摘要:
An onboard directional plane antenna comprises at least one array of radiating-slot waveguides comprising an alternating succession of three superposed metallic plates and of two dielectric substrates. The two substrates each comprise at least four adjacent waveguides, corresponding and communicating with one another pairwise by way of coupling slots. Each waveguide of the upper substrate furthermore comprises a plurality of radiating slots passing through the upper metallic plate, all the radiating slots of one and the same waveguide being parallel to one another and oriented in one and the same direction, the radiating slots of two adjacent waveguides being disposed in chevrons. Each waveguide of the lower substrate comprises an internal individual feed circuit comprising an individual electronic circuit for phase shifting and amplification.
摘要:
A short range millimeter wave surface imaging radar system. The system includes electronics adapted to produce millimeter wave radiation scanned over a frequency range of a few gigahertz. The scanned millimeter wave radiation is broadcast through a frequency scanned transmit antenna to produce a narrow transmit beam in a first scanned direction (such as the vertical direction) corresponding to the scanned millimeter wave frequencies. The transmit antenna is scanned to transmit beam in a second direction perpendicular to the first scanned direction (such as the horizontal or the azimuthal direction) so as to define a two-dimensional field of view. Reflected millimeter wave radiation is collected in a receive frequency scanned antenna co-located (or approximately co-located) with the transmit antenna and adapted to produce a narrow receive beam approximately co-directed in the same directions as the transmitted beam in approximately the same field of view. Computer processor equipment compares the intensity of the receive millimeter radar signals for a pre-determined set of ranges and known directions of the transmit and receive beams as a function of time to produce a radar image of at least a desired portion of the field of view. In preferred embodiment the invention is mounted on a truck and adapted as a FOD finder system to detect and locate FOD on airport surfaces.
摘要:
A collision avoidance system for use with an unmanned vehicle, the system includes a plurality of radar elements arranged parallel to the longitudinal axis of the unmanned vehicle, wherein the radar elements transmit a plurality of pulses about the vehicle and receive a plurality of return signals from one or more objects within the range of the vehicle. Upon detecting the one or more objects within range of the vehicle, the system determines if an object is on a course which requires evasive action and suitably alters the vehicle's course in order to avoid collision.
摘要:
A transformer between waveguide and transmission-line includes a high-frequency circuit module, transmission-lines, a waveguide, and feed pins. The high-frequency circuit module has differential-pair terminals to input and output a differential signal. The transmission-lines are connected to the differential-pair terminals. The waveguide includes a first to third metal walls. The feed pins are connected to the transmission-lines inside of the waveguide. The feed pins have a first distance of approximately (λg/2) from each other. One of the feed pins has a second distance of approximately (λg*(1+2 α)/4) from the third metal plane. “λg” is a wavelength in the waveguide and “α” is an integer which is equal or larger than “0”. Each of the feed pins has a third distance of approximately (a/2) from the first or second wall. “a” is length of the waveguide along the third metal wall.
摘要:
An antenna array is provided having a waveguide cavity. The waveguide cavity has a plurality of holes formed on the top surface thereof. Radiating elements are provided on the top surface, each about one of the holes. A radiation source coupled planar wave radiation through an opening in one of the sides of the waveguide cavity.
摘要:
A radar detection process includes computing a derivative of an FFT output signal to detect an object within a specified detection zone. In one embodiment, a zero crossing in the second derivative of the FFT output signal indicates the presence of an object. The range of the object is determined as a function of the frequency at which the zero crossing occurs. Also described is a detection table containing indicators of the presence or absence of an object within a respective radar beam and processing cycle. At least two such indicators are combined in order to detect the presence of an object within the detection zone and with changing range gates in each of the antenna beams the coverage of the detection zone can be varied.
摘要:
A short ridge waveguide load is described which absorbs and cancels non-radiated electromagnetic energy in continuous slot or discrete slotted antennas. The load achieves a small physical size by using a resonant structure which includes an absorbing ferrite front section positioned within the interior of the waveguide antenna below the slot and a back section of ferrite material also positioned in the interior of the waveguide antenna. This allows for energy to be radiated from the slot while absorbing and canceling the non-radiated energy using a relatively small size load. In a rectangular ridge waveguide configuration, the front section consists of a pair of posts having a trapezoidal, rectangular or triangular shape.
摘要:
A slot antenna element is provided in the form of a rectangular waveguide including at least one slot situated in the center of one broad side, a rectangular ridge arranged in the center of the interior surface of the other broad side, wherein the slot and the ridge each extend along the longitudinal direction of the waveguide, coupling devices, particularly a pin, arranged in the area of the slot, which excite the slot to emit electromagnetic energy, and compensation devices constructed on the surface of the ridge facing the slot, which compensation devices compensate the mismatch of the waveguide caused by the coupling devices with respect to the generator feeding the waveguide with electromagnetic energy. The compensation devices are constructed such that the ridge has a step-shaped indentation in the area of the slot.
摘要:
A waveguide portion has a waveguide with a rectangular section surrounded by a pair of narrow side plates opposed to each other, a pair of broad side plates extending along lengthwise directions of the pair of narrow side plates. A radiation portion is provided on one broad side plate of the pair of broad side plates of the waveguide portion, and has a plurality of slots for radiating an electromagnetic wave input into the waveguide portion externally from the one broad side plate. The waveguide portion includes a first waveguide member and a second waveguide member, and is constituted by joining the first waveguide member and the second waveguide member at edge portions extending in longitudinal directions thereof matching with central lines of the pair of broad side plates. The plurality of slots of the radiation portion has a first group of slots and a second group of slots defined respectively in the first waveguide portion and the second waveguide portion at predetermined intervals in a staggered manner. The first group of slots and the second group of slots are provided such that one set of sides of the respective slots are coincident with the central lines of the pair of broad side plates.
摘要:
A radar transmitter includes a digital ramp generator circuit for generating a VCO control signal. The ramp generator includes a digital signal processor and a digital-to-analog converter. In one embodiment, the VCO output signal is up-converted to provide the transmit signal and in another embodiment, the VCO operates over the transmit frequency. Also described is a VCO comprising a DR and a phase shifter. A temperature compensation feature includes detecting the transmit frequency and comparing the DSP output generating the detected frequency to a DSP output stored in association with the detected frequency. Also described is a technique for compensating for non-linear VCO operation in which the DSP output words are adjusted to provide a waveform complementary in shape to the non-linear VCO characteristic. Susceptibility of the radar to interference is reduced by randomly varying at least one parameter of the ramp signal, such as offset interval or voltage range, in at least one ramp signal cycle.