Simple RF matching circuit for conversion of electrosurgical units or laboratory amplifiers to hyperthermia treatment...

An inexpensive combination RF matching network and power meter circuit is described for matching a broad range of load impedances to an arbitrary source impedance and providing accurate indication of net real power delivered to the load. A schematic is included with component values calculated for an operating frequency of 500 kHz. Specific design equations are given to facilitate frequency or impedance scaling. While general in nature, the matchbox design is intended for safe use with any generator capable of 100-250 W of continuous wave power at an operating frequency between 0.1-10 MHz for inducing localized hyperthermia of biological tissues. Capacitively or resistively coupled RF current heating then may be accomplished using a wide variety of electrode configurations, depending only on tumor geometry and not on matching considerations.