Millimeter-wave propagation in vegetation: experiments and theory

Abstract

Microwavelmillimeter-wave propagation in woods and forests was investigated at 9.6, 28.8, and 57.6 GHz. In order to perform the measurements under well defined, reproducible conditions, a regularly planted, well groomed stand of trees of about the same growth (pecan orchard near Wichita Fails, TX) was chosen as the test site. The experiments were repeated, over the same transmission paths, under both summer and winter conditions, i.e., with trees in leaf and without leaves. Of particular interest were the range dependence, beam broadening, and depolarization of millimeter-wave beams in vegetation and the frequency dependence of these effects. The experiments have shown, in particular, that the range dependence is characterized by a high attenuation rate at short vegetation depths and a reduced attenuation rate at large depth. For trees fully in leaf, the transition between the two regimes can be rather abrupt and the change in attenuation rate substantial. Just after the transition significant beam broadening (and depolarization) occurs. A theory of millimeter-wave propagation in vegetation was derived using transport theory. Theoretical and experimental results are in good qualitative agreement; both show the same trends. The theory explains these trends in terms of the interplay between the coherent (direct path) field component and the incoherent (multiscattered) field component. Achieving good quantitative agreement will require further refinement of the theory.

Indoor Corridor Wideband Radio Propagation Measurements and Channel Models for 5G Millimeter Wave Wireless Communications at 19 GHz, 28 GHz, and 38 GHz Bands

“…The angular spread parameters for 28 GHz and 38 GHz are estimated at 3 m and 6 m based on (9) and (10). The angular spread parameters are listed in Table 2.…”

“…6 GHz bands in downtown Denver, where the results showed significant signal attenuation due 2 Wireless Communications and Mobile Computing to obstruction by large buildings [9]. Propagation through a canopy of orchard trees was measured using continuous wave (CW) signals at 9.6, 28.8, and 57.6 GHz [10].…”

“…Several channel measurements have been conducted at some mmWave bands such as 6,10,11,15,18,19,26,28,32, and 38 GHz bands. In [11], the propagation characteristics of mmWaves were investigated in an indoor corridor environment for the line of sight (LOS) scenario at 6.5, 10.5, 15, 19, 28, and 38 GHz bands.…”

Channel Models and Beamforming at Millimeter-Wave Frequency Bands

“…Deployment of mm-wave radios for broadband data transfer was considered in the late 80's for outdoor scenarios. The deployment mainly concerns fixed point-topoint links, where the radio wave propagation in urban street canyons and the attenuation due to penetration through tree canopies were reported already as influential phenomena of such links [2], [3]. Later in the 90's the deployment scenario was extended to indoor scenarios where human blockage and penetration loss through walls are the major interests of investigation to determine the coverage and the link budget.…”

Investigations of Foliage Effect on Modern Wireless Communication Systems: A Review

“…From the open literature, the application of the RET theory to model the radio-wave propagation in foliage medium was first reported in [27] and later discussed by Schwering et al [28] and Al-Nuaimi et al [29]. However, it is noted that the RET approach is generally applied to a homogeneous medium.…”