HARMONIC RADAR DETECTING AND RANGING SYSTEM FOR AUTOMOTIVE VEHICLES
First Claim
1. A detecting and ranging system for use with an automotive vehicle, comprising a transmitter, a receiver, an output means and a directional antenna network coupled to said transmitter and said receiver;
- said transmitter comprising means for generating electromagnetic energy signals of a predetermined frequency;
said receiver comprising means adapted to detect electromagnetic energy signals which are derived from and harmonically related to said signals of said predetermined frequency;
said output means being coupled to said receiver and cooperating with said receiver for producing an output signal in response to said detected signals; and
said antenna network including means for selectively transmitting said signals of said predetermined frequency into a given transmission direction while polarizing said transmitted signals into a given polarization direction, said antenna network further including means selectively responsive only to electromagnetic signals originating from said given transmission direction, which signals have been derived from and are harmonically related to said transmitted signals and which have a polarization direction substantially orthogonal to said given polarization direction, for applying said selectively derived signals to said receiver.
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Abstract
In a vehicular harmonic radar detecting and ranging system, a transmitter transmits a highly directional and polarized beam of electromagnetic energy, preferably in the microwave spectrum, toward a passive target. The passive target reradiates a beam of energy, which is harmonically related to and polarized orthogonal to the transmitted beam, directionally back toward the transmitter. A receiver by being selectively responsive the the harmonically related and orthogonally polarized reradiated beam, is immune to blinding which would otherwise be caused by the transmitted signals of other radar equipped vehicles and to the clutter caused by extraneous targets.
71 Citations
11 Claims
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1. A detecting and ranging system for use with an automotive vehicle, comprising a transmitter, a receiver, an output means and a directional antenna network coupled to said transmitter and said receiver;
- said transmitter comprising means for generating electromagnetic energy signals of a predetermined frequency;
said receiver comprising means adapted to detect electromagnetic energy signals which are derived from and harmonically related to said signals of said predetermined frequency;
said output means being coupled to said receiver and cooperating with said receiver for producing an output signal in response to said detected signals; and
said antenna network including means for selectively transmitting said signals of said predetermined frequency into a given transmission direction while polarizing said transmitted signals into a given polarization direction, said antenna network further including means selectively responsive only to electromagnetic signals originating from said given transmission direction, which signals have been derived from and are harmonically related to said transmitted signals and which have a polarization direction substantially orthogonal to said given polarization direction, for applying said selectively derived signals to said receiver.
- said transmitter comprising means for generating electromagnetic energy signals of a predetermined frequency;
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2. The system according to claim 1 wherein said receiver includes means coupled to said transmitter wherein said output signal is proportional to the difference in frequency between a preselected harmonic of said predetermined frequency and said selectively derived signals.
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3. The system according to claim 1, wherein said output means includes means coupled to said transmitter wherein said output signal is derived by comparing said predetermined frequency signal and said selectively derived signals.
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4. The system according to claim 2, including frequency modulation means coupled to said transmitter to vary the frequency of the signals generated by said transmitter about said predetermined frequency.
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5. The system according to claim 1, wherein the frequency of said selectively derived signals is the second harmonic of said predetermined frequency
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6. The system according to claim 5, wherein said antenna network comprises a unitary antenna structure and wherein said means for selectively transmitting said signals of said predetermined frequency includes a first array of dipole elements having a resonant frequency substantially equal to said predetermined frequency and a polarization direction determinative of said given polarization direction, and wherein the selectively responsive means includes a second array of dipole elements having a resonant frequency substantially equal to the second harmonic of said predetermined frequency and a polarization direction orthogonal to said given polarization direction.
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7. A detecting and ranging system for use with an automotive vehicle, comprising a transmitter, a receiver, an output means and a directional antenna network coupled to said transmitter and said receiver;
- said transmitter comprising means for generating electromagnetic energy signals of a predetermined frequency;
said receiver comprising means adapted to detect electromagnetic energy signals which are derived from and harmonically related to said signals of said predetermined frequency;
said output means being coupled to said receiver and cooperating with said receiver for producing an output signal in response to said detected signals; and
said antenna network including means for selectively transmitting said signals of said predetermined frequency in the direction of forward movement of the vehicle and onto a target comprised of a retrodirective harmonic reflector mounted on the rearward portion of a preceding vehicle, while polarizing said transmitted signals into a given polarization direction, said antenna network further including means selectively responsive only to the reflected electromagnetic energy signals which are harmonically related to said transmitted signals and have a polarization direction substantially orthogonal to said given polarization direction for applying said harmonically related and orthogonal signals to said receiver.
- said transmitter comprising means for generating electromagnetic energy signals of a predetermined frequency;
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8. The system according to claim 7, wherein said retrodirective harmonic reflector includes a harmonic generating means coupled between a first and second directive antenna, said first antenna having a polarization direction corresponding to said given direction and a resonant frequency substantially equal to said predetermined frequency, said second antenna having a polarization direction which is substantially orthogonal to the polarization direction of said first antenna and a resonant frequency substantially equal to a preselected harmonic frequency of said predetermined frequency.
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9. The system according to claim 8, wherein said preselected harmonic frequency is the second harmonic of said predetermined frequency.
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10. The system according to claim 8 wherein said harmonic generating means comprises a diode.
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11. The system according to claim 7, including frequency modulation means coupled to said transmitter to vary the frequency of the signals generated by said transmitter about said predetermined frequency;
- and wherein said receiver includes means coupled to said transmitter to provide an output signAl which is proportional to the difference in frequency between a preselected harmonic frequency of said predetermined frequency and said selectively derived signals.
Specification