Coaxial Power Systems Ltd manufacture range of styles of impedance matching network to link the load to the RF generator. The purpose of the network is to adjust the input impedance of the load to 50 Ohms so that maximum power is transferred from the generator, whose output impedance is 50 Ohms, to the load.
Coaxial Power Systems Ltd. manufacture two types of network - Manual and Automatic.
Manual Matching Network Products
The manual matching network consists of two adjustable air vane capacitors and a fixed inductor, which are usually arranged as an "L" network. (The arrangement can be simply converted to a "Pi" network if required). Geared drives with vernier dials are used to adjust the capacitors for minimum reflected power as displayed on the generator reflected power meter. When the reflected power is zero, the system is "tuned" and all of the power output of the generator is being fed to the load.
Automatic Matching Network Products
The automatic matching network is similar to the manual version except that servomotors drive the capacitors. At the input of the network, a phase and magnitude detector determines the position of the capacitors. This information is transferred to the separate controller. The controller then drives the servomotors to the positions, which give zero, or minimum reflected power.