A Non-Linear Junction Detector (NLJD) is well-known method of detecting hidden transmitters and/or other electronics (even when powered off) by transmitting a clean, low-power 900 MHz signal and displaying the received signal strengths of the returned second (1800 MHz) and third (2700 MHz) harmonics.  By comparing the received harmonic's signal strengths, an operator can distinguish between a dissimilar metal non-linear junction, such as some rusty nails, or an actual PN junction, such as a diode or transistor.  That's the idea at least.

In theory, one could covertly scan a person from a distance to observe them for any signs of dissimilar metal non-linear junctions.  This could be an indication the person is carrying nails, ball bearings, etc. which have been used in making bombs.  Or maybe, it's just two touching paper clips...

Block Diagrams

        

    Which road would you position a bomb detector on?

Frequency Layout

    Transmitter - Fundamental : 908.8 MHz
   Transmitter - 2nd Harmonic : 1817.6 MHz
   Transmitter - 3rd Harmonic : 2726.4 MHz

1st LO - 2nd Harmonic Receive : 2246.4 MHz
1st LO - 3rd Harmonic Receive : 2297.6 MHz
                       1st IF : 428.8 MHz

                       2nd LO : 439.5 MHz 
                       2nd IF : 10.7 MHz

Schematics

Under Construction

• GBPPR Non-Linear Junction Detector - Transmitter  (307k PNG)
• GBPPR Non-Linear Junction Detector - Transmitter  (55k PostScript)
• GBPPR Non-Linear Junction Detector - 1st IF  (327k PNG)
• GBPPR Non-Linear Junction Detector - 1st IF  (54k PostScript)
• GBPPR Non-Linear Junction Detector - 2nd IF  (275k PNG)
• GBPPR Non-Linear Junction Detector - 2nd IF  (47k PostScript)
• GBPPR Non-Linear Junction Detector - Resolution / Log Detector  (136k PNG)
• GBPPR Non-Linear Junction Detector - Resolution / Log Detector  (25k PostScript)

Datasheets

• M/A-Com AT-108 Voltage Variable Absorptive Attenuator  (47k PDF)
• Crystek CVCO55CT-0902-0928 902-928 MHz VCO  (181k PDF)
• Z-Comm V800ME05 2270-2360 MHz VCO  (96k PDF)
• Z-Comm V440MC02 370-460 MHz VCO  (47k PDF)
• Texas Instruments OP27 Op-Amp  (313k PDF)
• Pacific Monolithics PM2111 RF Power Amplifier  (947k PDF)
• Fujitsu MB506 UHF Prescaler  (65k PDF)
• Fujitsu MB501 UHF Dual-Modulus Prescaler  (115k PDF)
• M/A-Com 1700 MHz High Pass Filter  (53k PDF)
• Mini-Circuits VNA25 MMIC Amplifier  (55k PDF)
• Pacific Monolithics PM2202 Low Noise Amplifier  (648k PDF)
• WJ Communications AH31 High Dynamic Range IF Amplifier  (267k PDF)
• M/A-Com Dual Band Diplexer  (146k PDF)
• Toko 492S-1053A Filter  (53k PDF)
• Toko 4DFA Series Filter  (150k PDF)
• ECS-10.7-15A Monolithic Crystal Filter  (244k PDF)
• Analog Devices AD603 IF Amplifier  (241k PDF)
• Analog Devices AD8307 Logarithmic Amplifier/Detector  (403k PDF)
• LM3914 LED Display Driver  (375k PDF)
• MC145151 / MC145152 PLL Frequency Synthesizer  (444k PDF)
• 74HC4049 Hex Inverter  (40k PDF)
• Ramsey Electronics LPY2 900 - 2700 MHz Yagi Antenna

Notes

• Non Linear Junction Detector Review and Tutorial
• Understanding Non-Linear Junction Detecting
• REI NJE-4000 "ORION" NLJD
• Overview of the REI NJE-4000 "ORION" NLJD
• Review of the REI NJE-4000 "ORION" NLJD  by Fuller Group Security
• 4059C Diviner NLJD
• Winkelmann HAWK 450 XD NLJD  (250k PDF)
• Xtek Locator Pro+ NLJD
• Bahia 21 RFD 23 NLJD
• Audiotel SuperBroom NLJD
• ISA Boomerang NLJD
• Security Research Broom NLJD  (176k PNG)
• Microlab/FXR SuperScout NLJD - Page 1
• Microlab/FXR SuperScout NLJD - Page 2
• NLJD in Action!
• Screen Capture of Gene Hackman Using a NLJD in The Conversation
• Slot Spiral Antenna with Integrated Balun and Feed  U.S. Patent 5,815,122  (543k PDF)
• Non-Linear Junction Detector  U.S. Patent 6,057,765 (REI)  (1.3M PDF)
• Pulse Transmitting Non-Linear Junction Detector  U.S. Patent 6,163,259 (REI)  (1.6M PDF)
• Radar Object Detector Using Non-Linearities  U.S. Patent 4,053,891  (240k PDF)
• Transponder for use in Locating Avalanche Victims  U.S. Patent 4,331,957  (442k PDF)
• Non-Linear Junction Detector  U.S. Patent 6,897,777 (Audiotel)  (659k PDF)
• System and Method of Radar Detection of Non-Linear Junctions  U.S. Patent 6,765,527  (908k PDF)
• Non-Linear Junction Detector Note #1
• Non-Linear Junction Detector Note #2