I would suspect you'd have better luck with electromagnetic focus in an antenna.
Maxwell's equations define radio waves and antennas and how they work.
I have piezo disks and they almost certainly fail as antennas.
It would be a different story if you were trying to use them as microphones which they do very well as.
Every little vibration, boy do they pick them up well. On the other hand the high dielectric constant means that many ceramics are very useful for the size reductions they make possible with antennas. They may be subject to phenomena quite similar to piezo effects, but they are not piezoelectric. The biggest and most long distance piezo effect I have ever seen was during the huge earthquake in Eureka California in the 1980s. It was a very large earthquake, and its a miracle more people were not killed or injured. Only one person was, a bank manager who was traveling in his car wityh his family. During the earhquake very bright flashes lit up the early morning sky very brightly. It was thought that these blue-green flashes may have been caused by tremendous piezoelectric charges.. In the surrounding mountains which contained a lot of quartz.. But who knows.. ? Similar flashes have been seen during other earthquakes and are shown on youtube.
Okay now I have reada bit more about this ide but not the actual paper yet. Who knows, I am curious what other people here think.
This is called a small antenna because of the very large wave length. Because of this, this doesnt seem to fit in to what I know so far. But who knows.. The people at SLAC are physicists who do high voltage stuff for fun.. too.
Is there anyone DIY piezoelectric antenna?reference:https://hackaday.com/2019/04/16/piezoelectric-antennas-for-very-very-low-frequencies/