An empirical result for the height gain in forest medium

Tewari, R. K.; Swarup, S.; Roy, Moumita

doi:10.1109/tap.1984.1143232

Cited by 16 publications

(13 citation statements)

References 4 publications

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“…Similar findings are reported in [1]. The height gain found in [6], based on the idealised flat Earth propagation model, is given as: In the current scenario with relative high carrier frequency and short distances the shape of the trees with bare trunks below a branchy region might be more important than ground reflections and the 20 . log10(h r .…”

Section: B Height Gainsupporting

confidence: 71%

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Deployable WiMAX in a forest area; channel measurements and modelling

Voldhaug

Bråten

Sander

2010

2010 - Milcom 2010 Military Communications Conference

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The performance of vehicle mounted WiMAX equipment has been tested in a forest environment. Path attenuation was measured at 2.3 GHz with a bandwidth of 5 MHz during the summer season. With a base station sector antenna with adjustable mast height and an omni-directional vehicle antenna at 2 m height, the received signal strength was recorded in a number of stationary positions. The excess attenuation caused by the vegetation is found to be reasonably well modelled by the current ITU-R prediction method for one terminal in woodland. The maximum attenuation was extracted from the measurements to adjust the ITU-R model to the local environment and the four base station antenna heights employed. Only moderate variation in vegetation attenuation was observed between the base station antenna heights of 3.5, 5.5, and 10.5 m, while at 14 m height the attenuation was about 5 dB lower. Shadow attenuation in dB follows a Gaussian distribution reasonably well. The highest standard deviation was observed for transmit antenna height of 14 m, where it reached 8 dB. Thus, moderate improvement in signal strength was achieved by elevating the transmit antenna, with somewhat lower average path loss at the highest antenna position. When utilising 2 nd order base station antenna diversity the lowest base station antenna height benefitted most from diversity. The downlink diversity gain observed is significantly less than in the uplink. The measurements indicate that a range of about 700 m can be achieved for this setup in this environment.

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Section: B Height Gainsupporting

confidence: 71%

“…Measured and modelled downlink excess attenuation, adjusted maximum attenuation Height gain relative to transmit antenna height of 5.5 m with a receive antenna height of 2 mincrease in relative gain for heights below the minimum of 5 -6 m is not captured by the linear regression models(6).…”

mentioning

confidence: 99%

Deployable WiMAX in a forest area; channel measurements and modelling

Voldhaug

Bråten

Sander

2010

2010 - Milcom 2010 Military Communications Conference

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“…For the plain terrain effect, analytical [18,19] and experimental [7,37,44] studies show that, the ground reflection from a plain forested terrain plays a significant role on the radio wave propagation at VHF and UHF bands. The experimental results in [7,37,44] show that the ground reflection can result in a similar antenna height-gain effect as in [37] and [46] (proportional to h 2 T h 2 R ). For the hilled forested terrain effect, Meeks [49] started the investigation of the diffraction due to a forested hill at VHF.…”

Section: Terrain Effectmentioning

confidence: 69%

“…After the introduction of antenna height-gain on the propagation loss analytically [9] and experimentally [37,45], Tewari et al [46] performed an in-depth empirical modeling of antenna height-gain on the path loss in the forest. Based on the results of measurement conducted in various tropical rainforest, with foliage depths of up to 4 km in India, the empirical model is derived.…”

Section: Antenna Height-gain Effectmentioning

confidence: 99%

Study of Propagation Loss Prediction in Forest Environment

Meng¹,

Lee²,

Ng³

2009

PIER B

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Abstract-A comprehensive review of radio wave attenuation in forest environments is presented in this paper. The classic analytical methods of propagation loss modeling and prediction are described first. This provides information on the physical processes that the radio waves undergo while propagating through a forest. The focus of this paper is on the review and summary of the experimental work done in this area and the development of empirical propagation loss prediction models. The propagation loss variation due to external factors such as antenna height-gain, depolarization, humidity effect etc. are examined and discussed individually. In view of current research work done in this area, some possible future work is proposed to improve the performance of radio links in forest environment.

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“…They have been carried out under different operational contexts and in different physical situations concurrently with theoretical studies [5]- [20]. Ground reflection [21], depolarization [24], antenna height gain [25], seasonal variation [27] etc. on the propagating radio wave in the forested environment have been discussed respectively.…”

Section: Chapter 1 Introductionmentioning

confidence: 99%

VHF and UHF wireless channel measurement and modeling for foliage environment

Meng¹

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In this thesis, a detailed study on channel characterization and modeling of the forested environment for military applications such as surveillance and battlefield communication networks is undertaken. The scenarios of military applications such as communication systems mounted on vehicles or carried by soldiers, require knowledge of near-ground radio wave propagation in forests at VHF and UHF bands. In this research study, a series of experimental work was carried out in different types of foliage plantations, forested depth, and weather conditions, to examine the effects of radio wave propagation through forested paths. The path loss in the forests, for near-ground communication systems, can be empirically modeled using well-known through-vegetation loss models with the ground reflection taken into consideration. Depending on the type of forests or plantations, the through-vegetation loss models such as Weissberger, ITU-R, COST235 and FITU-R models can be used to model the forested propagation loss. However, our experimental study shows that, the prediction accuracy using these through-vegetation loss models decreases gradually as the forested depth increases.

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An empirical result for the height gain in forest medium

Cited by 16 publications

References 4 publications

Deployable WiMAX in a forest area; channel measurements and modelling

Deployable WiMAX in a forest area; channel measurements and modelling

Study of Propagation Loss Prediction in Forest Environment

VHF and UHF wireless channel measurement and modeling for foliage environment

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