Cavity perturbation technique is widely used in the measurements of complex dielectric permittivity of materials due to its accuracy and ease of configuration. This paper presents the theoretical formulas for the evaluation of complex permittivity of materials using cavity perturbation technique with substrate integrated cavity resonators. With the proposed formulas, the use of various planar cavities is possible by taking into account the dielectric characteristics of the substrate in which the cavity is implemented. Simulations and measurements are performed on various dielectric samples to validate the proposed theory. The maximum deviation in the measured dielectric permittivity values is below 6% compared to the literature values. The implemented substrate integrated cavity is then analyzed in terms of sensitivity, showing a good performance.
Magnetoelectric interactions as a function of applied electric field have been studied in ferrite-ferroelectric heterostructures at microwave frequencies. The measurements are performed on 1.5–2.0 μm thick nickel ferrite (NiFe2O4) films grown heteroepitaxially on lead zinc niobate-lead titanate and lead magnesium niobate-lead titanate substrates using direct liquid injection chemical vapor deposition. Large shifts in the ferromagnetic resonance profile are observed in these heterostructures due to strong magnetoelectric coupling resulting from electrostatic field induced changes in the magnetic anisotropy field. Theoretical estimates of field shifts are in good agreement with the experimental data.
Abstract-A novel compact Epsilon Near Zero (ENZ) tunneling circuit with microstrip coupling for high integrability applications is presented. Full design procedure, simulation and experimental results are shown, and a methodology to extract the effective permittivity and propagation constants in the tunnel is described. Detailed analysis of the dependence on external quality factor and tunnel to feed height ratio is investigated. Simulation and measurement results of the ENZ tunnel structure are in good agreement.
Composite nanofibers from poly(methylmethacrylate)- (PMMA-) conducting polyaniline [PANI(HCl)] were prepared by using the electrospinning technique. The morphology and structural details of the fibers were characterized by SEM and the ac conductivity of the composite fibers found was measured to be ∼ 2.17×10−4 S/cm which is very good enhancement compared to that of pure PMMA and conductivity of PANI-PMMA thin films as well. The conductivity is found to increase with increase in the polyaniline content in the composite. Microwave Hall mobility measurements on electrospun nanofibers showed 17 cm2/V s for the lower loadings. With further increase in the polyaniline content in the composite, the mobility value decreases which is attributed to the increase in carrier-carrier scatterings.
Abstract-A new design of microwave band pass filter design is presented using metamaterial-inspired Epsilon Near Zero (ENZ) and Mu Near Zero (MNZ) behaviors. These filters are based on waveguide technology. The proposed structure allows us to reduce the number of tunnels normally used for passband filter design by reducing its size. It is also incorporated the half mode concept to the tunnels leading a greater miniaturization. Two Chebyshev filters with two and fourpoles were designed, fabricated and measured showing good agreement between simulated and experimental results.
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