Planar Microwave Sensors for Accurate Measurement of Material Characterization: A Review

In order to get a simple sample preparation, with the accuracy of resonant cavity methods in extracting local material properties, and to make it easily integrate with other microwaves [29], the planar transmission line is the best technique compared to other techniques. [...]these paper studies the recent development for the planar transmission line technique with several designs based on the methods, frequencies, techniques and technologies used in order to produce a highly accurate and sensitive sensor. 2. Conversely, these techniques produced a low quality factor (Q-factor) and poor sensitivity which decrease and limit the use of different materials [32, 33]. [...]a novel structure of planar microwave sensors for determining and detecting the dielectric properties in common solid, sheet, liquid or semi-solid to produce high Q-factor [34] with the capability to suppress the undesired harmonic spurious, has been established by several researchers. 2.1. According to [52], the comparison of three microstrip resonator sensors between the ring, meander and minkowski fractal structures is drawn to determine the dielectric constant of palm oil liquid. According to author(s) [61], they designed a transmission line connected with EBG cells operate at 2GHz.