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Recent Publicity

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http://www.postandcourier.com/business/it-s-on-his-radar-charleston-professor-sees-new-use/article_ea87e2c2-041e-11e7-a259-4f5af69727dd.html



























http://www.charlestonbusinessmag.com/archives/1285

THE CITADEL, THE MILITARY COLLEGE OF SOUTH CAROLINA

171 Moultrie Street, Charleston, SC 29409

Nonlinear Radar for Remotely Finding

and Identifying Handheld Electronics

Anthony F. Martone, Kyle A. Gallagher

U.S. Army Research Laboratory

Adelphi, MD 20783

Ram M. Narayanan

Pennsylvania State University

University Park, PA 16802

Gregory J. Mazzaro

The Citadel, The Military College of South Carolina

Charleston, SC 29409

17-Apr-2017

3

Presentation Overview

• Introduction to Nonlinear Radar

• Concept, Motivations

• Electromagnetic Nonlinearity, Harmonics

• Nonlinear Radar Research

• Harmonic Radar, for Detecting Electronics

• Stepped-Frequency, for Ranging

• Experiments, Results

• Recent Patents

• Future Work

United States

Army Research Laboratory

Synchronous Impulse

Reconstruction Radar

4

Nonlinear Radar Concept

Applications:

Advantages:

• It is easier to separate targets from clutter because most clutter is linear.

Disadvantages:

• Targets require high incident power to drive them into non-linear behavior.

• Received responses are usually very weak compared to the transmitted “probe” signals.

Target presence/location

is indicated by receiving

frequencies that were

not transmitted.

Tx

Rx

• locate personal electronics during emergencies

• detect electronically-triggered devices

electronic

target

5

Sources of Nonlinearity

+

_ +

_

Active elements & components – by design; above system noise floor

Passive elements & components – unintended; below system noise floor

diodes transistors amplifiers mixers

f1

f2

f1 + f2

contacts [1,2]

metal 1

metal 2

oxide

metal

thermal

effects [5] connectors [3]

V R

ferro-electrics [4]

Nearly all electronics are nonlinear, to some degree.

6

Temperature-Dependent

Resistance

Vin R

Iout

voltage applied,

current flows

resistor

heats up

resistance

increases current

decreases

resistor cools

down resistance

decreases

current

increases

input: constant

output: sinusoidal

nonlinear

Vin

time

Iout R

time time

Tx

Rx

7

Nonlinear Radar Research

We view each target as

a collection of RF

nonlinearities.

Ein

Erefl... LNA

BPF

one possible

signal path:

8

Nonlinear Radar Research

Tx

Rx

• Which frequencies and waveforms are best to transmit?

• What is the minimum transmit power required for detection?

• Which is the best antenna design (gain, polarization, etc.) for detection and ranging?

• How should the transmitter be designed to achieve high linearity?

• How should the receiver be designed to achieve high sensitivity?

• How should a signal processor be designed to recognize familiar targets?

This type of

radar research

is in its infancy.

9

Harmonic Radar: Theory

2 3

o u t 1 in 2 in 3 in. . .E a E a E a E

Let the nonlinearity

be approximated by

a power series [6]

Let the input waveform be a sinusoid: in 0 0cosE E t

Then the device response (output) is

2

o u t 1 0 0 2 0 0

3

3 0 0

c o s c o s

c o s ...

E a E t a E t

a E t

o u t 1 0 0

2

2 0 0

3

3 0 0

c o s

2 c o s 2

4 c o s 3 ...

E a E t

a E t

a E t

harmonics

input

output

input = { f }

output = { f, 2f, 3f, 4f, 5f, 6f, … }

10

intermodulation

difference / “beat”

frequencies

harmonics

1

2

9 9 M H z

1 0 1 M H z

f

f

1

2

9 9 M H z

1 0 1 M H z

f

f

input

output

In the frequency domain, nonlinearity

appears as spurious spectral content

(e.g. harmonics, intermodulation).

