# US 2009/0262011 A1 · Instantaneous Radar Polarimetry

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- Number: US 2009/0262011 A1
- Document ID: US20090262011A1
- Status: Published application
- Kind: A1
- Application number: 12/084,452
- Filed: 2005-12-06
- Published: 2009-10-22
- Earliest claimed: 2005-12-06
- Inventors: Arthur Robert Calderbank; Stephen David Howard; William Moran
- Web page: https://patentgrep.com/patent/US20090262011A1

## CPC

- G01S 7/024: {using polarisation effects (in waveguides H01P1/165; for aerials H01Q, e.g. H01Q15/22, H01Q15/24, H01Q19/195)}
- G01S 13/284: {using coded pulses}
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES

## Abstract

A radar system and method that employs polarization-time diversity in transmitting signals and concurrently processing received reflections from both polarization modes provides information about the scattering matrix of a target without loss of information. Illustratively, the transmitted signals from Golay pairs, and the processing method employs a complex-conjugate time reversal operand. The received reflected signals are processed for a particular distance in mind to develop a scattering matrix of the medium at that distance. By comparing the scattering matrix to known scattering matrices an identification of the target from where the transmitted signals were reflected is obtained.

## Claims

### Claim 1

A method for developing information about objects that reflect electromagnetic signals that reach the objects, comprising the steps of:
transmitting a first signal in a first polarization mode and a second signal in a second polarization mode, where the first polarization mode is orthogonal to the second polarization mode;
transmitting a third signal in the first polarization mode and a second signal in the said second polarization mode;
receiving a fifth signal having said first polarization mode that results from said first signal and from said second signal, a sixth signal having said second polarization mode that results from said first signal and from said second signal;
receiving a seventh signal having said first polarization mode that results from said third signal and from said fourth signal, an eighth signal having said second polarization mode that results from said third signal and from said fourth signal;
processing said fifth signal, said sixth signal, said seventh signal and said eighth signal together to create said information about objects; and
employing the created information to characterize object that produced said fifth, sixth, seventh and eighth signals.

### Claim 2 (depends on 1)

The method of claim 1 where said first signal and said second signal are transmitted concurrently and where said third signal and said fourth signal are transmitted concurrently.

### Claim 3 (depends on 1)

The method of claim 1 where said first signal is a first digital sequence of bits having a selected chip rate, and the second signal is a second digital sequence of bits having a selected chip rate.

### Claim 4 (depends on 3)

The method of claim 3 where the third digital sequence is the negative complex-conjugate time reversed replica of the second digital sequence and the fourth signal is a complex conjugate time reversed replica of the first signal.

### Claim 5 (depends on 4)

The method of claim 4 where the first digital sequence and the second digital sequence form a Golay pair.

### Claim 6 (depends on 4)

The method of claim 4 where the first and second signals are transmitted concurrently and the third and fourth signals are transmitted concurrently, while the first and second signals pair and third and fourth signals pair transmitted alternately.

### Claim 7 (depends on 3)

The method of claim 3 where the first signal and the second signal are transmitted alternately at a data rate that is higher than the chip rate.

### Claim 8 (depends on 1)

The method of claim 1 where the processing develops a scattering matrix
H
=
(
h
VV
h
VH
h
HV
h
HH
)
where hVV is represents a signal having the first polarization received in response to a transmitted impulse having the first polarization, hVV is represents a signal having the first polarization received in response to a transmitted impulse having the first polarization, hVH is represents a signal having the first polarization received in response to a transmitted impulse having the second polarization, and hHV is represents a signal having the second polarization received in response to a transmitted impulse having the first polarization, and hHH is represents a signal having the second polarization received in response to a transmitted impulse having the second polarization.

### Claim 9 (depends on 8)

The method of claim 8 the step of employing forms a decision based on magnitude of coefficients of said hVV, hVV, hVH, hHV, and hHH signals.

### Claim 10 (depends on 8)

The method of claim 8 where the step of employing forms a decision based on comparison of said matrix H to a benchmark matrix.