Low temperature co‐fired ceramic (LTCC) reflection and delay line type microwave phase shifters utilizing completely integrated barium strontium titanate (BST) varactors are investigated. Dielectric properties of the screen printed BST paste in 1–8 GHz frequency range are presented. Sintering temperature and time were varied and their effect on the dielectric properties of the film was studied. Phase shifters were sintered at 875°C for 25 min in line with a standard LTCC sintering profile. The relative phase shift of the reflection and delay line type phase shifters were found to be 5 and 11.5° at 2.5 GHz with applied bias field strength of 8 V/μm, respectively.
In this article, an inkjet-printed inverted-F antenna suitable for a watch-type wireless communication device is presented. The antenna and covering the 2.4 WLAN band (2.4-2.484 GHz) has thickness (2 mm 3 ) and size (40 Â 25 mm 2 ). The performance of the printed antenna is experimentally studied and compared with a reference antenna made of Rogers copper laminate. The effect of inkjet-printed layer thickness on the antenna performance is presented. In addition, the impact of the user's hand proximity on the antenna performance is studied experimentally. The results showed that the total antenna efficiency increases by 13% and 27% with an increase of 1.5 lm in printed layer thickness and a user's hand to antenna distance of 12.5 mm, respectively. The shape of the radiation pattern of the antenna is distorted due to the proximity of the user's hand.
Abstract-In this work, magnetic metallic cobalt nanoparticles with an average particle size of 28 nm were processed as a dry powder with surface coating material and other organic additives to form a screen-printable ink to be cured at 110 • C. EFTEM and TGA-DSC-MS-analyses were used to measure the thickness of the polymer, its coverage on cobalt nanoparticles and the inorganic solid content of the ink. The resolution of the printed patterns and the print quality were evaluated by surface profiler, FESEM and optical microscopy. The relative permeability of the thick film patterns with good printability was measured with a shorted microstrip structure over the frequency range of 0.2 to 4 GHz and complex permeability values were calculated from measured scattering parameter data. The ink attained real part of complex permeability values of up to 5.13 at 200 MHz with 70 wt.% of magnetic filler. The developed ink can be utilized in various printed electronics applications such as antenna substrates and magnetic sensors.
Previous ink characterization results published in the paper are corrected by new characterization measurements from Co inks based on same cobalt nanoparticles bound together with poly(methyl methacrylate). New measurements results are reported as vol% whereas previous results were reported as wt.%. Correlations are 30 vol% = ∼80 wt.%, 40 vol% = ∼86 wt.% and 50 vol% = ∼90 wt.%. According to the LandauLifchitz Gilbert theory, the ferromagenetic resonance of a magnetic film can be defined aswhere H S is the saturation magnetic filed, M A is the anisotropic constant, γ is the gyromagnetic ratio.Further, from constituent relations,
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