until it reaches the wet soil where nearly all of the power is absorbed in the first 10 cm of the wet soil which is the active heating zone the ability to couple energy into a narrow area has several advantages including the enhancement of the rock 39 s intrinsic permeability and the generation of steam once all of the water and hydrocarbons have been removed by microwave heating in the region between the antenna and the phase boundary the power intensity can be calculated as a function of distance in the dry soil as illustrated in fig7 nearly 15 percent of the power being radiated by the antenna is still available to heat the water and oil at 10 meters with 2 megawatts of power radiating from the subsurface antenna approximately 30 kilowatts of power is available for heating at this distance only the permittivity of dry soils comprised of aluminum silicates and quartz were measured in the laboratory however microwave heating of selected natural minerals were performed by mcgill and walkiewicz 1987 and are presented in the following table it is possible to estimate the adsorption of microwave energy by comparing the permittivity measurement with the results presented by mcgill and walkiewicz 1987 aluminum silicates such as albite and orthoclase show only minor.