A Scanned Flush-Mounted Multimode Slot Antenna

摘要

The report describes the electrical characteristics of a multimode slot antenna that has a scan capability. The antenna consists of a rectangular slot with a onewavelength aperture, excited with an offset probe, that couples energy into the desired TE sub (10) and TE sub (20) rectangular waveguide modes. This combination of modes produces a beam that is tilted from the slot broadside. The resultant beamwidth is narrower than that of a comparable slot excited in the dominant mode. The beam shape and scan angle depend on operating frequency and relative excitation of the two modes. A slot was mounted axially on a circular cylinder, and pattern, gain, and VSWR measurements were performed at L/S band frequencies for both air-filled and dielectrically loaded configurations. (Author)