In this style of treatment the positive and negative sides of the electrode are connected by a constant wire.

It is easiest thought of as a coil. But is most commonly applied through a single electrode (see further down this page)

As a coil it is wound around the limb with positive at one end and negative at the other.

But it is more commonly applied through a single electrode containing a coil an example from Enraf Nonius is shown below:

In these applicators (available in different sizes and shapes) there is a coil of wire that creates the current.

Seen from the side the field looks like this:

This type of shortwave application has become very popular due to it’s ease of use.