PC based dielectric constant measurement of solid material (rubber) at x-band

摘要

A microwave bench operating in the frequency range 8-12GHz (X-band) is used to measure the dielectric properties of solid materials. In the present work, Personal Computer (PC) based automatic measurement technique, the stepper motor move the probe of slotted section of microwave bench. Width at the twice minima method is used for measurement of free space wavelength (λ_o) and guide wavelength (λ_g). The forward or backward rotation of the motor, first minima and second minima are controlled through PC. The positions (starting or ending) of probe are sensed by an optical sensor (MOC 7811). The "C" language programming is used for this technique. PC based measurement technique moves probe of the slotted section through 0.00625 mm per step when the stepper motor is operated in full stepping mode and 0.003125 mm when the stepper motor is operated in half stepping mode in forward or backward direction. This technique gives the better accuracy than manual movement of probe (i.e. 1mm)