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This report results from a contract tasking Semiconductor Physics Institute as follows: To achieve the proposed goals, the modeling of the circular waveguide section containing semiconductor obstacle will be performed. To calculate the average electric field in the semiconductor obstacle the finite difference time domain method will be used. Although, the lowest critical frequency in the circular waveguide is characteristic to H11 mode higher modes such as E01 and H01 are also sometimes used. Depending on mode some components of electromagnetic field are suppressed, nevertheless in the vicinity of the obstacle all six components of electromagnetic field might be excited and they should be taken into account when determining averaged electric field in the semiconductor obstacle. Since the resistive sensor actually feels the amplitude of electric field, the distribution of electric field component within the waveguide should have a crucial influence on the performance of the sensor and this fact should be taken into account in sensors design. Therefore it is also planning to investigate the behavior of the averaged electric field in the semiconductor obstacle when different modes are excited in the waveguide. To perform investigation it is planned to use internal programs for the modeling of electromagnetic wave propagating in the circular waveguide with the obstacle. Such modeling has already been done in rectangular waveguide with semiconductor obstacle placed on a wide wall of the waveguide and in the obstacle under the thin metal diaphragm. In both cases all six components of electromagnetic field in Cartesian coordinate system has been determined. It is planned to modify the program so that it should be able to calculate the electromagnetic field components in cylindrical coordinate system., The original document contains color images.

This report results from a contract tasking Semiconductor Physics Institute as follows: The contractor will investigate resistive sensors for measuring high power microwave pulses. At the end of this investigation, the contractor will develop a prototype unit of the coaxial-type resistive sensor and test it in a wide frequency and power range.