Abstract: A method, apparatus and computer program product are configured to dynamically augment ionospheric correction data. A method receives, from a requesting device, a request for grid layout data, where the grid layout data is associated with one or more geographical areas experiencing atmospheric delay incurred with a satellite-based positioning technique. The method transmits, in response to the request for the grid layout data, a grid layout definition message comprising a grid layout definition associated with the grid layout data associated with the one or more geographical areas. The method generates correction data based in part on the grid layout data, where the correction data is configured to correct the atmospheric delay incurred with the satellite-based positioning technique. The method also generates correction messages comprising at least a portion of the correction data and transmits the correction messages to the requesting device based on a dynamic correction data update rate.

Abstract: A wearable device includes a carrier element, a wearable element, a SIP (System-In-Package) IC (Integrated Circuit), a first antenna element, and a second antenna element. The wearable element is connected to the carrier element. The SIP IC includes a first transceiver and a second transceiver. The SIP IC is disposed on the carrier element. The first antenna element is coupled to the first transceiver. The first antenna element is integrated with the SIP IC. The second antenna element is coupled to the second transceiver. The second antenna element is integrated with the carrier element.

Abstract: A calibration circuit and a calibration method for a phase shifter, a phase-shift circuit, a radio frequency transmitting circuit, a radio frequency receiving circuit, a radar sensor and an electronic device are provided. The calibration circuit for the phase shifter includes a phase acquisition circuit and a phase calibration circuit, the phase acquisition circuit coupled to the phase shifter is configured to modulate a radio frequency sample signal acquired from the phase shifter using a first baseband signal, down-convert the modulation signal to obtain a second baseband signal containing an actual phase; the phase calibration circuit coupled to the phase acquisition circuit is configured to acquire the actual phase in the second baseband signal, determine calibration phase information according to a phase deviation between the actual phase and a preset phase-shift phase, generate a phase-shift control signal according to calibration phase information and transmit it to the phase shifter.

Abstract: An antenna board capable of transmitting and receiving millimeter wave signals is provided and the antenna board and a power board are respectively provided on both sides of a heat dissipation support, a radar interface terminal is configured to be electrically connected to the power board, and a housing is provided for accommodating and fixing components such as the power board, so that the millimeter wave car-reversing radar can not only penetrate components such as a bumper, and even if the millimeter wave car-reversing radar is mounted on a car frame, detection and car reversing and parking prompt reminding functions of the radar are likewise not affected.

Abstract: A mobile device having array antenna can be used to communicate with Earth orbiting satellites and base stations on the ground. The display screen of the mobile device has an array antenna capable of transmitting and receiving radio frequency (RF) signals in the range of 0.6 GigaHertz (GHz) to 100 GHz. The configuration of the array antenna, including the number of arrays and the dimension of the arrays, is software programmable by activating and deactivating antenna elements for multiple beams and their beam characteristics.

Abstract: A vehicle radar sensor unit (2) having an antenna arrangement (3), a transceiver arrangement (4a, 4b, 4c, 4d) and a processing unit (6). The antenna arrangement (3) includes at least one transmitter array antenna (7) and at least two receiver antennas (24, 25, 26; 27, 28, 29; 30, 31, 32; 33, 34, 35), where each transmitter array antenna (7) have at least two sub-antennas (12, 13, 14, 15, 16, 17, 18, 19) that are vertically spaced from each other, where each sub-antenna (12, 13, 14, 15, 16, 17, 18, 19) have at least one antenna element (20, 21), and where each receiver antenna (24, 25, 26; 27, 28, 29; 30, 31, 32; 33, 34, 35) have a plurality of series fed antenna elements (22, 23) formed in a vertically extending column.

Abstract: The millimeter-wave radar includes a radome, an antenna board, a metal middle frame, a main control board and a base which are sequentially arranged. An image acquisition module is provided on one side of the main control board facing the radome. The antenna board is provided with a radar transceiver control module and is electrically connected to the main control board. The metal middle frame is provided with a notch through which the image acquisition module passes. The radome is made of a material through which radar waves emitted by the antenna board can pass; the radome is connected to the base; the main control board, the antenna board and the metal middle frame are located in a space enclosed by the radome and the base; and the radome is provided with a through-hole which communicates with the notch so that the image acquisition module extends outside of the through-hole.

