFIGS. 4 and 6, radar receiver electronics that include a four-channel mixer IC, such as four-channel mixer IC205, may provide advantages such as simplified signal routing, which also may help ensure signals are processed in phase without complex compensation. Some examples of four-channel mixer IC205may also include LNAs, output amplifiers, signal buffers and other components, further simplifying implementation of the radar receiver electronics.

FPGA214and digital synthesizer transmitter216may include circuitry that converts received radar signals to a lower frequency for further processing. Further processing may include beam steering, target detection and location as well as other functions. Other types of functions performed by FPGA214and digital synthesizer transmitter216may include in-phase and quadrature processing (I and Q), filtering, frequency, phase and amplitude control, modulation, direct digital synthesis (DDS) and other functions. The digital beam forming circuitry may be configured to operate in the ultrasonic frequency range. The digital beam forming as described above may provide advantages over using heterodyne mixing for beam forming on transmit or receive. In some examples, the radar system of this disclosure may use heterodyne single sideband image reject mixer to offset the VCO signal (e.g. 24 GHz) with the required offset (e.g. 16 MHz) and suppress one of two possible signals that would come from a mixer (e.g. 24 GHz+/−16 MHz) so that only the desired signal (e.g. 24 GHz+16 MHz) is passed.

The digital beam forming circuitry may process the receive signals into monopulse beams that may be used for accurate navigation as well as detection and tracking of targets, such as vehicles, people, unmanned aerial vehicles and the like. The monopulse beams may be used to determine an azimuth, elevation and range of the target from the radar system. As depicted inFIGS. 1A, 1B and 3A, radar system10,10A and100may perform monopulse analysis for each receive beam, such as receive beam28, which may facilitate tracking multiple objects within the transmit beam22FOR. Monopulse receive beams may provide accurate angle and distance measurements as well as tracking of objects within the sub-areas covered by a receive beam.

A radar system according to the techniques of this disclosure, may have advantages over other radar systems because the configuration may result in reduced computing requirements. For example, FPGA214may not need to computer the electronic beam steering because beam steering on receive is achieved on the receive array using a downconverter and phase shifter (see downconverter and phase shifter352described below). The beam steering occurs at IF frequency and not at an RF frequency, e.g. 24 GHz. The phase shift commands for the steering are issued by FPGA214, or MPSoC (e.g. FPGA plus ARM, described above) so that the beam is steered as desired. FPGA214may have a simplified task of computing range bin fast Fourier transforms (FFT). The elevation beam switching, described above in relation toFIG. 1B, also occurs on the face of the array with external components and may not need electronic beamforming processing, just the range bin FFT. This simplified implementation may provide advantages in cost, reliability, size and power consumption.

FIG. 4Bis block diagram of an example a four-channel mixer IC. Four-channel mixer IC205may include buffer amplifiers209A-209D, low noise amplifiers207A-207D and mixers204A-204D. In some examples, four-channel mixer IC205may include other circuit elements, such as circuit protection elements, clock input, circuit test input and output, and similar components not shown inFIG. 4B. As described above in relation toFIG. 4A, an example of a four-channel mixer may include the ADF5904 from Analog Devices.

The output of each SIW Rx array elements200may connect to an input of a low noise amplifier (LNA), such as LNA207A. In some examples, the input to each LNA may be preceded by a balun (not shown inFIG. 4B), which is used to connect a differential, balanced RF functional block, such as SIW Rx array elements200in some examples, to a single-ended, ground-referenced load, such as LNAs207A-207D.

The output of each LNA207A-207D connects to mixer204A-204D, respectively. Each mixer204A-204D may also receive as an input the signal from the local oscillator network via LO input130to four-channel mixer IC205. Each mixer2014A-204D functions as described above and below for mixer204. In examples where the local oscillator input is a differential RF signal, the LO input130may also include a balun (not shown inFIG. 4B).

The output of each mixer204A-204D may connect to the input of buffers209A-209B, respectively. The outputs of buffers209A-209D may connect to the phase shifting block, as described in relation toFIGS. 4-7. Four-channel mixer IC205, may provide advantages such as simplified signal routing, which also may help ensure signals are processed in phase without complex compensation.

