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One of the recent problems for pacemaker (PM) patients is an anti-shoplifting system which is called the electronic article surveillance (EAS) system. Electromagnetic field patterns of the two types of EAS system, radio frequency (RF) and electromagnetic (EM) systems, are simulated with in Irnich model which consists of saline and a pacemaker. The voltage differences induced between a PM casing main body and the tips of pacing leads and those between both leads (ventricular and atrium) are estimated. The voltages induced between PM body and the ventricular lead are about 300 mV and 1 mV by RF and EM systems, respectively. Considering the input characteristics of the PM circuit, these voltages will not bring about serious errors in the PM system if the patient goes through the EAS gate at a normal pace. Acousto-magnetic EAS systems which use lower frequencies may be more harmful to the PM system.

Hypothermia is proposed as a treatment for hypoxia-ischemia in newborn infants who suffer serious cerebral injury or die, if they are brought back early. In this treatment the deep brain temperature monitoring which is noninvasive and continuous is required. Multifrequency microwave radiometry (MWR) is one of the promising candidates for that purpose, and we have been developing a five-band microwave radiometer system and appropriate data processing methods. This paper is to describe the current status of a newly designed MWR system which operates in a normal room with various electromagnetic background noise. Temperature resolutions of the five receivers were obtained by a calibration experiment using a temperature-controlled water-bath. The results of a temperature retrieval simulation experiment is also presented.

Recent simulation studies have shown that a technique of multi-frequency microwave radiometry is feasible for non-invasive measurement of deep brain temperatures in the new-born infants. A five-band microwave radiometer system has been developed, and its operation in a normal electromagnetic environment is checked. Five receivers operating with a waveguide antenna and at center frequencies of 1.2, 1.65, 2.3, 3.0 and 3.6 GHz (0.4 GHz bandwidth) are calibrated using a temperature-controlled water-bath. Temperature resolutions obtained for each receiver are 0.183, 0.273, 0.148, 0.108 and 0.118 K, respectively. A temperature retrieval simulation based on these resolutions and the previously proposed algorithm shows that the confidence interval, as produced by thermal noise, is 0.62 K for the retrieved central brain temperature. If the conductivity of brain is estimated wrong by 10 %, this will result in an error of 0.3 - 0.4 K. The result of this work is encouraging for realization of radiometric measurement of temperature profile in a baby's head.