Abstract: A radar sensor for reception of radar waves. The radar sensor includes at least one control unit and at least one circuit board. The at least one circuit board includes a substrate and a structure that is arranged on the substrate and has a multiplicity of metallization structures. The radar sensor is configured to be arranged on a radome in such a manner that the substrate is arranged on a side facing away from the radome and the structure is arranged between the radome and the substrate. The at least one control unit is arranged on a side of the substrate facing away from the radome and is in communicative connection with the at least one circuit board. At least one opening is made in the structure and only ambient medium is present between the radome and the at least one opening.

Abstract: An antenna system includes a multilayer circuit board, a first radiation element, a second radiation element, a first ground plane, a first feeding element, a second feeding element, a second ground plane, and a plurality of conductive via elements. The multilayer circuit board includes a first layer and a second layer. The first radiation element has a first slot. The second radiation element has a second slot. The second radiation element is adjacent to the first radiation element. The first radiation element, the second radiation element, and the first ground plane are disposed on the first layer. The first feeding element extends across the first slot. The second feeding element extends across the second slot. The first feeding element, the second feeding element, and the second ground plane are disposed on the second layer. The conductive via elements couple the second ground plane to the first ground plane.

Abstract: The present disclosure presents a front-end assembly (100) for an antenna array. The front-end assembly (100) comprises at least four front-end circuits (200), each operatively connectable to one single antenna element (35) of the antenna array (30) and interconnected to form a matrix structure comprising at least two column signal lines (110) and at least two row signal lines (120). Each front-end circuit (200) comprises a first mixer circuit (210) and a second mixer circuit (220). Said interconnection is formed by at least two first mixer circuits (210) being operatively connected to each other in parallel in each column signal line (110) and at least two second mixer circuits (220) being operatively connected to each other in parallel in each row signal line (120). Further to this, an antenna front-end assembly (10), an integrated circuit, a network node, a wireless device and a method for controlling the front end assembly (100) are presented.

Abstract: An RF front-end module for a millimeter-wave radar is provided. By placing at least one receiving channel and at least one transmitting channel between two metal plates, both RF-connected to the chip and surrounded by several metalized through holes, and arranging several antenna slot gaps corresponding to each receiving and transmitting channel on the upper metal plate, the RF front-end module of the present disclosure offers wider beamwidth, larger reflection coefficient bandwidth, symmetrical radiation patterns, and a larger field of view, enabling advantages such as stable matching, efficient transmission, accurate targeting, and broad monitoring areas, especially suitable for high-precision, wide-angle radar antenna applications. Existing patch microstrip antennas are limited by size and simple structure and cannot achieve these effects. It's difficult to design a broadside antenna radar module with wide bandwidth, high performance, and a wide field of view using conventional patch microstrip antennas.

Abstract: An apparatus includes a clock signal input, a sampling circuit, and an estimation circuit. The clock signal input receives N time measurements. A time measurement denotes a respective portion of a given cycle of a clock signal. The sampling circuit is to generate a first sampled window based upon a first time measurement and a first previous time measurement received m time measurements earlier than the first time measurement. The sampling circuit is to generate a second sampled window based upon a second time measurement and a second previous time measurement received m time measurements earlier than the second time measurement. The estimation circuit is to estimate the frequency or period of the clock signal based upon the first sampled window and the second sampled window.

Abstract: An optical sensing device includes: an optical sensor provided on a substrate and configured to radiate light to the outside of a housing through an optical window, and to receive the light that returns to the housing through the optical window; and a heat conductive member connected to the optical sensor and the housing and configured to conduct heat from the optical sensor to the housing.

Abstract: The embodiments relate to a radar control device and method. Specifically, a radar control device according to the embodiments may include an antenna device comprising a non-uniform linear array (NLA) antennas spaced apart according to a predetermined ratio, a first uniform linear array (ULA) antenna generated by being spaced apart by a first interval based on the NLA antenna, and a second ULA antenna generated by being spaced apart by a second interval based on the NLA antenna, a transceiver configured to transmit a transmission signal through the antenna device and receive a reflection signal reflected from an object, and a controller configured to determine an angular power spectrum (APS) for the reflection signal and determine an angle at which the object is located based on the APS.

