Mobile propagation measurements with low antennas for segmented wideband communications at VHF

This paper reports propagation characteristics estimated from quasi-simultaneous channel measurements centered at the VHF frequencies 37.8, 57.0, and 77.5 MHz. The measurement experiments were conducted with low antenna heights (2 m) for both the base and mobile terminals and are therefore considered applicable to tactical and emergency communication scenarios. Multipath-induced time dispersion and fading are characterized respectively by root mean square (rms) delay spread and Ricean K ratio. For the area surveyed, rms delay spreads ranged from a few tens of ns to 2 μs and tended to increase with transmitter to receiver separation. Fading was predominantly Ricean rather than Rayleigh, and its severity was highly correlated with delay spread. A joint comparison of various propagation characteristics over frequency indicates a high degree of correlation between the three bands.