FIG. 5is a conceptual and schematic block diagram of an example radar receive channel and radar transmitter electronics in accordance with one or more techniques of this disclosure. The example diagram ofFIG. 5depicts a single receive channel and an example implementation of superheterodyne up and down conversion between RF frequencies and other frequencies. Other receive channels that may be part of radar system are not shown inFIG. 5for clarity.

FIG. 5includes additional details of portions of radar system100using a slot waveguide antenna array shown inFIG. 4A.FIG. 5may include SIW Rx array element200, SIW Tx array202and Rx mixer204as shown inFIG. 4A. FPGA214, digital synthesizer transmitter216and receiver IC206depicted inFIG. 4Amay include some of the separate components depicted inFIG. 5.FIG. 5depicts VCO300, local oscillator (LO) feed network302and other receive channels304, along with in-phase and quadrature (I and Q) unit306, low pass filters (LPF)308and312and analog to digital converters310and314. Other radar electronics may include FPGA214A, synthesizer322, 128 MHz master clock324, frequency dividers326, dual digital direct synthesis (DDS) unit328, I/Q single side band (SSB) mixer330, and amplifier332. Also, communication system320may receive information from FPGA214A. As described above, mixer204may be implemented by a four-channel mixer IC, e.g. four-channel mixer IC205, which may provide advantages such as simplified routing and additional components such as LNAs for each channel. For example, four-channel mixer IC205may include LNA207between SIW Rx Array200and Rx Mixer204, for each channel, as well as an input for LO Feed network302.

The radar receiver electronics depicted inFIG. 5may down-convert received radar signal from SIW Rx array element200to an intermediate frequency (IF) 16 MHz (340) and to lower frequencies for further processing, which may include receive beam steering. The radar transmitter electronics may transmit RF energy with a wide azimuth and narrow elevation through transmit (Tx) array202. In other examples, the 16 MHz IF may be 12 MHz or some other intermediate frequency.

VCO300, as shown in the example ofFIG. 5, generates a 24 GHz signal which is distributed to the LO feed network302and further to Rx mixer204. LO feed network302may function, for example, as an eight-way power divider. As described above, in some examples LO feed network302may output to LO input130of multiple four-channel mixer IC205. Each four-channel mixer IC205may provide a four-way internal LO distribution to each of the four mixers as well as an LO buffer for each receive channel. VCO300also distributes 24 GHz to I/Q SSB mixer330. VCO300may receive input from synthesizer322. 24 GHZ is shown as one example. In other examples VCO300may generate other frequencies, such as 13 GHz.

LO Feed network302may output the 24.0 GHz LO signal to other receive channels304as well as Rx mixer204, which functions the same as Rx mixer204shown inFIG. 4A. In the example ofFIG. 5, Rx mixer204converts the 24.016 GHz reflected radar signal from SIW Rx array element200to an intermediate frequency (IF) of 16 MHz (340). These frequency values are only for illustration. Radar system100may also use other frequencies. Rx mixer204may output the IF of 16 MHz (340) to I and Q unit306.

Synthesizer322may utilize a method of changing the division ratio within a digital PLL synthesizer to provide frequencies that are not integral multiples of the comparison frequency. A divider may take a fractional division ratio rather than an integer ratio by alternating between division ratios. One example may include a fractional N synthesizer that uses the basic digital PLL loop. Analog Devices component ADF4159, a direct modulation fractional-N frequency synthesizer, is one example of a fractional N synthesizer. However, in some examples fractional N synthesizers may generate spurious signals that appear as false targets in the receiver. Other examples of synthesizer322may include a direct digital synthesizer that may have advantages over a fractional N synthesizer.

Frequency synthesis may use various forms of Direct Digital Synthesizer, Phase Lock Loop, frequency multiplier and other methods. Synthesizer322will generate a linear FMCW waveform and may receive control and other inputs from FPGA214A.