Abstract: Aspects of the present invention relate to machines, systems, and methods for detecting a morphed image on an ID card associated with a user. The invention may comprise a plurality of security kiosks, a user database, morphed image detection logic, surveillance cameras, a surveillance database, surveillance similarity logic, user identification logic, message logic, and detainment logic. The machines, systems, and methods may assist an operator in controlling access of an individual using an ID bearing a morphed image.

Abstract: Provided is a radar device that may perform an angle estimation of an incoming direction of an incoming wave with high accuracy because of increased angular resolution and has an increased dynamic range. In a transmission antenna Tx, transmission antenna elements Tx1, Tx2, Tx3, and the like of number m of three or more are arranged in a straight line at equal intervals of wavelength ? of a transmission wave. In a reception antenna Rx, reception antenna elements Rx1, Rx2, and the like, are arranged in a straight line at equal intervals. Circuitry generates virtual reception antenna elements Rxa, Rxb, . . . , and Rxq between the respective reception antenna elements by adjusting a phase of a reception signal to control the directivity of a radio wave to perform beam-forming between transmission antenna elements in each pair.

Abstract: An apparatus includes a clock signal input, a sampling circuit, and an estimation circuit. The clock signal input receives N time measurements. A time measurement denotes a respective portion of a given cycle of a clock signal. The sampling circuit is to generate a first sampled window from the clock signal input. The first sampled window includes an accumulation of the N time measurements. The sampling circuit is to generate a second sampled window from the clock signal input including an accumulation of a plurality of products. The estimation circuit is to estimate the frequency or period of the clock signal based upon the first sampled window and the second sampled window.

Abstract: Apparatuses, methods, and systems are disclosed for control information for a digitally controlled surface having reflective elements. One method includes transmitting, from a first network device, a synchronization signal based on a control frame structure to a second network device including a digitally controlled surface having reflective elements. The method includes transmitting control information based on the control frame structure to a controller of the second network device. The control information is transmitted at least partly using a dedicated physical control channel, a sequence, and/or an on-off pattern.

Abstract: A signal sending method, a signal processing method, and a radar apparatus are provided which are, related to sensor technologies. The radar apparatus includes at least three transmit antennas. The signal sending method includes: determining at least two transmit antenna groups of the radar apparatus, wherein each transmit antenna group includes at least one transmit antenna; sending signals by using the at least two transmit antenna groups, wherein the at least two transmit antenna groups send signals in a TDM manner, and a plurality of transmit antennas included in each transmit antenna group including a plurality of transmit antennas in the at least two transmit antenna groups send signals in a CDM manner. Embodiments of this application may be applied to related fields such as autonomous driving, assisted driving, intelligent driving, intelligent connected vehicle, intelligent vehicle, and electric mobile/electric vehicle.

Abstract: The disclosure provides a mounting structure of an object detection device to a vehicle body capable of improving the accuracy of object detection by the object detection device and improving the durability of the object detection device. A mounting structure of a radar device, which is an object detection device for detecting objects, to a vehicle body, includes a cover member attached to the vehicle body side and covering at least a part of the radar device. The cover member is disposed on a first direction side, which is an object detection direction by the radar device when viewed from the radar device. The cover member includes a rib extending from the cover member in a second direction opposite to the first direction. The radar device is fixed to the rib.

Abstract: Embodiments of the present disclosure provide a wireless communication method, a terminal device, and a network device, which can optimize signal tracking and search and reduce signal search delay, thereby improving system performance. The wireless communication method comprises: a terminal device receives first information, the first information being used by the terminal device to search for a signal at a target frequency point, and the first information comprising at least one of the following: ephemeris information associated with the target frequency point, reference information used for adjusting an SMTC window associated with the target frequency point, and cell position or orientation information associated with the target frequency point.

Abstract: Systems and methods are provided for simultaneous beamforming at two close frequency bands. Rotman-lens-based beamforming modules with low size, weight, and power (SWaP) can be used. A stacked array Rotman lens module can use a low cost feeding type of layer-to-layer energy transitions, and the stacked module can be capable of simultaneous beamforming at two close frequency bands.

Abstract: A multi-chip MIMO radar system includes a plurality of transmitters and a plurality of receivers. Each of the pluralities of transmitters and receivers are arranged across a plurality of circuit chips. The multi-chip MIMO radar system includes a central processor configured to receive data from the plurality of circuit chips. The plurality of circuit chips generates sets of selected range, Doppler, and virtual receiver data. The central processor is operable to process the sets of selected range, Doppler, and virtual receiver data to produce selected range detection and angular resolvability of targets.

