Rectangular Cavity Sensor for Distinguishing Between Normal and High-Drivability-Index Gasolines

Abstract

The Drivability Index (DI) of gasoline is a measure of fuel performance of engine operations. Therefore, distinguishing a gasoline of specific DI in advance is useful for improving engine efficiency and maintenance. We consider the problem of distinguishing between normal gasoline and HiDI (High DI) gasolines and propose an electromagnetic wave-based rectangular cavity sensor. For commercialization, it is designed to have a simple structure and basic resonance mode TM110 in the common frequency range of 5 GHz to 6 GHz. The proposed sensor has a simple structure of monopole radiating electromagnetic waves and a metal rectangular cavity containing gasoline samples. By considering one commercial normal gasoline sample of permittivity 2.157 and five HiDI gasoline samples of permittivity in the range of 2.018 to 2.218, we obtain 11.5 MHz resonance separation at room temperature to the closest HiDI sample from the simulation and 8 MHz resonance separation from the fabricated sensor experiment. To verify the feasibility of the fabricated sensor under temperature variation from 0°C to 20°C, we derived a simple linear distinction function of resonance frequency and S11 parameter and obtained a minimum 4.4MHz resonance separation. These results showed that the distinction performance for normal gasoline is robust to temperature variations. Furthermore, we showed that the distinction property is robust to design parameter errors, installation position variations and sensing time variations. These results show that the proposed sensor can be utilized effectively for distinguishing normal gasoline.