A refrigeration lubricant composition contains an ester compound obtained from a polyol and a fatty acid, and a five- or six-membered ring cyclic ether compound having a side chain with an ester bonding. A first dielectric and a second dielectric are sandwiched between the ground plane and the radiation element, in a side-by-side relationship. Each leaf of the stack has a leaf section which maintains wiping contact with one of the components and a root section which is fixed relative to the other component and from which the leaf section extends.