Abstract: An automotive radar test system includes circuitry for multiple down and up conversions of a signal from the automotive radar. Conditioning circuitry delays an intermediate frequency signal (IF2) obtained after a second down conversion to simulate the delay of a return signal from an object located a particular distance from the automotive radar, and to attenuate the IF2 signal to simulate variable target sizes, and to generate a Doppler shift in the IF2 signal to simulate target speed. The conditioned signal is up-converted and transmitted back to the automotive radar system to determine if the automotive radar provides accurate readings for distance, size and speed. The radar test system further couples the second IF signal to a spectrum analyzer to determine if the automotive radar is operating in the desired bandwidth and to a power meter to determine if the automotive radar is transmitting at a desired power level.

Abstract: A radar test system for testing the performance of an automotive radar system includes circuitry for multiple down and up conversions of a signal from the automotive radar. Conditioning circuitry is further included to delay an intermediate frequency signal (IF2) obtained after the second down conversion to simulate the delay of a return signal from an object located a particular distance from the automotive radar system, and to attenuate the IF2 signal to simulate variable target sizes, and to generate a Doppler shift in the IF2 signal to simulate target speed. The conditioned signal is up-converted and transmitted back to the automotive radar system to determine if the automotive radar provides accurate readings for distance, size and speed.

Abstract: A test system is provided operating in the 76-77 GHz range for testing components of a collision avoidance radar system. The system uses a Scorpion vector network analyzer (VNA) having an internal stimulus source synthesizer operating over a narrow 3-6 GHz range. The source signal from the Scorpion VNA is up-converted in a test module to a 75-78 GHz signal, without using a non-linear multiplier between the Scorpion VNA source and a device under test (DUT). A 72 GHz. local oscillator (LO) signal is provided for up-conversion as well as down-conversion using a dielectric resonator oscillator (DRO) phase-locked to a crystal oscillator of the Scorpion VNA. The DRO is included internal,to the test module. Fundamental up-conversion and down-conversion is provided in the test system so that significant conversion losses do not occur, as when higher order harmonics are used.

Abstract: Two receive antennas integrated with power detectors are used to align the thrust vector of a vehicle to the boresite of an automotive radar antenna mounted upon the vehicle. In the system, a signal is transmitted from the radar antenna to the Radar Test System (RTS) positioned as an amplitude only interferometer for testing the radar. Signals received by the RTS antennas are provided to amplitude detectors for generation of amplitude plots of a difference signal, or alternative signal, for display. The boresite angle of the radar antenna is then adjusted until the amplitude of the difference signal, or alternative signal, reaches a minimum to align the radar antenna boresite with the vehicle thrust vector. Additional pairs of receive antennas and detectors may be used to provide boresite alignment both in azimuth and elevation.

Abstract: A transponder (200) is attached to a laser alignment fixture (210) and used to align an automobile collision avoidance radar antenna boresite with the thrust vector of the vehicle. The alignment fixture (210) has attached reflectors for alignment with two laser beams. To align the collision avoidance radar, the transponder (200) is positioned along the thrust vector of the automobile using a first laser beam (203) aligned perpendicular to a wheel axle. The first laser beam (203) is aligned when transmitted from the wheel axle onto a first piece of reflective material attached to the alignment fixture (210). A second laser (216) is provided parallel to the centerline of the collision avoidance radar antenna to remove azimuth and elevation translation errors between the transponder antenna centerline and the collision avoidance radar antenna centerline. The second laser beam (216) is aligned when transmitted from the automobile onto a second piece of reflective material attached to the alignment fixture (210).

Abstract: A wafer probe with built in components to perform frequency multiplication, upconversion, downconversion, and mixing typically performed by an RF module of a vector network analyzer (VNA). The wafer probe is designed for testing integrated circuits used in collision avoidance radar systems and operates over the 76-77 GHz frequency range allocated by the Federal Communications Commission (FCC) for collision avoidance radars. To minimize costs, the wafer probe preferably utilizes integrated circuits for frequency multiplication, upconversion, downconversion, and mixing manufactured for collision avoidance radar systems.

Abstract: An automobile collision avoidance radar antenna alignment system includes a first interferometer (506) with antennas (501) and (503) for alignment along an azimuth (x) axis of the collision avoidance radar antenna, and a second interferometer (508) with antennas (502) and (504) for alignment along an elevation (y) axis of the collision avoidance radar. Difference azimuth (.DELTA..sub.AZ) and difference elevation (.DELTA..sub.EL) outputs of the interferometers (506) and (508) are added (.DELTA..sub.T =.DELTA..sub.AZ +.DELTA..sub.EL) with the amplitude of (.DELTA..sub.T) provided at a power detector (526). Sum azimuth (.SIGMA..sub.AZ) and sum elevation (.SIGMA..sub.AZ) are added (.SIGMA..sub.T =.SIGMA..sub.AZ +.SIGMA..sub.EL) with the amplitude of (.SIGMA..sub.T) provided to a power detector (547). To align a collision avoidance radar antenna, the antennas of the antenna alignment system are positioned with a centerline parallel to the thrust vector of the automobile using a laser beam fixture 204.

Abstract: A radar test system for testing a collision avoidance radar system. The radar test system includes circuitry to downconvert a signal from the collision avoidance radar to an intermediate frequency signal, to delay the intermediate frequency signal to simulate the delay of a return signal from an object located a particular distance from the collision avoidance radar system, and to upconvert and transmit the intermediate frequency signal back to the collision avoidance radar system to determine if the collision avoidance radar system provides accurate distance readings. The radar test system further couples the intermediate frequency signal to a spectrum analyzer. The spectrum analyzer can be used to determine if the collision avoidance radar system is operating within the 76-77 GHz frequency band allocated by the Federal Communications Commission (FCC). The radar test system further couples the intermediate frequency signal to a power meter.

