A non-linear junction detector, also known as an NLJD, is a type of detector that uses high-frequency RF energy to illuminate a small region of space. It is used in various applications and is a popular detector. Its primary advantage is its low cost, which makes it a good choice for research and development.

Circularly polarized antenna

A Non-Linear Junction Detector is an electronic device that detects the presence of other electronic devices, even when the devices are turned off. The device uses Digital Modulation and Correlation (DM&C) technology for improved detection and minimized interference. The detector operates in the 2.404GHz to 2.472GHz frequency band.

A non-linear junction detector can be used to detect hidden electronic devices, such as surveillance devices. This device emits a 2.4 GHz signal that stimulates non-linear junctions and creates electromagnetic harmonic waves that can be picked up by a receiver. The presence of a surveillance device is detected by a strong response to the second harmonic of the received signal. Non-linear Junction Detectors are ideal for inspection of sensitive areas in buildings and places, such as banks, conference rooms, and companies. The device has a wide frequency range and circularly polarized antenna to detect even the smallest hidden electronic devices.

Multiple antennas

Non-linear junction detectors with multiple antennas are used to measure signal strength in two frequency ranges. The signal strength of each range is displayed on a display unit that is preferably integrated into the antenna head assembly. The display unit also provides the user with operational information about the non-linear junction detector.

The detector operates by detecting the re-radiated signals at two frequencies. One of these frequencies is the first harmonic, while the other is the second harmonic. Using this method, the detector can detect which type of non-linear junction is present.


Non-linear junction detectors are usually based on a method that involves transmitting a signal with more than one transmit power level and receiving its second and third harmonics. These signals are then compared to determine the presence of a non-linear junction. The present invention uses a technique that compares the amplitude of the second and third harmonic signals. This technique is an improvement over prior art detectors that rely on the received signal alone.

A non-linear junction detector can detect third and second harmonics, depending on the threshold level of the signal. It can also detect the presence of noise in an area that is saturated with signals. Depending on the frequency of the signal, the detector can either automatically adjust its transmit power level, or manually select the threshold level.


A non-linear junction detector is a device that can be used to detect electromagnetic fields. The device consists of an array of antennas. The detector is typically mounted on the surface of a structure. The antennas are connected by cable and can be rotated to a desired position. A microprocessor controls the device to send control signals to the oscillators. This allows the detector to be adjusted to avoid unwanted frequency fluctuations and ensure compliance with regulations. The non-linear junction detector can also be controlled via a keypad.

Non-linear junction detectors are not without their disadvantages. First of all, non-linear detectors produce an excessive number of false alarms. This is because of the non-linear behavior of dissimilar metal junctions. This makes it difficult to detect surveillance devices because of the time required to investigate false alarms. Another drawback is that the non-linear detector requires damaging the environment.