Radio frequency spectroscopy apparatus and method using multiple

Abstract

An apparatus and method for measuring the concentration of a chemical substance in a test sample based on a technique of waveform distortion analysis is disclosed. The apparatus includes a waveform generator that generates a periodic electromagnetic signal having a plurality of frequencies simultaneously present. Preferably the signal has a fundamental frequency and simultaneously present harmonic frequencies which shape the waveform. The shaped periodic signal is transmitted through the test sample by a probe assembly which also receives the transmitted signal from the test sample. Propagation of the shaped signal through the test sample results in a change in the waveform shape or distortion by the chemical, and a detector circuit is provided that quantifies the change in shape of the signal to determine the concentration of the chemical in the test sample. The harmonics producing the waveform shape and the fundamental frequency of the signal are both selected so that the change in shape of the signal is particularly responsive to the presence of a selected chemical substance. The magnitude of the distortion or change in shape of the signal can be directly correlated to the concentration of the selected chemical substance.