An antenna apparatus and method for using the same are disclosed. In one embodiment, the antenna comprises an antenna element array having a plurality of radiating radio-frequency (RF) antenna elements formed using portions of first and second substrates with a liquid crystal (LC) therebetween, the first substrate comprising a plurality of irises and the second substrate comprises a plurality of patches, wherein each of the patches is co-located over and separated from an iris in the plurality of irises with LC at least partially between each overlap region a patch and iris overlap; and a reservoir structure between the first and second substrates to hold LC and comprising areas around the RF antenna elements, the reservoir structure having a cavity large enough to accommodate thermal expansion of the LC and having one or more areas void of LC, wherein LC remains in patch/iris overlap regions of the plurality of radiating RF antenna elements even when additional LC could enter the one or more areas void of LC.