Nonlinear locators (NLJD for short) are designed to search for semiconductor elements that are part of various electronic devices, such as bugs, microphones, video cameras used for wiretapping and unauthorized removal of information. They can be located in the wall, the upholstery of a chair, under clothes, in a bag, among the debris. To solve each unique case, different models of nonlinear detectors with certain characteristics, such as the frequency of the probing signal, or an operating distance are required.

The functioning principle of non-linear junction detectors is based on the re-emission by a semiconductor, or more precisely, by a p-n junction, of an electromagnetic wave at the second and third harmonics. Semiconductors in the world around us can be divided into two groups: natural (corrosion) – formed as a result of natural processes and artificial – man-made, which can include components of any modern electronic devices. Natural semiconductors re-emit an electromagnetic wave at the third harmonic, and artificial ones at the second harmonic. The action of nonlinear locators is based on this difference. By the level of the signal received by the locator on each harmonic, it is possible to determine whether there is a bug hidden in the thickness of the wall in front of us or it is just rust.

Non-linear detection devices are the only equipment that provides detection of an electronic device, regardless of whether it is turned on or off, i.e. when it is, even in a de-energized state.

Non-linear detection equipment is designed to locate semiconductors with their subsequent selection for artificial (electronic) and natural (metal corrosion) semiconductor elements.

There are two main groups of semiconductors (nonlinear transitions): artificial and natural

Artificial semiconductors are diodes, transistors and microchips that are used to make up various electronic devices.

Natural semiconductors are the so-called MOM (metal-oxide-metal) semiconductors. which are widely represented in nature (a typical example: rust - iron dioxide) and whose nonlinear transition is formed between metal elements in contact with a film of oxides on the surface.

Artificial and natural semiconductor elements have different physical characteristics, in particular, the function describing the non-linear junction of an artificial semiconductor has an asymmetric quadratic form in contrast to the symmetrical form of a natural semiconductor.

The most important characteristic of a natural semiconductor is its unstable nature in time, unlike an artificial semiconductor, in which the parameters of non-linear junctions are constant, not changing in time.

In practice, when mechanically acting on a semiconductor, artificial non-linear junctions do not change their characteristics, and natural non-linear junctions are unstable, collapsing and being created again.

The most accurate recognition can be carried out using the following characteristic difference between artificial and natural semiconductors. Artificial semiconductors have a static structure in time, because they have a fixed rigid structure of nonlinear transitions, and a natural semiconductor, on the contrary, has an unstable structure of its nonlinear transitions.

In particular, when the search object is mechanically affected (for example, with a rubber mallet) MOM semiconductors change their characteristics, because some individual nonlinear elements will be destroyed, and others will be created, so the operator will hear a characteristic change in noise (crackling) in response to mechanical action.

When using a non-linear junction detector with a spectrum analyzer under mechanical action, the operator will see changes in the spectrum with a MOM semiconductor and the stable nature of the spectrum with an artificial semiconductor.

In practice, the objects of the search are semiconductor elements with unknown haracteristics. We don't know where and how they are hidden, how they are shielded. Depending on the power and frequency of the probing signal, non-linear detectors are able to find both micro components (microchips, SIM cards) and large objects, such as metal components of an IED at a distance. Therefore, we use different models of LORNET in different situations. Unfortunately, none of the existing NLJDs in the world can claim 100% efficiency. That's why we always say that most of the search tasks are solved only through your eyes.

Until 2008, this range was the main range of all non-linear detectors. However, with the development of microminiaturization of electronic devices, the appearance of SIM cards, more and more devices began to appear that the nonlinear locator cannot detect due to the frequency of the probing signal used. Currently, this range remains relevant only when working in conditions of high humidity.