Improvement of UWB patch transducer properties applicable for fetal monitoring system

摘要

The great potential application of wireless body network (WBN) to improve the quality of healthcare service to people was evaluated to incorporate the ultra wide band (UWB) technology to obtain the better performance of WBN stuff functionality. One of the very challenging WBN device developed is specifically applied for fetal monitoring. The designed fetal monitoring was intended for specifically applied to suitable utilized by the risk pregnant woman who has the difficult access to the hospital. Despite the many risk factors existed during the pregnancy the constructed UWB fetal monitoring system is designed to capable for sensing the fetus heart rate variability, the fetus growth and its contraction. The numerical evaluation performed was mainly focused to assess the electrical properties of the designed UWB transducer to meet the technical specification required. In practice, the transducer is in the form of patch antenna structure. The antenna was designed using the basic structure of dielectric/ substrate which consists of FR4- Epoxy material, top conducting radiator and ground. This antenna is connected by edge feeding technique that set SMA connector on the side of the dielectric material. A number of significant electrical properties improvements of the designed UWB patch transducer were found during the numerical computing stage including the radiator/transducer pattern, the S11, VSWR, and the gain. Through the numerical assessment it is clearly shown that the return loss (S11) is very excellent to reach the value of approximately -35 dB. Considering the S11 boundary of -10 dB value the constructed RF-waves radiating transducer is working well at the frequency range from 1.3 GHz up to 4.1 GHz (equal to the bandwidth 2.8 GHz). The best VSWR value obtained during the RF transducer numerical design is approximately 1.12. The gain achieved is 2.61 dB. The advanced fetal monitoring development will also utilizes the incorporation of the robust image processing - echnique to plot the woman pregnancy indicators on the display unit.