Abstract: A meter measures the flow rate of a mixture by measuring a frequency characteristic of microwave propagation within a waveguide which forms a part of the conduit through which the mixture flows. Spaced apart slots in the waveguide form transmitting and detecting antennas which are connected to the output ports of a microwave bridge. An oscillator generates microwaves which are fed to the input of the microwave bridge. The output of the bridge is the difference in power transmitted through the two antennas. This signal is fed to a phase sensitive detection system and the output can be correlated to the flow rate of the mixture. In one embodiment, a computer control unit and computer controlled switches are provided to switch the microwave bridge in and out of the circuit so that both the flow rate and the concentration of an ingredient can be measured.

Abstract: A steerable microwave antenna array having directional characteristics, which includes at least two antenna elements spaced from one another by a predetermined distance, each antenna element defining a controllable directional radiation pattern of a selectable intensity, and having an axis of maximum radiation intensity, and wherein the directional characteristics are derived from the super-position of the radiation patterns, the axes subtending a predetermined angle therebetween, the wherein the improvement provides for feed means connected to each antenna element, each including a photo-conductive element for a selected frequency in the microwave region, so that, upon the photoelectric elements being impinged with a selected intensity of light, the directional characteristics are changed in dependence of at least the difference in the intensity of light impinging on the photo-conductive elements, respectively.