An array technique for reducing ground losses in the HF range

Ground losses of HF antennas situated near the earth's surface are reduced if single antennas are replaced by small arrays of, for example, two or four closely spaced radiating elements. It is shown both theoretically and experimentally that an array spacing of
\sim 0.1 \lambda
is sufficient to achieve significant improvement in ground-to-ground transmission efficiency. In particular in the lower HF range and for poorly conducting ground, the improvement approaches a theoretical limit equal to the number of elements in the array.