The overall aim of the proposed Phase II program is to complete the development and evaluation of a self-calibrating, low-cost Handheld Digital Microwave Radiometer that can non-invasively measure subsurface temperatures by simple contact with the human body in order to detect and locate subsurface inflammations. In addition to its use as a contact thermometer for core temperature measurement, promising applications for the Radiometer include detecting infections around post-surgical wounds or implanted devices, locating malignant tumors that cause local temperature increases in subcutaneous tissues, evaluating vascular insufficiencies and inflammatory diseases such as arthritis, and determining the efficacy of treatments for these diseases. The novel architecture of the Radiometer will be implemented using miniaturized microwave components including recently available silicon-germanium microwave transistors for low-noise amplifiers and a high-gain logarithmic amplifier/detector integrated circuit that drastically reduces the gain required to amplify temperature-generated noise to adequate detection levels. A novel low-loss resonant switch using microwave field-effect transistors has been developed to simplify the digital calibration process without the added noise or excessive loss of other available miniaturized switches. The digital calibration and measurement technique developed and proven in previous cabinet mounted digital radiometers will be adapted and used in the proposed Radiometer which will be tested in a specially developed tissue-equivalent 3-D phantom capable of simulating clinically interesting subsurface temperature profiles, and the results will be used to finalize the design of a prototype instrument suitable for laboratory testing leading to a final design suitable for clinical testing. Contacts with manufacturers will be established with the aim of early commercialization. Unlike conventional thermometers, the Handheld Digital Microwave Radiometer will conveniently, quickly, and non-invasively measure subsurface temperatures. The Radiometer will provide new means of locating infections and lesions because of the ability to estimate a temperature-depth relation. The effectiveness of treatments can be quantified by monitoring changes of internal temperatures with medicines or procedures. [unreadable] [unreadable]