Cavity-backed slot array antenna with backward excitation

The slot array antenna with backward excitation is promising as a constituent element of a planar multisector antenna. This paper deals with a slot array antenna with backward excitation that prevents radiation into the backside by installing a cavity. With a view to simplifying the fabrication process, all slots in the array share one cavity. A design guideline is discussed for reducing mutual coupling between the elements. It is found that the cavity width should cause the TE10 mode to be cut off. For a four-element array with a cavity satisfying this condition, the characteristics are evaluated by the spectral domain moment method. It is shown that a beam tilt toward the end fire direction can be obtained, similarly to the case without a cavity. The antenna characteristics are evaluated in terms of cavity length and depth. It is demonstrated that the effect of the cavity length on the antenna characteristics is significant and that the cavity thickness can be reduced. Further, a test experiment is conducted at 19 GHz to confirm the validity of the numerical study. (C) 2002 Wiley Periodicals, Inc.