How would this neutrino beam work, as there is no feasible material that can really focus these particles? Won't a neutrino emitter (the sort we can build) be e

How would this neutrino beam work, as there is no feasible material that can really focus these particles? Won't a neutrino emitter (the sort we can build) be essentially isotropic. Perhaps higher-energy neutrinos would have a higher interaction cross-section, making them somewhat more 'visible'. Long wavelength radio (near 3-20Hz) may work just as well, with potentially a better data rate (still poor) than a neutrino-encoded emitter. A "neutrino emitter" would have no 'gain', while we may find ways to build really large and orientable radio antennas. You can build an antenna that can work on wavelengths larger than the earth with very long wires strewn out into outer space. Although below 3 or so Hz, space plasma becomes opaque and that would prevent transmissions.