Index IntroductionGtem cell designTheoretical considerationsResults and discussionConclusionAbstract—A miniaturized Gigahertz transverse electromagnetic cell (GTEM) is designed and fabricated to generate uniform electrical energy (E- ), essential for studying the effect of RF exposure on tissue-equivalent liquids at Global System for Mobile (GSM) communication frequencies (914 MHz and 2.10 GHz). The simulation procedure is discussed and its results are compared with the measurement data. The E-field intensity inside the GTEM cell is scanned using a microstrip-based E-field probe, and the complete uncertainty evaluation procedure is discussed. Theoretical, simulated, and measured E-field strengths are reported with expanded uncertainty. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an original essay Keywords: electronic field probe, GTEM cell, microstrip, RF exposure, uncertainty Introduction A Gigahertz transverse electromagnetic cell (GTEM) is fabricated to generate uniform computable electric field strength (E-) to study the effect of exposure to RF on tissue-equivalent liquids [1]. The GTEM cell design is optimized for 914 MHz and 2.10 GHz, the two most commonly used communication frequencies in India. The GTEM [2] cell design is simulated on HFSS [3], which is based on the well-known numerical method for electromagnetic problems - Finite Element Method (FEM). A dual-band microstrip E-field probe is used to measure the E-field strength. Probe performance is comprehensively characterized; details are provided in [4]. This paper collects the results of measurements made for the E-field intensity. The fitting conditions and the E-field intensity at different positions and with different power fed into the GTEM cell are provided. For measurement validation, another commercially available isotropic E-field probe is used and the results are compared. The analytical value of the field strength E is calculated and reported. Design of GTEM Cell The designed prototype of GTEM cell is shown in Fig. 1. Aluminum is used to fabricate the shell of GTEM cell and copper is used for the inner conductor, i.e. the septum which is supported by a coating of Teflon. An N-type connector is used to provide power to the cell. The connector pin is connected to the septum and the cell housing is grounded to the connector. The septum is supported by the top sheet with microwave-transparent Teflon rods to avoid sagging with the current length in the z direction. A commercially available 4 cm pyramidal microwave absorber is used to match the cell impedance and termination. The cell design parameters are shown schematically in Fig. 2 (ab). The use of copper supported by a Teflon coating is suggested to suppress the generation of higher order modes due to multiple reflections directed from the septum itself. The septum effect is studied using simulation results. The tapered shape of the GTEM cell ensures a characteristic impedance of 50Ω along the direction of propagation. From [1] it was understood that the design parameters are theoretically optimized for the frequency ranges of the GSM band. Therefore, it is deemed suitable for our purpose and the design is used to fabricate the cell for GSM band studies and also for Universal Mobile Telecommunications Systems (UMTS). In scope.
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