A new kind of probe for measuring the charge, size and distance of a passing object has been simulated, built and calibrated previously [1]. The probe consisted of a circular inner sensor, surrounded by an insulator, and an outer ring. In this geometry, two different current signals were induced to the sensors as a charged object passed by. By integrating the signals over time, the induced charge could be obtained. The charge, size and distance of the object were calculated from the amplitudes and widths of Gaussian curves fitted to the data. However, calibrating the new probe with charged spheres pointed out some weaknesses. Unlike in the simulations made with Comsol Multiphysics, the speed of the object could not be calculated since the Gaussian peak width data proved to be poor. Moreover, all the simulations and testing were done with objects passing the axis of the probe. If the object passed the probe asymmetrically, the calculations gave false results. According to the new simulations, the poor Gaussian width ratio, which is required for more reliable calculation, can be improved by using a larger outer ring. The displacement problem can be solved if the outer ring is split vertically into two adjacent parts. This way the outer probe tells how much the object is aside from the center. We present simulation results obtained by varying the probe geometry.