Abstract: A mechanism is provided to reduce interference between vehicular radar systems through communicating radar parameters and physical orientation between vehicles and then using directional information to form clusters of radars, which will have consistent modulation parameters. Radar modulation parameters, such as starting frequency, center frequency, bandwidth, slope, ramp direction, timing, and the like for frequency-modulated continuous-wave (FMCW) radars, are adjusted to reduce or eliminate inter-cluster direct interference between clusters oriented in different directions. For other types of radars, in some embodiments, other operational parameters can be adjusted. In some embodiments, some modulation parameters also can be adjusted to reduce or eliminate intra-cluster indirect interference.

Abstract: A radar sensor for a motor vehicle, in particular a passenger car, is disclosed. The radar sensor has a control unit, an antenna arrangement, and a reflector device for reflecting transmitted radar signals from the antenna arrangement into a measurement region and radar signals, which are to be received by the antenna arrangement from the measurement region. The reflector device has a parabolic reflector. The control unit is designed to change the measurement region by changing the radiation characteristic and/or the reception characteristic, in particular by beamsteering and/or beamforming, during control of the antenna arrangement such that various reflection regions of the reflector device that correspond to different measuring regions are used.

Abstract: Example radar apparatus and mobile platforms are described. One example radar apparatus includes a housing, an antenna board, and a connector. The antenna board is disposed in the housing. The antenna board has a first board surface and a second board surface that are disposed opposite each other. The first board surface is used to receive and transmit signals. The connector is disposed in the housing, and is configured to connect to another component outside the housing. The connector has an electrical connection structure. The electrical connection structure is electrically connected to the antenna board, and the electrical connection structure is located on a side of the second board surface.

Abstract: Disclosed are aspects of a radar system for a vehicle that includes a radar circuit for generating and processing radar signals, wherein the radar circuit includes a ground plane connector for an electrical connection with an antenna ground plane. The radar system also includes a radar antenna assembly for transmitting radar signals into a traffic space and for receiving radar signals reflected by objects present in the traffic space. The radar system further includes a component of the vehicle. The ground plane connector is electrically connected to the component of the vehicle.

Abstract: A system includes a first substrate layer configured at an initial position. A copper foil is positioned above the first substrate layer. A second substrate layer is configured above the copper foil. The second substrate combined with the copper foil and first substrate layer is configured to be curved/bent into one or more shapes. Antenna elements are composed of the copper foil. A coaxial cable is connected to the copper foil.

Abstract: An antenna system mounted on a vehicle according to the present invention may comprise: a first circuit board configured to be mountable to a metal frame; a second circuit board disposed so as to be spaced apart a predetermined distance from the first circuit board through a metal supporter; and an antenna configured to emit a signal transmitted from a power supply unit, said signal being transmitted through a space between the first circuit board and the second circuit board.

Abstract: Embodiments described herein address these and other issues by providing radio frequency (RF) sensing to determine the status of a driver or other occupant of the vehicle. RF sensing may be provided by existing radios of a vehicle, such a Wi-Fi transceiver, and may therefore provide RF sensing functionality to a vehicle with little added cost. RF sensing can be leveraged to implement safety features such as detecting an unattended child or pet in a vehicle, detecting driver alertness, and the like.

Abstract: An electronic device includes a transmission antenna that transmits a transmission wave, a reception antenna that receives a reflected wave that is the transmission wave having been reflected, and a control unit that detects an object that reflects the transmission wave, based on a transmission signal transmitted as the transmission wave and a reception signal received as the reflected wave. The control unit performs control to detect, as a target, an object having a motion characteristic of a motion of an arm of a person, among objects located around the electronic device.

Abstract: A technique for performing convolution operations is disclosed. The technique includes performing a first convolution operation based on a first convolutional layer input image to generate at least a portion of a first convolutional layer output image; while performing the first convolution operation, performing a second convolution operation based on a second convolutional layer input image to generate at least a portion of a second convolutional layer output image, wherein the second convolutional layer input image is based on the first convolutional layer output image; storing the portion of the first convolutional layer output image in a first memory dedicated to storing image data for convolution operations; and storing the portion of the second convolutional layer output image in a second memory dedicated to storing image data for convolution operations.

