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Non Linear Junction Detectors

Non-linear junction detectors (NLJD) are devices designed for search and detection of different types of covert listening devices, various electronic appliances and transmitters comprising of semiconductors. The principle of NLJD equipment operation is based on emission of high radio frequency energy in an area. Detectors have a sensitive receiver designated for reception of objects’ echo signals which, for operator’s convenience, are marked down with sound or displayed on graphical user’s interface.

Depending on the model, non-linear junction detectors are capable of detecting almost any electronic appliance in any operational mode: active, stand-by, switch-off. The designation of such devices consists in detection of radio microphones, microphone amplifiers, dictophones in premises (walls, floors, ceilings, furniture, etc.). Non-linear junction detectors acquired a reputation as perfect means of counter-espionage, as embassies and other diplomatic posts are known to be most popular targets for eavesdropping equipment. Specific models of NLJD are used by the police in search for weapons during events involving great masses of people. Detectors are used for providing location secure from covert listening devices in different organizations. Non-linear junction detectors can serve multiple purposes and have a wide range of implementation, starting from ground detectors up to equipment used for detection of mobile phones. Wide range of NLJD is presupposed by the type of material or surface for search operations – ground detectors are preferable for object detection in soil, portable detectors tuned to appropriate frequency are better in search within wooden furniture.

One shouldn’t neglect the importance of correct frequency tuning of NLJD equipment for different types of search environment (for instance, concrete walls). Bugs or wires (as covert listening devices are commonly called) can be set up deep in concrete columns and they still will be transmitting signals. As an interesting fact, in 1970s Americans detected wires in the concrete columns of the American Embassy in Moscow. The bugs were installed during the construction of the building, and there was no other way to extract them except for complete destruction of the building.

Non-linear junction detectors have a very peculiar designation, therefore their usage is conditioned by goals set by customers. Taking into account great variety of NLJD equipment there is a specific model for any purpose you may require.


The Company’s priority is a development of Non-Linear Junction Detector (NLJD)  technology. Current NLJD products line include models for various applications.

Why Non Linear Junction Detectors?

NLJD technology has proven to be most effective in detection of semiconductors containing multiple layers of silicon, a P-Type and an N-Type. The point where they meet is called a Non Linear Junction. 

Non Linear Junction also appears in nature:

• dissimilar metals in contact with one another;

• the rust on metals resulting from corrosion.






Multipurpose non-linear junction detector
Has been tested in Croatian Mine Action Centre – Centre for Testing, Development and Training (HCR-CTRO)


searching for various electronic devices that contains semi-conductor components




Professional non-linear junction detector

eavesdropping device and similar electronic appliances detection in premises (radio microphones, microphone amplifiers, dictaphones, etc.)    

electronic units detection in any operational mode: active, stand-by or switched off 




Selective pulse metal detector

search for metallic items their shape and dimensions evaluation against homogeneous background with possible metallic insertions 

searching for thin-wall metallic housings of electronic units concealed in building structures with regular reinforcement (floors, ceilings, walls)




Non-linear detector


√ Detection of mobile phones

√ Searching of Improvised Explosive Devices (electronic control systems of IEDs) at background of complex man-made interference from urban constructions

√ Detection of concealed electronic devices during TCSM operations




Non-linear screening detector


√ Detection of prohibited electronic devices (including voice recorders, mobile telephones, SIM-cards, digital memory devices), as well as fire weapon. 

√ Detection of improvised explosive devices (IED electronic control systems) in cabin baggage and on the “operator’s” body on the background of complex industrial disturbance from the town development.





professional nonlinear junction detector

NEW version of NR-µ-SV

√ Search for electronic means of communication (SIM cards, miniature audio-recording devices, cell phones, radio stations) in places where their usage is prohibited (predetention centre, places of detention);

√ Identification of means of communication (cell phones, radio stations) and other radioelectronic devices, regardless of their functional status "on / off" in a watchdog or standby mode.




Multi-zone Non-linear Junction Detector


Detector is intended to reveal and localize certain places at the person (upper & low part of the human body) where some miniature radio-electronic devices (MRED) can set or concealed: audio- and videorecorders, communication units, improvised explosive device parts or components and etc.