Abstract: A cylindrical waveguide (1) for analyzing a flowing material (18) using guided microwave spectroscopy (GMS). Spaced apart plates (2, 5) each define a plane within the waveguide housing (3) that is parallel to the direction (47) of material flow through the waveguide. Two opposed frames (7, 19) each surround an aperture (6) that permits access to the region between the waveguide plates (2, 5). A microwave probe assembly (81) is mounted at each frame (7, 19) to permit the radiation and reception of electromagnetic waves within the housing (1). A temperature probe (51) is inserted into the interior of the housing (1) via fitting (13). A y-shaped assembly (89) can be used to divide the flow into two separate paths including a diverter vane (93) that permits flow to be equalized within the two separate flow paths.

Abstract: The present invention includes a guided microwave spectroscopy system (1) that eliminates the need for an automatic gain control feature by providing multiple signal processing paths having differing fixed voltage gains. An emitted signal which exits a test chamber (2) containing a material under test is simultaneously amplified by at least a first fixed gain amplifier (4) and a second fixed gain amplifier (7). The output signal of each amplifier is separately digitized and then normalized for further digital signal processing by a computer (13) in order to determine parameters of the material under test which may have variable microwave radiation characteristics that are a function of the frequency of the signal emitted into the test chamber. During the signal processing step a system clock (121) causes the computer to sample only an integral number of complete output signal cycles.