Stacked patches with a slot in the common wall for single- and dual-band operation

A two-stacked-patch configuration is considered in which the coupling region is moved from the edges to the center by cutting a slot in the lower patch. Measurements show that, under certain conditions, the coupling between the patches is mainly governed by the slot length, which can be easily adjusted to provide different levels of coupling and hence different values of the ratio f/sub 1//f/sub 2/ of the two resonance frequencies. This approach has been used to achieve antenna designs with both small ratio for moderate enhancement of bandwidth and relatively large ratio between center frequencies (f/sub L1//f/sub L2/=1.3) of a dual-band antenna for the Global Positioning System. Experimental results show that the ratio between the two resonances of a stacked patch antenna can be easily controlled with a slot in the lower patch provided that the slot is the major source of coupling between the patches. For electrically thin antennas, this configuration has the advantage of lending itself to analysis methods based on the cavity model or using a 2-D Green´s function such as the boundary integral method.<>