Very near ground radio frequency propagation measurements and analysis for military applications

We analyze, using a 2-ray model, the effects associated with placing a man-portable radio transceiver very near the ground (3-28 cm). A significant decrease in signal strength occurs when a soldier drops from the crouched position to the prone position. As much as a 16.8 dB decrease in signal strength was observed. This effect is more pronounced at short ranges, even without obstructions in the signal path. The Rician k factor generally decreases as the antenna height is lowered. The assumed 2-ray propagation model is only appropriate when the Rician k factor is much greater than zero.