Abstract: A wireless multimode system includes: an array of N antenna elements that includes a first portion of M antenna elements and a second portion of L antenna elements; M transmission amplifiers configured to transmit, via the M antenna elements, frames of transmit data, where the frames of transmit data include transmit radar signals and transmit communication signals; M reception amplifiers configured to receive, via the M antenna elements, frames of receive data, where the frames of receive data includes receive communication signals; and L reception amplifiers configured to receive, via the L antenna elements, receive radar signals; and a resource scheduler configured to allocate bandwidth for transmit radar signals and transmit communication signals within the frames of transmit data based on one or more predetermined parameters.

Abstract: A wiring module 20 is included in a power storage module 2 including a plurality of power storage elements 10 each having electrode terminals 11A and 11B and is connected to the power storage elements 10. The wiring module 20 includes a flexible FPC 21A including a first conductive path 23 and a circuit board 30 including a second conductive path that is electrically connected to the first conductive path 23. The FPC 21A includes a main body portion 24 and a circuit connecting portion 27 that extends from the main body portion 24 and is overlaid on the circuit board 30. The first conductive path 23 includes a first land 23A included in the circuit connecting portion 27. The second conductive path includes a second land 32A that is electrically connected to the first land 23A. The connected portion between the first land 23A and the second land 32A is covered by a covering portion 60 constituted by a resin having insulating properties.

Abstract: A generator of a frequency modulated radar signal includes a generator of a periodic signal frequency modulated over a part Tramp of a period T, corresponding to a square signal of which the frequency varies linearly in a first frequency band Bin of central frequency fin; an oscillator generating a sinusoidal signal of frequency fc>fin and included in a second frequency band Bamp>Bin and corresponding to the linear variation of the frequency of the radar signal; and means coupled to an electrical supply input of the oscillator such that they generate a voltage for supplying the oscillator at the frequency of the frequency modulated periodic signal.

Abstract: A radar device is disclosed. The present disclosure in some embodiment provides a radar device configured to detect a target in front by using an antenna configured to transmit and receive a radar signal, including a housing having an upper side formed with an aperture to which a radome is coupled, a radar package disposed inside the housing and comprising the antenna, a signal processor, and a target information calculator, and a circuit board mounted with the radar package and a power block.

Abstract: A system includes a millimeter-wave radar sensor disposed on a circuit board, a plurality of antennas coupled to the millimeter-wave radar sensor and disposed on the circuit board, and a processing circuit coupled to the millimeter-wave radar sensor and disposed on the circuit board. The processing circuit is configured to determine vital signal information based on output from the millimeter-wave radar sensor.

Abstract: Provided are a method and electronic device for inferring an object in an image using a convolutional neural network (CNN) model. The method includes including: identifying a first region of interest in a first frame in the moving image, and a first object in the first region of interest, by providing the first frame to convolution layer groups sequentially connected in the CNN model, identifying a second region of interest in a second frame, the second region of interest corresponding to the first region of interest, and the second frame being after the first frame, providing the second region of interest to the CNN model, and obtaining first output data output from a first convolution layer group from among the convolution layer groups, and determining whether to identify a second object in the second region of interest by using a second convolution layer group, based on the first output data.

Abstract: A radar system is described herein. The radar system includes a printed circuit board (PCB) that includes a metallized top layer and a substrate layer that is adjacent the metallized top layer. The substrate layer includes a substrate integrated waveguide (SIW), and the metallized layer has a slotted taper etched therein. The slotted taper is positioned relative to the SIW such that an electromagnetic signal generated by a monolithic microwave integrated circuit (MMIC) passes from the slotted taper to the SIW without an intervening microstrip line. The radar system further includes a housing that acts both to disperse heat and to suppress undesired electromagnetic radiation.

Abstract: A radome for on-board radar devices 1 is provided with heater wires 3 wired in parallel so as to be separated from each other in a plane direction of an electromagnetic-wave-transmitting base member. A line pitch d of the heater wires 3 arranged in parallel in an electromagnetic-wave transmission region R of the base member is set to 0.2 to 2.5 times a wavelength of electromagnetic waves of the radar of an on-board radar device. A surface occupancy rate of the heater wires 3 arranged in parallel in the electromagnetic-wave transmission region R of the base member is set to be greater than 10% to 35%. The present invention provides a radome for on-board radar devices with which it is possible to obtain an electromagnetic-wave transmission property required of a radome, and to melt snow satisfactorily with a high heater performance.

