Comparison of Theoretically Simulated and Experimental Scattering Matrix Parameters in a Five Port Transmission Line Frequency Multiplexer for Solid State Nuclear Magnetic Resonance Techniques

Radio frequency (abbr.: RF) techniques constitute a very useful tool in studies on biologic and chemical systems, therefore it is employed in Nuclear Magnetic Resonance (abbr.: NMR) techniques. In order to make use of it, there is a need of designing and modelling of NMR probes. These NMR probes exemplify single-or multi-port radio frequency multiplexers. The NMR probe undergoing analysis is comprised of an impedance tuned and matched coaxial transmission line network terminated with a single sample coil, and multiple RF input-output connections adapted to 50 Ohm standard by means of tuning and matching capacitors. The comparison of scattering matrix elements S(i,i)(reflection coefficients) of both theoretically simulated and constructed a five channel transmission line frequency multiplexer probe of J.Schaefer & R.McKay type is presented. The S-matrix transmission coefficients: S(i,j), i≠j, are presented for a "real" multiplexer only, due to the importance of the real NMR probe performance. So called calibration spectra obtained with the multiplexer probe are shown as well.