A very familiar example of a currently available heating source is the domestic microwave oven that is often used to reheat food. In today’s appliances the RF energy is typically provided by a legacy microwave tube: the magnetron. The main limitation of the magnetron is it’s limited ability to adjust it’s output power especially in a changing environment. It’s really a brute force way of heating. Another limitation of magnetrons is that the output power degrades over time and especially in industrial applications this can require expensive maintenance and replacement.
Solid state generated RF power on the other hand has much better control, it’s very robust and barely degrades over time and it has become economical to implement. This added controllability is really the core advantage of the new technology. It enables a number of improvements for existing RF powered applications, and at the same time is also enabling a host of new ones like plasma lighting, medical treatments or automotive ignition.