The ultra-long wave has a substantially long stroke, hence it is hard to be directional. If it is less directional, the wave can be spread widely. If it is more directional, the wave is sent to the specific range. The ultra-long is notionally least directional, though it can be delivered deeper into the tunnel, which is corresponding to my experience. On the other hand, the ultra-long wave should affect more people within the widespread area, even if it is more specifically irradiated.
When using higher frequencies, it is directional in the nature of electromagnetic wave, though there is a large possibility that those frequencies cannot have an influence on the brain. Or at least, the synchronization cannot be achieved as the brainwave is very low. There is an option to find the alternative frequency to affect the brain, though the real phenomena have been a synchronization triggered by the ultra-long wave.
Having said that, the effect can be directional, if the individual difference is wide enough. It is not so sure how generic the electromagnetic wave works to each person, as the impact looks like quite directional. It means I am affected by the wave but others surrounding me are not controlled by the same wave. It is quite rare occasion that another person is affected by the same frequency, even though it really exists.
The possibility is still open to a different range of the wave, despite the fact the ultra-long is mainly used for the brain control. The ionic resonance occurs at a 1000Hz frequency, where the ion reacts to vibrate against the external electromagnetic wave. This is quite similar to a function of the microwave oven that irradiates a wave to vibrate a stuff to be heated up. The phenomena are the same as the ionic resonance, though the microwave utilizes 2.45GHz, the different frequency.