Antenna tuner

A matching network (also matching ) is a circuit for matching the impedance between a source of high-frequency signals (for example, high-frequency generator ) and a load such as an antenna in electrical engineering. Matching networks between a radio unit and an antenna are also referred to as an antenna, tuner and improve transmission and reception characteristics. Using this unit as the electrical length of the antenna is changed, without changing the mechanical length. Similar matching networks are also used in other applications of high frequency generators, such as used in plasma etching.

The circuit, refer switchable or variable reactance ( inductors and capacitors - nearly lossless transformation, rarely Resistors - lossy transformation). The construction can be done in various circuits. Frequently circuits such as the Pi circuit used with resonant transformer. In addition to the improved matching can be achieved by such circuits is also a reduction of the harmonics.

By manual or automatic variation of the component values ​​, such as when using the variable capacitors, it is achieved that the transformed impedance of the antenna to that of the corresponding radio. Is an impedance transformation. This adjustment is usually narrow band and must be re-adjusted for changed frequencies.

In particular, for a good transmitter adjustment is necessary. Mismatch will cause a portion of the transmission power is reflected and has to be destroyed as a heat in the transmitter or the power amplifier. The aim is therefore to offer the sender a standing wave ratio as close as possible 1. This problem is not present in pure receivers. Here, there is the benefit of the matching of a higher signal level at the input of the receiver.

Antenna tuners are sometimes simplified as a tuner (not to be confused with the reception circuit ) respectively.