I and Q unit306may include a phase shift function along with the in-phase and quadrature function. A monopulse radar may need to get information both from the real and imaginary portions of the returned radar signal. I and Q unit306may provide a representation of the returned radar signal at the intermediate frequency (IF) of 16 MHz, as shown inFIG. 5. These frequencies listed inFIG. 5are just for illustration. Other frequencies may also be used. The quadrature down conversion may divide the 128 MHz oscillator signal by eight, e.g. 8×16 MHz=128 MHz. Terms for 128 MHz master clock324may include reference oscillator, 128 MHz oscillator and 128 MHz clock. These terms may be used interchangeably in this disclosure.

I and Q unit306may perform two functions simultaneously. First, I and Q unit306may divide 128 MHz clock signal324by eight and provide a four-bit phase shift with digital control. At the same time as the four-bit phase shift, I and Q unit306may form the in-phase (I) and quadrature (Q) signal portions and downconvert the 16 MHz IF frequency to a base band338between 1 kHz and 2 MHz. The I and Q signal portions may also be called the “I” channel and “Q” channel. The output signal from I and Q unit306passes through LPF308and312and ADCs310and314may digitize each portion of the returned signal. ADCs310and314may receive input from frequency dividers326. Both frequency dividers326and I and Q unit306may receive a 128 MHz clock signal from 128 MHz master clock324. Frequency dividers326may output a signal to ADCs310and314.

FPGA214A may receive the separate I and Q signals from each receiver channel. FPGA214A may combine and process the signals to determine the 3D position of obstacles within the radar coverage area, as shown inFIG. 1A. FPGA214A may process obstacle information, including size, height, rate of closure and other information and send to Communication system320. Communication system320may further send obstacle information of one or more display devices. One possible example of FPGA214A may include the Xilinx XC7k70t 7-series FPGA.

Radar transmitter electronics may include dual DDS328and I/Q SSB mixer330. Dual DDS328may receive commands and control inputs from FPGA214A and output a 16 MHz intermediate frequency I signal334and Q signal336to I/Q SSB mixer330. An example dual DDS may include the Analog Devices AD9958.

I/Q SSB mixer330may receive the signals from dual DDS328, as well as a 24 GHz signal from VCO300. I/Q SSB mixer330may output radar signals to amplifier332and further to SIW transmit array202. One example of amplifier332may include the HMC863 from Analog Devices. SIW transmit array202may output the radar signals in the prescribed pattern. Any reflected radar signals may impinge on SIW Rx array element200and be conducted to the FPGA for processing.

FIG. 6is a conceptual block diagram of portions of an example receive module illustrating multiple channels that may be part of radar receive electronics in accordance with one or more techniques of this disclosure.FIG. 6illustrates example components and techniques to process received radar signals from a portion of SIW receiver array122as shown inFIG. 3B. The example ofFIG. 6depicts other details of the functions ofFIG. 4andFIG. 5that include an example radar receiver subarray132A, such as that shown inFIG. 3B. A complete, radar system may use one or more sets of the components shown inFIG. 6. For example, a radar system that uses four radar receiver subarrays may use four sets of components as shown inFIG. 6to achieve the 32 channels shown inFIG. 3B.

Receive module350may include radar receiver antenna subarray132A, VCO300, an Rx mixer204A-204H for each channel, an octal downconverter and phase shifter352, a summing operational amplifier (opamp) and LPF for both in-phase354(“I”) and quadrature356(“Q”) signals, a dual channel low voltage differential signaling (LVDS) unit358, FPGA clock dividers360and voltage regulators362. The components depicted in receive module350may be mounted and inter-connected on multi-layer PCB101that includes a, SIW antenna layer102and one or more circuit layers103, shown inFIG. 3A.

The example ofFIG. 6depicts radar receiver antenna subarray132A to include eight SIW Rx array elements200A-200H. In other examples, radar receiver subarray132A may include than eight SIW Rx array elements. Each SIW Rx array element200A-200H connects to a respective Rx mixer204A-204H. Each Rx mixer204A-204H for each of the eight channels depicted in receive module350also receive a 24 GHz LO signal from VCO300. The Rx mixers down-convert the reflected radar signal received by the SIW Rx array element for each channel and send the input to downconverter and phase shifter352. The signal path for each channel may include components other than Rx mixers204A-204H, as depicted byFIGS. 4, 5and below inFIG. 7.

