Improved Permittivity Calibration Method for Wideband In Situ Permittivity Probe
This letter discusses about an improved permittivity probe calibration method for calculating the complex permittivity of soils from reflection data over a very wide bandwidth. The accuracy of this method is demonstrated using reflection data collected from a unique wideband (10-1000 MHz) permittivity probe specifically designed for quick in situ permittivity measurements of soils at different depths. The improved calibration method is based on the traditional capacitance model, which suffers from errors caused by the assumption that the capacitance is independent of the frequency and the permittivity of the ambient medium under test. The improved capacitance model is introduced here to account for the frequency- and permittivity-dependent effects. Thus, it produces more accurate permittivity estimation over a much wider frequency and permittivity ranges. This letter will discuss about the accuracy of this improved permittivity probe calibration method and a wideband in situ soil probe design.
Material Characterization of Arbitrarily Shaped Dielectrics Based on Reflected Pulse Characteristics
The relative permittivity of materials is extracted using time domain radar pulse reflection measurements. The pulse reflected from an arbitrarily shaped dielectric object is compared with that reflected from its metallic equivalent to determine the object's dielectric constant. The proposed method achieves accuracies of over 85% for permittivity and within 2 mm for material thickness estimations. Using the proposed technique, the complex relative permittivity for various objects is extracted over a frequency range from 3 to 10 GHz. This method has been applied to determine the permittivity of a ridge of sand and to dielectric imaging.
MAGNETIC SUSCEPTIBILITY OF THE SOIL AND ITS SIGNIFICANCE IN SOIL SCIENCE – A REVIEW
Summary 
The magnetic susceptibility of soil minerals is discussed, and in particular that of the ferrimagnetic minerals, maghemite, magnetite, and the titanomagnetites since one or more of these usually dominates soil magnetic properties. The magnetic susceptibility of soil depends on the shape, size, and concentration of these minerals as well as on the method of measurement. Measurements performed in a weak alternating magnetic field are the most reliable. 
 
The identification, formation, and occurrence of soil maghemite is considered in detail since it is usually of pedogenic origin and occurs in (magnetically) detectable amounts in most soils. Moderate concentrations (>1 per cent) of magnetite or titanomagnetite in soils may be accurately measured if some of the material is first magnetically separated and its susceptibility determined. An example is given of the use of susceptibility measurements. Pedogenic maghemite may be determined in soils developed from parent materials of low susceptibility. A very rough value of 8.8 × 10−4 m3 kg−1 is suggested for the mass susceptibility of such maghemite (excluding magnetic concretions). 
 
Although susceptibility has been suggested as an indicator of soil forming processes, this is only possible within an area containing fairly uniform parent material.