Abstract: Disclosed is a system and method to aid in these inspections that avoid the disadvantages of the prior art. The system and method are operative to take thickness measurements of, and thus evaluate the condition of, materials including but not limited to refractory materials, operating in frequency bands that result in less loss than previously known technologies, and utilizing a system configuration and signal processing techniques that isolate the reflected signal of interest from other spurious antenna reflections, particularly by creating (through the configuration of the antenna assembly) a time delay between such spurious reflections and the actual reflected signal of interest, thus enabling better isolation of the signal of interest.