Microwave oven cavity excitation system employing circularly polarized beam steering for uniformity of energy distribution and improved impedance matching

An excitation system according to claim 5, which further comprises:

• a feed waveguide extending along the outer surface of said one wall of the cooking cavity, one wall of said waveguide being common with at least a portion of said one wall of the cooking cavity, and said feed waveguide serving to convey cooling airflow in addition to microwave energy;
• a microwave energy generator coupled to said feed waveguide to establish a mode therein;
• said feed points being coupling apertures in said common wall spaced longitudinally along said feed waveguide;
• a variable phase shifting element in the form of a rotatably-mounted dielectric vane positioned in said feed waveguide so as to be rotated by airflow therethrough and so as to vary the relative phases of microwave energy coupled from said generator to said coupling apertures.