Tapered CPW Transmission Line for Enlarging Dynamic Range of Transmission Spectroscopy

We propose a new coplanar waveguide (CPW) technique to enhance transmission efficiency and field interaction through a biological sample in two-port transmission line measurements. The aim is to overcome low dynamic range and enlarge parametric sensitivity in dielectric characterization. The new design consists of a CPW line with adapted dimensions in its sensing region to obtain a loaded characteristic impedance of 50 $\Omega$. Glucose measurements show improved distinguishability in concentration. Furthermore, the transmission shows lower ripple at low frequencies (1-4 GHz) and improvement of 4 to 7 dB at higher frequencies (5-10 GHz) for our board loaded with PC12 cell suspensions. In addition, lower reflection is observed.