11,562 research outputs found
Design of a New Step-like Frame FBAR for Suppression of Spurious Resonances
Film bulk acoustic wave resonators (FBARs) are of great interest for wireless applications due to its inherent advantages at microwave frequencies. However, the presence of spurious modes near the main resonance degrades the performance of resonators and requires development of new methods to suppress such unwanted modes. Different techniques are used to suppress these spurious modes. In this paper, we present design of a new step-like frame structure film bulk acoustic wave resonator operating near 1.5 GHz. The simulated results are compared with simple frame-like structure. The spurious resonances are eliminated effectively and smooth pass band is obtained with effective coupling coefficient of 5.68% and quality factor of 1800. The equivalent electrical mBVD model of the FBAR based on impedance response is also presented. These highly smooth phase response and passband skirt steepness resonators are most demanding for the design of low cost, small size and high performance filters, duplexers and oscillators for wireless systems
A polarization insensitive ultrathin compact triple band metamaterial absorber
In this paper, design, characterization and measurements of an ultrathin compact polarization insensitive triple band metamaterial absorber for wide incident angle have been presented. The unit cell design consists of a Jerusalem cross shaped resonator inside a square loop resonator. The proposed absorber exhibits triple band absorption at 4.4, 6.48 and 15.44 GHz with 96.6% and 97.64% and 85.81% absorptivity, respectively, for wide incident angles of electromagnetic wave. The absorption frequencies can be effectively adjusted for C, X and Ku frequency bands by optimizing the dimensions of the absorber design. The proposed absorber is ultrathin (0.014 λ0) in thickness and compact (0.12 λ0) in size at the lowest frequency of absorption. The proposed absorber exhibits TE and TM polarization stability and provides high absorption up to the incident angle of 60°. A prototype of the proposed absorber structure has been fabricated and experimentally tested for normal and oblique incidences for TE and TM polarization. The measured responses have been observed in agreement with the simulated ones
Possible ~ 1 hour quasi-periodic oscillation in narrow-line Seyfert 1 galaxy MCG--06--30--15
We found a possible ~ 1 hour quasi-periodic oscillation (QPO) in a ~ 55 ks
X-ray observation of the narrow-line Seyfert 1 galaxy MCG--06--30--15 made with
the XMM-Newton EPIC/pn detector in the energy range 0.3 -- 10 keV. We identify
a total modulation of ~ 16% in the light curve and find a 3670~s
quasi-period using Lomb-Scargle periodogram (LSP) and weighted wavelet
Z-transform (WWZ) techniques. Our analyses of eight light curves of
MCG--06--30--15, indicated the possible presence of an oscillation during one
of them. The LSP indicates a statistically significant ( 3) QPO
detection. A WWZ analysis shows that the signal at this possible roughly 3670s
period is present, and rather persistent, throughout the observation; however,
a signal around 8735s is more persistent. We briefly discuss models that can
produce X-ray QPOs with such periods in narrow line Seyfert 1 galaxies, as both
other claimed QPO detections in this class of AGN had very similar periods.Comment: 5 pages, 4 figures, Published in A&A Letter
Non-Fermi-liquid behavior at anti-ferromagnetic quantum critical point in heavy fermion system Ce(CuCo)Ge
Polycrystalline samples of Ce(CuCo)Ge were investigated
by means of electrical resistivity (), magnetic susceptibility
(), specific heat () and thermo electric power ()
measurements. The long-range antiferromagnetic (AFM) order, which set in at
= 4.1 K in CeCuGe, is suppressed by non-iso-electronic cobalt
(Co) doping at a critical value of the concentration = 0.6, accompanied
by non-Fermi liquid (NFL) behavior inferred from the power law dependence of
heat capacity and susceptibility i.e. ()/ and ()
down to 0.4 K, along with a clear deviation from
behavior of the electrical resistivity. However, we have not seen any
superconducting phase in the quantum critical regime down to 0.4 K.Comment: 8 pages, 11 figure
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