DSpace Collection:https://dyuthi.cusat.ac.in:443/jspui/handle/purl/8742024-03-29T13:37:10Z2024-03-29T13:37:10ZDielectric properties of ionomers at microwave frequenciesMathew, K TBiju Kumar, SAnil, LonappanJoe, JacobJacob, SamuelThommachan, XavierThomas, Kurianhttps://dyuthi.cusat.ac.in:443/jspui/handle/purl/29842012-08-01T20:30:18Z2002-10-01T00:00:00ZTitle: Dielectric properties of ionomers at microwave frequencies
Authors: Mathew, K T; Biju Kumar, S; Anil, Lonappan; Joe, Jacob; Jacob, Samuel; Thommachan, Xavier; Thomas, Kurian
Abstract: Ionic polymers (ionomers) with interesting characteristics are emerging as important commercial polymers. Ionomers have
the unique ability to behave as cross-linked materials at ambient temperatures and to melt and flow at elevated temperatures like
thermoplastics. The complex permittivity and conductivity of a class of ionomers at microwave frequencies are determined
using the cavity perturbation technique and the results are presented.2002-10-01T00:00:00ZBuried-object detection using free-space time-domain near-field measurementsBiju Kumar, SAanandan,C KMathew, K Thttps://dyuthi.cusat.ac.in:443/jspui/handle/purl/29832014-07-08T09:53:22Z2001-10-05T00:00:00ZTitle: Buried-object detection using free-space time-domain near-field measurements
Authors: Biju Kumar, S; Aanandan,C K; Mathew, K T
Abstract: The detection of buried objects using time-domain freespace
measurements was carried out in the near field. The location of a
hidden object was determined from an analysis of the reflected signal.
This method can be extended to detect any number of objects. Measurements
were carried out in the X- and Ku-bands using ordinary rectangular
pyramidal horn antennas of gain 15 dB. The same antenna was
used as the transmitter and recei er. The experimental results were
compared with simulated results by applying the two-dimensional
finite-difference time-domain(FDTD)method, and agree well with each
other. The dispersi e nature of the dielectric medium was considered for
the simulation.2001-10-05T00:00:00ZDielectric properties of certain biological materials at microwave frequencies.Biju Kumar, SMathew, K TRaveendranath, UAugustine,Phttps://dyuthi.cusat.ac.in:443/jspui/handle/purl/29822014-07-09T05:45:01Z2001-01-01T00:00:00ZTitle: Dielectric properties of certain biological materials at microwave frequencies.
Authors: Biju Kumar, S; Mathew, K T; Raveendranath, U; Augustine,P
Abstract: In the medical field, microwaves play a larger role for treatment than diagnosis. For the detection of diseases by microwave methods, it is essential to know the dielectric properties of biological materials. For the present study, a cavity perturbation technique was employed to determine the dielectric properties of these materials. Rectangular cavity resonators were used to measure the complex permittivity of human bile, bile stones, gastric juice and saliva. The measurements were carried out in the S and J bands. It is observed that normal and infected bile have different dielectric constant and loss tangent. Dielectric constant of infected bile and gastric juice varies from patient to patient. Detection and extraction of bile stone with possible method of treatment is also discussed.2001-01-01T00:00:00ZBroadband coaxial cavity resonator for complex permittivity measurements of liquidsRaveendranath, UBijukumar, SMathew, K Thttps://dyuthi.cusat.ac.in:443/jspui/handle/purl/29812012-08-01T20:30:11Z2000-12-01T00:00:00ZTitle: Broadband coaxial cavity resonator for complex permittivity measurements of liquids
Authors: Raveendranath, U; Bijukumar, S; Mathew, K T
Abstract: A novel cavity perturbation technique using coaxial cavity resonators for the measurement of complex permittivity of liquids is presented. The method employs two types of resonators (Resonator I and Resonator II). Resonator I operates in the frequency range 600 MHz-7 GHz and resonator II operates in the frequency range 4 GHz-14 GHz. The introduction of the capillary tube filled with the sample liquid into the coaxial resonator causes shifts in the resonance frequency and loaded Q-factor of the resonator. The shifts in the resonance frequency and loaded Q-factor are used to determine the real and imaginary parts of the complex permittivity of the sample liquid, respectively. Using this technique, the dielectric parameters of water and nitrobenzene are measured. The results are compared with those obtained using other standard methods. The sources of errors are analyzed.2000-12-01T00:00:00Z