Abstract: A calibration technique for a vector network analyzer (VNA) enabling calibration standards to be included internal to the VNA. To calibrate the VNA utilizing the internal calibration standards, error terms a, b and c of two two-port error boxes E are defined between the measurement ports and the reflectometer of the VNA wherein a=-det(E), b=e00 and c=e10. Error terms a, b and c are determined by measuring external calibration standards with known reflection coefficients connected directly to the measurement ports. Reflection coefficients for internal calibration standards are then determined using the error terms a, b and c to enable future automatic calibrations. To measure S-parameters of an arbitrary device under test (DUT), one embodiment of the present invention uses the Ferrero technique to measure a reciprocal thru with estimated S.sub.21 characteristics connected between ports A and B to determine an additional error term .alpha. for the error boxes E, where .alpha.=e01.sub.A /e.sub.01B.

Abstract: A calibration technique for a vector network analyzer (VNA) enabling calibration standards to be included internal to the VNA. To calibrate the VNA utilizing the internal calibration standards, error terms a, b and c of two two-port error boxes E are defined between the measurement ports and the reflectometer of the VNA wherein a=-det(E), b=e00 and c=e10. Error terms a, b and c are determined by measuring external calibration standards with known reflection coefficients connected directly to the measurement ports. Reflection coefficients for internal calibration standards are then determined using the error terms a, b and c to enable future automatic calibrations. To measure S-parameters of an arbitrary device under test (DUT), one embodiment of the present invention uses the Ferrero technique to measure a reciprocal thru with estimated S.sub.21 characteristics connected between ports A and B to determine an additional error term .alpha. for the error boxes E, where .alpha.=e01.sub.A /e.sub.01B.

Abstract: A measurement system is provided which comprises: source circuit for receiving feedback signals and for providing respective signals at respective discrete frequencies in a prescribed microwave frequency range, wherein the respective provided signals at respective discrete frequencies are substantially phase locked to at least one downconverted signal in response to the feedback signals; downconverting circuit for linearly downconverting the respective provided signals and for providing the at least one respective downconverted signal; and phase detector circuit for receiving the at least one respective downconverted signal and for providing the feedback signals.

Abstract: YIG oscillator apparatus comprises both an FET-based YIG oscillator circuit and a bipolar transistor-based YIG oscillator circuit inside a single magnetic structure. Both YIG spheres are disposed in the single air gap of the magnetic structure, which is defined by a pole piece which is tapered to an elongated pole surface which is only slightly larger than necessary to cover both YIG spheres. A band reject filter is included inside the housing for rejecting second harmonics of desired oscillation frequencies only.

Abstract: Apparatus for measuring the noise parameters of a device under test (DUT), with full compensation for impedance mismatches between the DUT and the test apparatus. The apparatus includes an S-parameter measuring device, such as vector network analyzer (VNA), combined with a noise module. The noise module includes, among other things, a pair of test ports for the DUT, a noise source which can be turned on or off by an external controller, a receiver, and a switch for coupling the output of the DUT to selectably either the receiver or port 2 of the VNA.

Abstract: YIG oscillator apparatus comprises both an FET-based YIG oscillator circuit and a bipolar transistor-based YIG oscillator circuit inside a single magnetic structure. Both YIG spheres are disposed in the single air gap of the magnetic structure, which is defined by a pole piece which is tapered to an elongated pole surface which is only slightly larger than necessary to cover both YIG spheres.

Abstract: A method and apparatus comprising a sampler frequency converter having a first and a second diode. A local oscillator having a frequency F.sub.LO, a step recovery diode and a balun transformer are used for providing positive and negative sampling pulses to the diodes for sampling an input signal applied to the diodes having a frequency F.sub.IN. An output signal is provided by the diodes having a frequency F.sub.OUT which is defined by the relationship F.sub.OUT .vertline.F.sub.IN .+-.N.times.F.sub.LO .vertline. where N is an integer harmonic number 1, 2, 3 . . . and the output signal has an amplitude which varies as a function of (sin x)/x where x=F.sub.IN. A bandpass filter is provided which is responsive to the output signal for filtering a predetermined band of frequencies therefrom and a bias circuit is provided for forward biasing the diodes so that the frequency F.sub.

Abstract: A vector network analyzer comprising a circuit for measuring the real and imaginary components of the central spectral line in an RF pulse from a device-under-test is provided. The circuit comprises a modulator in response to a profiling pulse for modulating the amplitude of the RF pulse, mixers for down-converting the frequency of the amplitude modulated RF pulse, a narrow band filter for filtering the RF pulse having a bandwidth of 500 Hz and a synchronous detector responsive to the output of the crystal filter for providing a pair of dc outputs, which correspond to the real and imaginary components of the output of the device under test as the profiling pulse is shifted in time relative to the RF pulse.

Abstract: An asymmetrical coupling circuit for use in a network analyzer is provided with a pair of couplers coupled to the input and output ports of a device under test (DUT) for improving the dynamic range of forward and reverse transmission measurements. The through-arms of the couplers are used to connect the input and output ports of the DUT to the reference signal source and measuring circuit to thereby eliminate the attenuation caused by feeding a signal through the coupling arm of the coupler as occurs in symmetrical coupler arrangements.