L-Band Reflectivity of a Wire Grid Above a Dielectric Surface

Völksch, Ingo; Schwank, Mike; Mätzler, Christian

doi:10.1109/lgrs.2010.2042786

Cited by 5 publications

(3 citation statements)

References 11 publications

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“…The L-band radiometer ELBARA [16] was constructed at the Institute of Applied Physics, University of Bern (Switzerland), in 2001 and has been successfully deployed in numerous experiments since then [19]- [25]. It is equipped with a dual-mode Picket-horn antenna [18] (aperture diameter d = 1.4 m, length l = 2.7 m) with a gain of 23.5 dB and a −3 dB full beamwidth of 12…”

Section: B Instrumentationmentioning

confidence: 99%

L-Band Reflectivity of a Furrowed Soil Surface

Völksch

Schwank

Mätzler

2011

IEEE Trans. Geosci. Remote Sensing

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Abstract-In a combined experimental and model study, we investigated the thermal L-band signatures of a sandy soil with periodic topography (furrows) with dimensions close to the observation wavelength of 21 cm. Measurements were carried out with a radiometer mounted on a tower and aimed at a soil box with an artificially prepared furrowed soil surface. Corresponding reflectivities were derived from brightness temperature measurements performed under dry and moist conditions, with the furrow direction either along or perpendicular to the plane of incidence. Results showed that the furrows had a pronounced effect on the reflectivity, depending on the polarization of the observed radiance, the direction of the furrows, and the soil moisture. A physical reflectivity model for dielectric periodic surfaces was used to explain the soil reflectivities measured for the different furrow directions and soil-water contents. Using this model improved the agreement between the measured and modeled reflectivities considerably compared to the Fresnel reflectivities. The observed dependence of soil reflectivity on furrow orientation and soil moisture could be reproduced by the reflectivity model. The quantitative agreement with the observed reflectivities was further improved by using a simple empirical approach to consider the small-scale heterogeneity of the top soil layer.Index Terms-Electromagnetic scattering by periodic structures, electromagnetic scattering by rough surfaces, microwave radiometry, permittivity.

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Section: B Instrumentationmentioning

confidence: 99%

L-Band Reflectivity of a Furrowed Soil Surface

Völksch

Schwank

Mätzler

2011

IEEE Trans. Geosci. Remote Sensing

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“…The gaps or openings do not need to be large, typically the size of a few wavelengths in order for the radiation to propagate through relatively unperturbed. This is known since long and was illustrated recently in the case of Lband with a wire grid above a dielectric surface, [26]. We therefore introduce in the model, describing the interaction between microwaves and forest, a measure of the fractional area of ground reached by the microwave radiation directly in line of sight from the satellites, and the backscatter from different layers of the dense (no gaps down to ground) forest fraction plus the attenuated part from the ground.…”

Section: A the Modelmentioning

confidence: 99%

Boreal Forest Properties From TanDEM-X Data Using Interferometric Water Cloud Model and Implications for a Bistatic C-Band Mission

Askne

Ulander

2021

IEEE J. Sel. Top. Appl. Earth Observations Remote Sensing

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Data from TanDEM-X in single-pass and bistatic interferometric mode together with the interferometric water cloud model (IWCM) can provide estimates of forest height and stem volume (or the related above-ground biomass) of boreal forests with high accuracy. We summarize results from two boreal test sites using two approaches, i.e. 1) based on model calibration using reference in-situ stands, and 2) based on minimization of a cost function. Both approaches are based on inversion of IWCM, which models the complex coherence and backscattering coefficient of a homogeneous forest layer which includes gaps where free-space wave propagation is assumed. A digital terrain model (DTM) of the ground is also needed. IWCM is used to estimate forest height or stem volume since the two variables are assumed to be related through an allometric equation. A relationship between the fractional area of gaps, the area-fill, and stem volume is also required to enable model inversion. The accuracy of the stem volume estimate in the two sites varies between 16% and 21% for height of ambiguity <100 m. The results clearly show the importance of using summer-time acquisitions. Based on the TanDEM-X results at X-band, C-band data from the ERS-1/ERS-2 tandem mission are revisited to investigate the potential of a future bistatic C-band interferometric mission. Out of nine ERS-1/ERS-2 pairs, only one pair was found to be acquired at summer temperatures, without precipitation and with high coherence. A simulated bistatic phase height is shown to give approximately the same sensitivity to stem volume as TanDEM-X.

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“…In [23], King and Smith considered an approximating solution of this equation, when dipoles are boreholed in dielectrics. The validation of King's expression through experimental measurements was done by Sato and Thierbach [24] and by Völksch, Schwank & Mätzler [25]. Using King's approach, for a dipole of length 80cm with a feed at point z=0 with V 0 =1V, the current distribution is equivalent to the current distribution on a transmission line of length l/2 [26].…”

Section: Jinst 8 P03010mentioning

confidence: 99%

Considerations on an underground neutrino radio detector in salt

Badescu¹

2013

J. Inst.

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This article presents the possibility of in-salt radio detection of high energy neutrinos, and shows the implications that a heterogeneous propagating medium has on both antenna behaviour, and on constructing the detector. Based on several factors (propagation effects signal to noise ratio, minimum necessary number of triggers, etc.) it was found that observations are limited at a 10 22 eV energy threshold. This higher limit allows both neutrino characteristics, and internal structure of the dome to be simultaneously determined. A total number of 40 to 200 events per year is expected when typical sedimentary layers of about 5cm are considered for the internal salt dome structure.

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L-Band Reflectivity of a Wire Grid Above a Dielectric Surface

Cited by 5 publications

References 11 publications

L-Band Reflectivity of a Furrowed Soil Surface

L-Band Reflectivity of a Furrowed Soil Surface

Boreal Forest Properties From TanDEM-X Data Using Interferometric Water Cloud Model and Implications for a Bistatic C-Band Mission

Considerations on an underground neutrino radio detector in salt

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