Long Distance Signaling Using Axion-like Particles

The possible existence of axion-like particles could lead to a new type of long distance communication. In this work, basic antenna concepts are defined and a Friis-like equation is derived to facilitate long-distance link calculations. An example calculation is presented showing that communication over distances of 1000 km or more may be possible for $m_{a}< 3.5$ meV and $g_{a\gamma \gamma} > 5 \times 10^{- 8} {\text{GeV}}^{- 1}$.