Design of Fractal- Based Bandstop Filter for Microwave Radiation Leakage Reduction
Engineering and Technology Journal,
2017, Volume 35, Issue 1, Pages 16-23
AbstractThere is a continuing concern over the risks associated with the use of microwave ovens because of the probable effects of the radiation leakage on the health of the individuals. In this paper, a new microstrip bandstop filter BSF is presented, designed and measured as an attempt to reduce the radiation leakage from the domestic microwave ovens operating at 2.45 GHz. The proposed BSF is composed of fractal based open-loop resonators coupled with an open-stub transmission line. The open-loop resonators are in the form of modified Minkowski fractal geometry of the 1st iteration. The open stubs have been adopted to increase the selectivity of the filter stopband response. The suggested filter is designed at 2.45 GHz. Modeling and performance assessments of the proposed filter have been evaluated by means of the computer software technique CST Microwave Studio and the Sonnet EM simulator. Simulation results reveal that the modeled filter offers stopband response with high selectivity. A prototype of the proposed filter is fabricated. The size limitations of the microwave oven opening width have been taken into account. Good agreement has been found between measured and simulated results. Four arrays of such a filter have been implemented to cover the microwave oven door frame taking into consideration the opening dimensions such that it well fit it. Measured radiated electric fields from the oven show that it considerably reduces the leaked radiation. By suitable choice of substrate material and carrying out the required dimension scaling, the proposed design idea is flexible and can be generalized for use with a wide variety of microwave equipment in which microwave leakage represents a serious issue.
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