Abstract: A radar sensor having at least one antenna structure and at least one coupling structure, which is designed to couple substrate waves out of an antenna substrate used as a carrier for the antenna structure and the coupling structure, and to emit them as coupled waves into an emission region. The radar sensor has an absorber which is situated in the emission region in order to absorb the coupled waves.

Abstract: A semiconductor device comprises a substrate having a first surface and a second surface opposite the first surface, at least one connection element arranged on the first surface of the substrate to electrically and mechanically connect the substrate to a printed circuit board, and a radar semiconductor chip arranged on the first surface of the substrate.

Abstract: An electronic device comprises: a transmission antenna configured to transmit transmission waves; a reception antenna configured to receive reflected waves resulting from reflection of the transmission waves; and a controller. The controller is configured to detect an object reflecting the transmission waves, based on a transmission signal transmitted as the transmission waves and a reception signal received as the reflected waves. The controller is configured to make a range of detection of the object by the transmission signal and the reception signal, variable.

Abstract: Examples relate to a method for processing beamformed data of a medium. The beamformed data includes a first set of beamformed data associated with a first spatial region and a second set of beamformed data associated with a second spatial region, and the method includes estimating the clutter caused by the second spatial region at the first set.

Abstract: Systems, circuits, and methods for synchronizing devices in the time-domain are provided. A method, according to one implementation, includes determining a round-trip number based on a width of one cycle of a timestamping clock signal. The round-trip number is equal to a plurality of times that a clock signal is to be transmitted in a loop from a timing-leader component to a timing-follower component and back to the timing-leader component. The method also includes utilizing the timestamping clock signal to detect a cumulative time delay that results when the clock signal is transmitted in the loop a number of times equal to the round-trip number. The cumulative time delay is configured to enable synchronization of the timing-follower component with the timing-leader component.

Abstract: An antenna for improving an influence of surface waves and increasing a beamwidth includes: a substrate, a first metal ground, a second metal ground, an emitting end and a receiving module. The first metal ground and the second metal ground are disposed on a first surface of the substrate. The second metal ground is completely separated from the first metal ground by a first gap. The emitting end is disposed on the first metal ground and includes a transmission line and a plurality of radiating elements. The receiving module is disposed on the second metal ground and includes a first receiving end and a second receiving end. The first receiving end includes a transmission line and a plurality of radiating elements. The second receiving end includes a transmission line and a plurality of radiating elements.

Abstract: Provided is a millimeter-wave radar package module, which relates to antenna packaging. The millimeter wave radar package module includes a package and a plurality of antenna units packaged therein. The package includes a chip, and the chip includes a transmitter and a receiver. The antenna units are respectively connected to an output pin of the receiver and an output pin of the transmitter through a transmission line.

Abstract: A wireless multimode system includes: an array of N antenna elements that includes a first portion of M antenna elements and a second portion of L antenna elements; M transmission amplifiers configured to transmit, via the M antenna elements, frames of transmit data, where the frames of transmit data include transmit radar signals and transmit communication signals; M reception amplifiers configured to receive, via the M antenna elements, frames of receive data, where the frames of receive data includes receive communication signals; and L reception amplifiers configured to receive, via the L antenna elements, receive radar signals; and a resource scheduler configured to allocate bandwidth for transmit radar signals and transmit communication signals within the frames of transmit data based on one or more predetermined parameters.

Abstract: A single-layer Wide Angle Impedance Matching (WAIM) and method for using the same are described. In one embodiment, the antenna comprises: an aperture having a plurality of antenna elements operable to radiating radio-frequency (RF) energy; and a single-layer wide angle impedance matching (WAIM) structure coupled to the aperture to provide impedance matching between the antenna aperture and free space.

Abstract: A vehicular radar sensor includes an emission part for emitting an electromagnetic wave and a reception part for receiving an electromagnetic wave, and a waveguide including a restriction portion, which is open at front and rear surfaces thereof so as to allow an electromagnetic wave to be transmitted therethrough and which is fixed at the open rear surface thereof to the antenna and extends outwards from a front end of the antenna, and a flaring portion, which extends outwards with an increasing cross-sectional area from a front end of the restriction portion.