Abstract: The microwave apparatus for processing dielectric materials includes a number of tunable cavity devices arranged vertically one above the other, each having a movable piston. Dielectric conduit means extend downwardly through all of the cavity devices, passing through the various movable pistons. Each tunable cavity device has a microwave generator associated therewith so as to supply controlled amounts of power at frequencies depending upon the type of material being processed. The processing is monitored by additional cavity devices, each having a movable piston. Whereas the pistons of the power cavity devices are positioned so as to cause the material being processed to absorb a maximum amount of microwave power, the pistons in the monitoring devices are positioned so that a detectable amount of power is reflected. The amount of reflected power is indicative of an electrical characteristic, such as moisture.

Abstract: A slotted radiating unit is lowered into a well casing of limited cross section, and microwave energy is fed downwardly thereto via a transmission line also installed in the casing. Two embodiments of the radiating unit are disclosed, and two embodiments of the transmission line are also described. Depending upon the subterranean conditions, periods of on and off microwave propagation are sometimes employed; in some instances dual radio frequencies are utilized to enhance petroleum flow. Subsurface sensors are made use of to control the ground level radio frequency generator (or generators).