| 摘要 |
An antenna (20) is formed of a two-dimensional array of radiating apertures disposed in rows (22) and columns (24), each of the radiating apertures being formed as slots (40) within a top broad wall (28) of a waveguide (26). The width of the broad wall is many times greater than the height of a sidewall (32, 34) of the waveguide, the waveguide having a rectangular cross section. A wave launcher (56) connected to a first end wall (36) of the waveguide launches a higher-order mode of electromagnetic wave wherein the order of the mode is equal to the number of columns of the radiating elements. The top broad wall (28) has an enlarged thickness of approximately one-eighth free-space wavelength. Each of the slots extends via a passage (46) from an input port (48) at an interior surface (52) of the top broad wall to an output port (50) at an exterior surface (54) of the top broad wall. All of the slot output ports are centered at the locations of maximum intensity of electric field. In order to provide for magnetic coupling from an electromagnetic wave within the waveguide to longitudinal sides of each slot, each slot passage is inclined so as to displace the slot input port to a location wherein there is sufficient magnetic field component parallel to the slot to couple power from the wave to be radiated from the antenna. Inclinations of successive ones of the slot passages are staggered for coupling from magnetic wave components of equal polarization and phase.
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