Intermodulation Radar:

Theory

11

Prior (Published) Work

[8]

[7]

RADAR TAGS for INSECT TRACKING

[9]

• simulations show detection possible > 22 m at 80 GHz

AUTOMOTIVE RADAR for detecting

“VULNERABLE ROAD USERS”

MILITARY RADAR for detecting

MANMADE METALLIC OBJECTS

[10]

NLR for detecting handheld

electronics is novel.

12









• Recent Patents

• Future Work

United States


Synchronous Impulse


13

1-Tone Continuous-Wave

Experiment

step

attenuator

Ptrans

targ

et

antenna

Prec

Tektronix AWG7052

arbitrary waveform generator Amplifier Research

50-W 1-GHz RF amplifier

Rohde & Schwarz FSP

40-GHz spectrum analyzer

Gigahertz Transverse

Electromagnetic cell

We performed our initial nonlinear (harmonic) experiments

wirelessly, at high power, in a controlled environment.

14

GTEM cell, outside, front GTEM cell, outside, back

Gigahertz Transverse


VTx


Experiment

A GTEM cell is essentially

a large, flared waveguide.

[11]

15

target placement GTEM cell, inside

antenna, absorber

VTx

VTx


Experiment

A GTEM cell is essentially

a large, flared waveguide. Gigahertz Transverse


16

Tx band Rx band

~36 dB

gain

~50 dB

gain

The transmitter amplifies each tone

by >3 orders of magnitude to send

2 Watts to the transmit antenna.

The receiver amplifies each

received harmonic received by

~5 orders of magnitude.

Radar Transmitter:

In-House Filter Design

[12]

17


Measurements

We found that many commercially-available RF devices

emit harmonics when illuminated by continuous radar waves.

GTEM cell

18

Nonlinear

Stepped-Frequency Radar

A1

f1

A2

f2

A3

f3

A4

f4

A5

f5

2f0 2f0 + 2Df 2f0 + 4Df 2f0 + 6Df 2f0 + 8Df

amplitude

phase

frequency

…

…

…

…

IFFT

2

cR t

Tra

nsm

itte

d

Rec

eived

P

roce

ssed

After constructing H() of the

environment, an inverse FFT

gives its impulse response.

19

12 ft

quad-ridge

horn antenna

target location

( all targets were place

with antennas oriented

vertically )

Nonlinear Step-Freq Radar:

Experiment

We set up our antenna and targets in a low-metal-content

environment at ARL’s Adelphi Laboratory Center.

20

arbitrary

waveform

generator

20GS/s

oscilloscope

triple-voltage

power

supplies

power

amplifier

Nonlinear Step-Freq Radar:

Experiment

to scope

from power

amplifier

to scope

to/from

antenna directional

coupler

low-noise

amps x3 diplexers

x2

Most of the prototype radar parts

were commercial off-the-shelf

components or standard radio-

frequency laboratory instruments.

Data capture and processing were

performed on a laptop, in Matlab.

[13]

21

Range [ft]

Dopple

r speed [

m/s

]

Nonlinear Moving Target

-10 0 10 20 30 40-1.5

-1

-0.5

0

0.5

1

-40

-35

-30

-25

-20

-15

-10

-5

0

Rec

eiv

ed P

ow

er

(dB

sm,

no

rmal

ized

)

One of the targets was

placed on a moving

platform.

During data capture,

the target moved

towards the radar.

UWB Harmonic Radar:

Moving-Target Results

[14]

22









• Recent Patents

• Future Work

United States


Synchronous Impulse


23

US patent # 9,395,434

“Multitone Harmonic Radar and Method of Use”

24

US patent # 9,435,882

“Method and Apparatus for Cognitive Nonlinear Radar”

25

US patent # 9,476,973

“Combined Radar Assembly with Linear and Nonlinear Radar”

26

Range [ft]

Dopple

r speed [

m/s

]

Nonlinear Moving Target

-10 0 10 20 30 40-1.5

-1

-0.5

0

0.5

1

-40

-35

-30

-25

-20

-15

-10

-5

0

Nonlinear Radar Research:

To-Date & Future

Tx

Rx

We have (a) shown that RF electronics emit harmonics when illuminated by radar waves,

which enables detection of these targets

(b) developed an experimental prototype of a stepped-frequency harmonic radar,

which is able to detect & locate commercially-available RF electronic devices, and

(c) published and patented novel radar hardware designs

to disseminate & protect our research.

