Nonlinear junction detector
Encyclopedia
The non-linear junction detector, or an NLJD, is a device that illuminates a small region of space with high-frequency
, RF
energy. Any "non linear junction" in the vicinity—for example, and particularly, the p-n junction
-- will receive this energy, and because of the non-linear nature of the junction, it will rectify it, re-emitting some of it on multiples of the illumination frequency (see harmonic
). The detector has a sensitive receiver
tuned for these harmonics, as well as appropriate processing and displays to make their presence known to the user of the device.
Since the basis of almost all semiconductor
electronics
is the p-n junction, an NLJD is correspondingly capable of detecting almost any un-shielded electronics, whether the electronics are on or off. It can also detect things that are not themselves electronic in nature, so the use of the device requires a modicum of skill and experience.
Frequency
Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency.The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency...
, RF
Radio frequency
Radio frequency is a rate of oscillation in the range of about 3 kHz to 300 GHz, which corresponds to the frequency of radio waves, and the alternating currents which carry radio signals...
energy. Any "non linear junction" in the vicinity—for example, and particularly, the p-n junction
P-n junction
A p–n junction is formed at the boundary between a P-type and N-type semiconductor created in a single crystal of semiconductor by doping, for example by ion implantation, diffusion of dopants, or by epitaxy .If two separate pieces of material were used, this would...
-- will receive this energy, and because of the non-linear nature of the junction, it will rectify it, re-emitting some of it on multiples of the illumination frequency (see harmonic
Harmonic
A harmonic of a wave is a component frequency of the signal that is an integer multiple of the fundamental frequency, i.e. if the fundamental frequency is f, the harmonics have frequencies 2f, 3f, 4f, . . . etc. The harmonics have the property that they are all periodic at the fundamental...
). The detector has a sensitive receiver
Receiver (radio)
A radio receiver converts signals from a radio antenna to a usable form. It uses electronic filters to separate a wanted radio frequency signal from all other signals, the electronic amplifier increases the level suitable for further processing, and finally recovers the desired information through...
tuned for these harmonics, as well as appropriate processing and displays to make their presence known to the user of the device.
Since the basis of almost all semiconductor
Semiconductor
A semiconductor is a material with electrical conductivity due to electron flow intermediate in magnitude between that of a conductor and an insulator. This means a conductivity roughly in the range of 103 to 10−8 siemens per centimeter...
electronics
Electronics
Electronics is the branch of science, engineering and technology that deals with electrical circuits involving active electrical components such as vacuum tubes, transistors, diodes and integrated circuits, and associated passive interconnection technologies...
is the p-n junction, an NLJD is correspondingly capable of detecting almost any un-shielded electronics, whether the electronics are on or off. It can also detect things that are not themselves electronic in nature, so the use of the device requires a modicum of skill and experience.
External links
- Non Linear Junction Detector Review and Tutorial
- http://www.google.com/patents?id=3QgEAAAAEBAJ&dq=patent:6057765
- Example of Modern Non Linear Junction Detector