D.C. Kulkarni

Perturbation of EMC Microstrip Patch Antenna for Permittivity and Permeability Measurements

The complex permittivity and permeability of barium hexaferrite in the 8-12 GHz range was determined by using perturbation of electromagnetically coupled Ag thick film patch antenna due to overlay. In this technique even minor change in the overlay material properties changes the antenna response. The power gain of the EMC patch antenna was enhanced by 50% due to barium hexaferrite overlay. Barium hexaferrite was synthesized by co precipitation method and their fritless thick films were fabricated by screen printing technique. The properties were found to depend on the synthesis conditions such as Fe/Ba molar ratio, pH of the solution.

Ku band microwave studies of fritless strontium hexaferrite thick films

Purpose – The aim of this paper is to investigate microwave Ku band absorbance, complex permittivity, and permeability of SrFe12O19 thick films by a simple and novel waveguide technique.Design/methodology/approach – The glass frit free or fritless strontium hexaferrite thick films were formulated on alumina by screen printing technique from the powder synthesized by chemical co precipitation method for pH 11 adjusted during the reaction. The 13‐18 GHz frequency band microwave absorbance of the SrFe12O19 thick films by a simple waveguide method. The complex permittivity and permeability of strontium hexaferrite thick films was measured by voltage standing wave ratio technique.Findings – SrFe12O19 thick films show high ∼80 percent absorbance in the whole 13‐18 GHz frequency band. The thickness dependant microwave properties of strontium hexaferrite thick films were observed. The real permittivity e′ lies in between eight and 35 with the variation in thickness of the thick film SrFe12O19. The real microwave ...

Dielectric and magnetic properties of substituted Li–Zn ferrite thick films clouded over a half wavelength microstrip rejection filter

Li0.35–0.5xMgxZn0.3Fe2.35–0.5xO4 nanoparticles (x = 0, 0.14, 0.28, 0.42, 0.56, and 0.70) were prepared by low-cost combustion synthesis at relatively low temperature. Thick films of Li–Mg–Zn ferrite were prepared by screen printing method and characterized by XRD and microwave characteristics at microwave frequencies (within X- and Ku-bands) by overlay technique using λ/2 rejection filter. The influence of magnesium content x on the resonance frequency, quality factor, effective dielectric constant, complex permittivity, complex permeability, microwave conductivity, and penetration depth was explored.

Influence of Mg2+substitution on the magnetic and electrical properties of Li‐Zn ferrite thick films synthesized with PVA matrix

Purpose – The purpose of this paper is to investigate the effect of Mg2+substitution on the magnetic and electrical properties of Li0.35−x Mg2x Zn0.3 Fe2.35−xO4 thick films synthesized with polyvinyl alcohol (PVA) matrix.Design/methodology/approach – The nanoferrites Li0.35−x Mg2x Zn0.3 Fe2.35−xO4 (x=0, 0.07, 0.14, 0.21, 0.28 and 0.35) were synthesized by chemical technique using aqueous solution of PVA (the matrix) and thick films were fabricated by screen printing technique. The DC magnetic hysteresis measurements, AC magnetic susceptibility and DC electrical resistivity were measured as a function of temperature.Findings – The lattice parameter of thick film Li0.35−x Mg2x Zn0.3 Fe2.35−xO4 (x=0, 0.07, 0.14, 0.21, 0.28 and 0.35) increases with the substitution of Mg2+ions for Li1+and Fe3+. The surface morphology of the thick films showed the grain size increasing with Mg2+substitution till x=0.21 and then decreasing for the higher concentrations of magnesium. The magnetic moment nB (μB) computed from the...

Microwave studies of thermally oxidized vacuum evaporated bismuth thin films on alumina

The bismuth thin films of various thicknesses (100nm-550nm) were deposited on alumina substrate by vacuum evaporation technique. These films were thermally oxidized in air at three different temperatures (125°C, 150°C, and 175°C). The films were characterized by XRD and SEM. X-ray diffraction studies shows dominant -Bi2O3 crystal structure. Surface morphology shows granular shaped particles of Bi2O3 on alumina substrate. Microwave properties were studied in the X band (8-12 GHz) using waveguide setup. The Bismuth oxide thin film showed higher microwave transmittance in the 10 to 10.8GHz range and lower reflectance. The dielectric constant and impedance at 12 GHz was measured using waveguide slotted section. The microwave dielectric constant of these Bi2O3 thin films varied from 17 to 46 at 12 GHz and was dependent on thickness and oxidation temperature

Microwave permittivity and permeability of MgxMn(0.9−x)Al0.1Zn0.8Fe1.2O4 thick films using superstrate method

Purpose – The purpose of this paper is to study thickness dependent variation in microwave properties of the MgxMn(0.9−x)Al0.1Zn0.8Fe1.2O4 (x=0.8, 0.9) thick films and enhancement of power efficiency of Ag thick film EMC patch antenna.Design/methodology/approach – X‐band microwave properties of the MgxMn(0.9−x)Al0.1Zn0.8Fe1.2O4 (x=0.8, 0.9) thick films were measured by superstrate technique using Ag thick film EMC patch antenna as the resonant element. The complex permittivity and permeability of these thick films were also measured by this technique. The microwave response of the EMC patch, complex permeability and permittivity of Mg0.8Mn0.1Al0.1Zn0.8Fe1.2O4 and Mg0.9Al0.1Zn0.8Fe1.2O4 thick films and their thickness dependency were investigated.Findings – The XRD patterns reveal the cubic spinel crystal system was obtained for both compositions. The crystallite size obtained was 134.68 nm for Mg0.8Mn0.1Al0.1Zn0.8Fe1.2O4 and 155.99 nm for Mg0.9Al0.1Zn0.8Fe1.2O4 The superstrate technique has been used succ...

Microwave characterization of barium hexaferrite by overlay technique

M type barium hexaferrite was prepared by chemical co precipitation method for the Fe/Ba molar ratios of 11:1 and 14:1. Microwave transmittance and reflectance of BaM was studied by overlay on microstrip technique. Microwave permittivity and permeability of BaM was calculated from the shift in resonant frequency of microstrip resonant circuit. The effect of molar ratio on the microwave properties of barium hexaferrite is reported.