We intend to (d) package the radar onto a mobile platform (vehicle), and

(e) develop signal-processing techniques to identify particular targets.

27

References

[1] C. Vicente and H. L. Hartnagel, “Passive-intermodulation analysis between rough rectangular waveguide flanges,” IEEE Transactions on

Microwave Theory and Techniques, Vol. 53, No. 8, Aug. 2005, pp. 2515–2525.

[2] H. Huan and F. Wen-Bin, “On passive intermodulation at microwave frequencies,” in Proceedings of the Asia-Pacific Electromagnetic

Conference, Nov. 2003, pp. 422–425.

[3] J. Henrie, A. Christianson, and W. J. Chappell, “Prediction of passive intermodulation from coaxial connectors in microwave networks,”

IEEE Transactions on Microwave Theory and Techniques, Vol. 56, No. 1, Jan. 2008.

[4] G. C. Bailey and A. C. Ehrlich, “A study of RF nonlinearities in nickel,” Journal of Applied Physics, Vol. 50, No. 1, Jan. 1979, pp. 453-461.

[5] J. R. Wilkerson, K. G. Gard, A. G. Schuchinsky, and M. B. Steer, “Electro-thermal theory of intermodulation distortion in lossy microwave

components,” IEEE Transactions on Microwave Theory and Techniques, Vol. 56, No. 12, Dec. 2008.

[6] J. C. Pedro and N. B. Carvalho, Intermodulation Distortion in Microwave and Wireless Circuits. Boston, MA: Artech House, 2003.

[7] N. Tahir and G. Brooker, “Recent developments and recommendations for improving harmonic radar tracking systems,” in Proceedings of

the 5th European Conference on Antennas and Propagation, Apr. 2011, pp. 1531–1535.

[8] D. Psychoudakis, W. Moulder, C. C. Chen, H. Zhu, and J. L. Volakis, “A portable low-power harmonic radar system and conformal tag for

insect tracking”, IEEE Antennas and Wireless Propagation Letters, Vol. 7, 2008, pp. 444–447.

[9] J. Saebboe, V. Viikari, T. Varpula, and H. Seppa, “Harmonic automotive radar for VRU classification”, in Proceedings of the International

Radar Conference: Surveillance for a Safer World, Oct. 2009, pp. 1–5.

[10] C. L. Opitz, “Radar object detector using non-linearities,” U. S. Patent 4,053,891, Oct. 11, 1977.

[11] G. J. Mazzaro and A. F. Martone, “Harmonic and multitone radar: Theory and experimental apparatus,” U.S. Army Research Laboratory

Technical Report, No. 6235, Oct. 2012.

[12] K. A. Gallagher, G. J. Mazzaro, A. F. Martone, K. D. Sherbondy, and R. M. Narayanan, “Filter selection for a harmonic radar receiver,”

accepted to SPIE Defense, Security, & Sensing 2015, Baltimore, MD, April 2015.

[13] G. J. Mazzaro, K. A. Gallagher, A. R. Owens, K. D. Sherbondy, and R. M. Narayanan, “Ultra-Wideband Harmonic Radar for Locating

Radio-Frequency Electronics,” U.S. Army Research Laboratory Technical Report, No. 7256, Mar. 2015.

[14] K. A. Gallagher, R. M. Narayanan, G. J. Mazzaro, K. I. Ranney, A. F. Martone, and K. D. Sherbondy, “Moving Target Indication with

Non-Linear Radar,” Proceedings of the IEEE Radar Conference, pp. 1428-1433, May 2015.

Recent Publicity - Citadelece.citadel.edu/mazzaro/seminars/IEEE_Citadel_Apr17_NLR.pdfRecent Publicity ... THE CITADEL, THE MILITARY COLLEGE ... “A study of RF nonlinearities in nickel,”

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