A material constituent sensor includes one or more metamaterial assisted antennas located to probe a material that may be a multiphase composition. A signal source excites at least one metamaterial assisted antenna in a desired range of radio frequency (RF) signals, a desired range of microwave signals, or a combination RF signals and microwave signals. A data processing device is programmed to estimate material constituent fractions associated with the probed material based on amplitude data, phase data, frequency shift data, or a combination of amplitude data, phase data and frequency shift data in response to transmitted energy from at least one excited metamaterial assisted antenna, reflected energy received by at least one metamaterial assisted antenna, frequency shift data, or a combination of the transmitted energy, the reflected energy and the frequency shift.