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Abstract: A broadband and circularly polarized 1×4 linear antenna array composed of CPW-fed slot elements for millimeter wave application is discussed. Through a special short-circuiting stub perturbation method, the circular ring slot element achieves circular polarization and a broad bandwidth. Through a parallel feeding network, the array achieves a broad impedance bandwidth of 19% with VSWR⩽2 and CP bandwidth of 18.4% with AR⩽3dB and has a peak gain of about 6.8dB. [Copyright &y& Elsevier]

Abstract: A fast switching electromagnetic microactuator with two stable positions is presented. The actuator consists of a cantilever beam with two free ends, a torsional beam with two fixed ends, planar coils and permanent magnets. The cantilever beam has two stable positions due to the use of the permanent magnets. With electromagnetic actuation arising from the planar coils, the cantilever beam will switch from one stable position to the other. The behaviour of the microactuator is studied using a coupled electromagnetic-mechanical FEM-simulation with ANSYS software. The working mechanism for the bistability of the actuator is analysed. The device with a size of 2.0mm×2.2mm is fabricated by UV-LIGA technology using sacrificial layer. The results of test show that a current pulse with an amplitude of 50mA is needed for actuator’s switching between two stable states, and the switching time is approximately 20μs. The displacement of the end of cantilever is about 17μm. [Copyright &y& Elsevier]

Abstract: In this paper, a new micromachined interdigital coplanar waveguide (CPW) structure has been developed and its characteristics have been studied as a function of transmission line parameters. In interdigital CPW, the ground conductor is thickened by micromachining techniques which is helpful for reducing the interference between the adjacent center conductors while microwave transmits along it. Within the frequency range from 5 to 20GHz, the return loss of this structure has two minimal values whose positions change with the structural parameters. The relative bandwidths reached 23.5% and 9.97% at 8.3 and 16.55GHz while the insertion losses are about 0.33 and 0.5dB/cm, respectively. The interdigital CPW is useful for designing bandpass filter and phase shifter and minimizing the whole size of microelectromechanical system (MEMS) devices. [Copyright &y& Elsevier]

Abstract: With the wafer-bending method and spectrophotometry, the internal stress in electroplated Ni–Fe alloy for MEMS has been investigated as a function of bath concentration. This investigation demonstrated that low concentration plating solution is useful for the decrease of the residual stress in the electrodeposits, and the stress could further decrease with an increase of saccharin additive content. And the change of stress from tensile to compressive was not observed with the increase of the additive content in plating path. The low stress permalloy (Ni81Fe19) was reached in our experimental conditions. A bistable electromagnetic RF MEMS switch with deformation-free bilayer cantilever beam was fabricated successfully by electroplated permalloy. [Copyright &y& Elsevier]

The Young''s modulus and residual stresses of electroplated copper film microbridges were measured. Special ceramic shaft structure was designed to solve the problem of getting the load-deflection curves of the microbridges from a nanoindentation system equipped with a normal Berkovich probe. Theoretical analysis of the load-deflection curves of the microbridges is proposed to evaluate the Young''s modulus and residual stress of the copper films simultaneously. The calculated results based on the experimental measurements showed that the average Young''s modulus and residual stress of the electroplated copper films are 115.2 GPa and 19.3 MPa, respectively, while the Young''s modulus measured by the nanoindenter for the same copper film with silicon substrate is 110±1.67 GPa. [Copyright &y& Elsevier]