The example ofFIG. 6depicts an Rx mixer204for each channel. As described above in relation toFIG. 4A, other examples may use a four-channel mixer IC, e.g.205A and205B, rather than a single mixer for each channel, which may include additional components, such as low noise amplifier, not shown inFIG. 6. Example four-channel mixer components may include the ADF5904 from Analog Devices. A four-channel mixer IC, such as205A and205B, may have advantages over individual mixers and other components. For example, the LO network, e.g. LO feed network302depicted inFIG. 5may be simplified because some examples of a four-channel mixer IC205may provide internal connections for LO distribution. LO network302may feed eight four-channel mixer ICs205rather than individual components.

As described above, mixer components may have performance advantages when placed in the middle of the SIW subarrays so that the path lengths between each subarray and the four-channel receiver chip is equal length. For example, this may allow the signal from VCO300to arrive at the same time and in the same phase for each receiver channel.

Downconverter and phase shifter352may perform a variety of functions for each of the eight channels. Some examples may include preamplification, harmonic rejection, anti-alias filtering, I/Q demodulation and phase rotation, digital demodulation and decimation as well as conversion to digital signals through ADC. One possible example component to perform at least some of the functions of downconverter and phase shifter352may include the Analog Devices AD9670 Octal Ultrasound Analog Front End (AFE) Receiver. Downconverter and phase shifter352may receive a 128 MHz clock input from 128 MHz master clock324. Downconverter and phase shifter352may output an in-phase “I” signal for each channel to a set of summing opamp and low pass filters for each channel, depicted as a single unit354in the example of receive module350. Similarly, Downconverter and phase shifter352may output a quadrature “Q” signal for each channel to a set of summing opamp and low pass filters for each channel, depicted as a single unit356.

LVDS unit358may receive the “I” and “Q” inputs from summing opamp and low pass filters354and356as well as an input from FPGA clock dividers360. LVDS unit358may operate under the LVDS, or TIA/EIA-644 technical standard to sample the input signals and perform analog-to-digital conversion. Example components that may perform one or more functions of LVDS unit358may include Analog Devices AD7357 or AD7356 differential input ADC components. LVDS unit358may output the digitized “I” and “Q” signals for further processing, such as beam forming, obstacle identification and other functions as needed by a portable radar system, in accordance with one or more techniques of this disclosure.

Receive module350may also include voltage regulators362. Voltage regulators362may provide regulated power supplies to the components of receive module350. For example, LVDS unit358may require an input voltage of 2.5V while downconverter and phase shifter352may require an input voltage of 3.0 V. Voltage regulators362may supply power for proper operation of each component in receive module350.

FIG. 7is a conceptual and schematic diagram depicting additional details of a portion of the radar receive electronics that may be included in a radar system.FIG. 7depicts a four channel of example of radar receive electronics. In the example SIW receiver array122as shown inFIG. 3B, the set of electronics depicted inFIG. 7would be repeated for the total number of channels in the receive array. Therefore, subarray132A, with eight channels would connect to two examples ofFIG. 7.FIG. 7retains the same numbers for components where components inFIG. 7perform the same function as in other figures. For example, SIW Rx array elements200A-200D and 128 MHz master clock324perform the same function as those components shown inFIG. 6.

FIG. 7illustrates some of the additional components that may be included in the radar receiver electronics, which may be mounted and interconnected on multi-layer PCB101.FIG. 7depicts LO feed network302A, Rx mixers204A-204D, SIW Rx array elements200A-200D, intermediate frequency (IF) LNA and high pass filter (HPF)370, downconverter and phase shifter352, summing opamp and LPF354and356for the “I” and “Q” signals, “I” ADC314A and “Q” ADC310A. Also shown in the example of downconverter and phase shifter352is quadrature divider372and serial data in (SDI) controller374.

