In moving from a measurement of Glioma apparent permittivity in the time domain towards a measurement of true permittivity and loss in the frequency domain, of critical importance is the removal of the response of the TDR or coaxial probe from the measurement. The following section details the electrodynamics to form a frequency response characterization for later removal of confounding affects to obtain a measurement of the true permittivity of the soil.Formulation of frequency response of through-transmission coaxial probe. As the TDR probe is closely aligned to the coaxial cable, the analysis starts with the formulation for a coaxial cable by which to find the frequency response of the structure.
We note that for propagation of a free-space Inhibitors,Modulators,Libraries plane wave, in Inhibitors,Modulators,Libraries a source-less region that is directed only in the z direction, the form of the wave propagation can be shown to have the form of Equation 1, with the propagation coefficient �� as shown Inhibitors,Modulators,Libraries in Equation (2) [19], which can be derived from the phasor form of Maxwell��s electromagnetic equations (1):?��H=j?D+J?��E=?j?��H?��H=j?D+J=j??E+��E=E(j??+��)=E(j?(?��?j?��)+��)(1)where: = �� ? j��[complex permittivity (F/m)]�� = r��0[real component of complex permittivity]�� = r��0[imaginary component of complex permittivity]D = E[displacement flux]J = ��E[conduction current density]B = ��H[magnetic flux density]?��H=E(j?(?��?j?��)+��)=(j??��+??��+��)E=j?(?��?j?��?j��?)E=j?(?��?j(?��+��?))E?��H=j?(?��?j(?��+��?))E=j?(?��?j??��?+��?)E=j?(?��?j??��+��?)E?��H=j?(?��?j??��+��?)E=j??��(1?j??��+��?��?)E=j??��(1?j tan ��)Ewhere:tan �� ???��+��?Taking curl of both sides?��(?��E)=?��(?j? ��H)=?j? ��(?��H)=?j? ��(j??��(1?j??��+��?��?))E?��(?��E)=(��?2?��(1?j??��+��?��?))E?��?��E=?(??E)??2ENoting in a source free region ? E = 0?��?��E=??2E=��?2?��(1?j??��+��?��?)E=(��?2?��(1?j tan ��))E?2E+��?2?��(1?j??��+��?��?)E=0In defining the wave-number k2, solution to the Helmholz wave equation, as the coefficient to ��E��:k2=��?2?��(1?j??��+��?��?)which then provides the propagation coefficient �� as:��=jk=��+j��=j��?2?��(1?j(??��+��??��))=j?��?��(1?j(??��+��??��))=j?��?��(1?j tan ��)which is used in the solution to the Helmholz wave equation, propagating in the plus z direction with magnitude E+, as:Ex (z)=E+e?jkz=E+e?��z=E+e?(��+j��)z=E+e?��ze?j��zwhich can also be equivalently represented in the time domain as:Ex (t,z)=E+e?��zcos(? t?��z)from which we can see the phase of t
A sensor is defined from an engineering point of view as a device that converts a physical, chemical, or biological parameter Cilengitide into an electrical signal [1].
Common examples include sensors for measuring temperature (i.e., a thermometer), wind speed (an anemometer) conductivity, or solar radiation. While a sensor is the most basic unit, a sensor system is an aggregation of sensors, attached to a single choose size platform [2]. Examples are a weather station with attached sensors, or a combination of heart frequency and blood pressure sensors carried by a human or animal. A sensor or a sensor system may be abstracted as a sensor resource.