A helix antenna was presented together with low power RF amplifier, as the frequency fitted, the axial direction can obtain largest radio energy.

The second is the measurement of arrival direction for radio signals, which is to monitor the spatial distribution of radio energy, which is often called spatial spectrum estimation.

The process is not entirely efficient, and there is a byproduct: an enormous amount of energy — radio waves, X-rays and regular light — hyper-illuminates the whole scene.