I just checked one of Einstein's talks, and the term he used for the aether was "Äther." He was talking about the luminiferous aether (the hypothetical substance in which light is a wave) as opposed to the classical aether (the fifth element that the gods breathed), but I suspect that the word is the same for both. So... "Tesla Ätherische Übertragung GmbH, Bahnhof Brandenburg"?

(I don't actually speak German beyond the ability to partially decode technical papers, so this should be taken with a massive grain of salt)