LO feed network302A may deliver a 24 GHz oscillator signal to Rx mixers204A-204D. LO feed network302A may receive as input the 24 GHz LO signal from a VCO, such as VCO300, not shown inFIG. 7, but shown inFIGS. 5 and 6. The example ofFIG. 7depicts LO feed network302A configured so each path length from the LO is the same length. This may ensure the signal from the LO, such as a VCO, arrives at each Rx mixer204A-204D at the same time and with the same phase.

Rx mixers204A-204D function the same as described above by receiving and downconverting the reflected radar signals from SIW Rx array elements200A-200D. Rx mixers204A-204D output the downconverted signals to the respective channels of IF LNA and HPF370(referred to as “LNA370” for clarity). LNA370outputs each channel to a respective channel of downconverter and phase shifter352. In the example of an FMCW radar, the high pass filter may set the frequency response of the receiver. In one example, a high pass filter may be used to set the IF response to have a 40 dB per decade response over a frequency range of about 1 KHz to 2 MHz. This function may exactly offset the propagation losses as a function of range.

Downconverter and phase shifter352functions the same as described above. Also depicted inFIG. 7is quadrature divider372, which may be part of the phase shift function that creates the “Q” output for the monopulse radar receive signals. SDI controller374may help manage the data flow to the summing op amps.

Summing opamp and LPF354and356may act as summing amplifier for the “I” and “Q” signals respectively. Summing opamp and LPF354and356may combine the signals from the various receive channels for further processing. The LPF portion may remove the upper sideband from the I/Q mixing function. In some examples, not shown inFIG. 7, the filtering function before “I” ADC314A and “Q” ADC310A may include an HPF followed by a LPF or anti-aliasing filter. The filtering function of the LPF or anti-aliasing filter before the ADCs is to stop all gain above the maximum frequency of the HPF. In some examples, the HPF maximum frequency may be 2 MHz.

“I” ADC314A and “Q” ADC310A perform the same function for the I and Q ADCs described above. “I” ADC314A and “Q” ADC310A digitize the four channels of downconverted and filtered radar receive channels and output the digitized signals for further processing, as described above.

FIG. 8is a conceptual diagram illustrating an example radar transmission pattern for a radar system, in accordance with one or more techniques of this disclosure.FIG. 8includes an example transmit antenna400, a wide azimuth, narrow elevation main transmission beam404and sidelobes402. In other words, the transmission beam404illuminates an area to a greater extent in a first illumination direction, such as azimuth, than in a second direction, such as elevation. The radar transmitter electronics, in conjunction with the radar transmit antenna400, may be configured to output radar signals comprising a transmitted radar beamwidth of less than eight degrees in elevation and at least 65 degrees in azimuth. In some examples, the beamwidth may be at least 80 degrees in azimuth. Radar transmit antenna400may function in a similar manner to SIW transmit array202shown inFIG. 4Aand SIW Tx antenna126shown inFIG. 3B. The example SIW transmit pattern may include low elevation sidelobes, which may have the advantages of preventing false alerts and erroneous detections.

FIGS. 9A-9Care conceptual diagrams illustrating example radar receive pattern for a portable radar system, in accordance with one or more techniques of this disclosure.FIG. 9Aincludes an example slotted waveguide radar receive antenna122A, which is similar to the SIW Rx array122shown inFIG. 3B.FIG. 9Bdepicts an example receive radar pattern with main receive lobe410B and side lobes412B.FIG. 9Cdepicts a side view of an example radar receive pattern including main lobe410C, side lobes412C and rear lobe414. The beam steering radar receive pattern, may be controlled by the digital beam forming circuitry, described above. The radar receive pattern may include a target detection radar imaging resolution of at least three square meters at a range of 100 meters. The receive pattern may include a radar range resolution of at least 1 meter and radar angular resolution is no more than one and one-half degrees in azimuth and elevation.

FIG. 10is a graph illustrating an example radar receive pattern for a portable radar system, in accordance with one or more techniques of this disclosure. The graph ofFIG. 10depicts a radar receive pattern similar to the patterns shown inFIGS. 9B-9C.FIG. 10depicts main lobe410D and side lobes412D.