On radio-wave propagation in forest environments
- 1 November 1967
- journal article
- Published by Institute of Electrical and Electronics Engineers (IEEE) in IEEE Transactions on Antennas and Propagation
- Vol. 15 (6), 806-817
- https://doi.org/10.1109/tap.1967.1139054
Abstract
Propagation of electromagnetic waves in forest environments at medium and high (1-100 MHz) frequencies is examined for the case where both the transmitting and receiving points are situated within the vegetation. A dissipative slab in the presence of a reflecting ionosphere is employed to describe the forest configuration. If the effect of the ground-forest interface is disregarded, the radiated field of an arbitrarily oriented, small dipole is found to consist primarily of two separate waves: a lateral wave which skims along the tree tops, and a sky wave which is produced by a single-hop reflection at the ionospheric layer. These two field constituents are compared and their domains of preponderance are calculated for a large range of the pertinent parameters; it is then found that the lateral wave plays the major role since the sky wave is restricted to a narrow frequency band and its amplitude is appreciable only at large distances. The lateral-wave field is examined in detail and is shown to yield a simple physical picture for the propagation mechanism in forests. Its features are found to be qualitatively consistent with the field behavior reported in the literature and the quantitative aspects agree well with the available experimental data. The observed variation of the field with distance, the height-gain effect, the vegetation factor, the basic path loss, and depolarization effects are separately examined and are all shown to express merely one or another of the intrinsic properties of a lateral wave. The ground-proximity effect produced by the presence of a planar-conducting ground is also estimated and shown to be of minor importance in most cases.Keywords
This publication has 12 references indexed in Scilit:
- A CONDUCTING-SLAB MODEL FOR ELECTROMAGNETIC PROPAGATION WITHIN A JUNGLE MEDIUMPublished by Defense Technical Information Center (DTIC) ,1966
- A NOTE ON THE COMPUTED RADIATION PATTERNS OF DIPOLE ANTENNAS IN DENSE VEGETATIONPublished by Defense Technical Information Center (DTIC) ,1966
- Nature and optimisation of the ground (lateral) wave excited by submerged antennasProceedings of the Institution of Electrical Engineers, 1966
- THE JUNGLE AS A COMMUNICATION NETWORK (REVISED)Published by Defense Technical Information Center (DTIC) ,1965
- On lateral waves in slab configurations and their relation to other wave typesIEEE Transactions on Antennas and Propagation, 1965
- Measurement of the attenuation of radio signals by junglesJournal of Research of the National Bureau of Standards, Section D: Radio Science, 1964
- Dipole radiation in a conducting half spaceJournal of Research of the National Bureau of Standards, Section D: Radio Propagation, 1961
- The Influence of Trees on Television Field Strengths at Ultra-High FrequenciesProceedings of the IRE, 1960
- Radio Propagation Fundamentals*Bell System Technical Journal, 1957
- Radio Propagation above 40 MC over Irregular TerrainProceedings of the IRE, 1957