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A commercial graphene nanoplatelets-based tunable attenuator is proposed. The attenuator comprises of a couple of microstrip lines connected through a gap where the commercial graphene nanoplatelets are drop casted. The transmitted signal through the microstrip line can be varied by an applied DC bias voltage that alters the graphene resistance. The DC resistance of commercially acquired graphene is higher than lab-grown graphene and so is the resulting minimum attenuation of the transmitted signal. The proposed structure is designed to reduce both the minimum graphene resistance and the transmission. The resultant dynamic range of attenuation is more than twice as compared to other series attenuators designed with lab grown graphene nanoplatelets. The operating frequency of the attenuator is from 1 to 5 GHz with maximum dynamic range of attenuation almost 10 dB.

A $5\times 9$ beamsteering reflectarray operating at $K_{a}$ -band is presented in this paper. Continuous beamsteering is achieved through the use of barium strontium titanate (BST) technology. BST is monolithically integrated into each unit cell using clean room fabrication techniques. With the application of dc bias voltage, an integrated tunable capacitor is realized. The unit cell design utilized in this reflectarray is analyzed and multiple biasing schemes are assessed. The reflectarray is designed to scan in the $E$ -plane only, and is evaluated using full-wave simulations and measurements. An appropriate feeding structure is designed and fabricated using a fused filament deposition 3-D printer, with micrometer stages used to make fine adjustments for final alignment. Overall a gain of 8.3 dBi, with a 1-dB bandwidth of 2% and continuous beamscanning from 0° to 25° at 32 GHz is demonstrated.

This Letter presents a novel, wrist-worn heart rate sensor, which is comprised of only a passive resonator and a voltage controlled oscillator (VCO). It is clearly demonstrated that valid heart rate data can be extracted off the DC bias circuit of the VCO, making this sensor one of the simplest of its kind ever reported. Experimental results are shown for successful measurements of the user's heart rate when the VCO was tuned to 2.42 GHz, with a DC bias voltage fluctuation of up to 10 mV representing the heart rate. These results are in agreement with those taken using a commercial optical sensor based heart monitor.

A novel approach to generate the flattened optical frequency comb (OFC) with tunable frequency spacing is proposed. The proposed generator consists of two cascaded polarization modulators driven by two radio frequency signals with different frequencies. By adjusting the parameters, 9, 12, and 16 comb lines can be generated with tunable frequency spacing. The scheme requires no DC bias voltage of the modulators and no optical filter, which makes our method simple and stable. A concept proof simulation is conducted to confirm the feasibility of the generation schemes of the 9-, 12-, and 16-line OFCs.

This article describes a new electrical configuration for driving piezoelectric benders. The ‘Biased Bipolar’ configuration is compatible with parallel-polled, bimorph and multimorph benders. The new configuration is similar to the standard three-wire drive method where the top electrode is biased with a DC voltage and the bottom electrode is grounded. However, the new configuration uses an alternate DC bias voltage and adjusted range for the central electrode which allows the full range of positive and negative electric fields to be utilized. Using this technique, the predicted deflection and force can be increased by a factor of 2.2 compared to the standard two wire configuration and 1.3 times for the standard three wire configuration. These predictions were verified experimentally where the measured factor of improvement in displacement and force was of 2.4 and 1.3 compared to the standard two-wire and three-wire configurations.

A novel and noninvasive method to determine the in situ etch rate (ER) of inductively coupled plasma (ICP)-etched Hg1−x Cd x Te in real time is described. Various relevant output parameters from the ICP tool were analyzed with the goal of finding correlations with the Hg1−x Cd x Te ER. Of the parameters analyzed, the most promising is the chuck direct-current (DC) bias voltage. Correlations between the chuck DC bias voltage and two different types of Hg1−x Cd x Te detector wafers are reported with a correlation coefficient of R > 0.94. Analyses of these results are presented. Estimates of the Hg1−x Cd x Te ER for all the samples based on the new method are presented and compared with the actual ER. The results show less than 3% differential between the actual and estimated ER.

We propose and demonstrate a novel reconfigurable instantaneous frequency measurement (IFM) system based on the dual-parallel Mach-Zehnder modulator (DPMZM). The IFM system can be reconfigurable with tunable measurement range and resolution by simply adjusting the dc bias voltage of the DPMZM. In principle, the measurement range could be tuned to any frequencies, which is only limited by the bandwidth of the optical transmitter and receiver employed. Alternatively, the IFM system can also work with a fixed wide measurement range and moderate resolution by generating two complementary power-fading functions.

Two kinds of Photoconductive semiconductor switch(PCSSs) with bulk structure are studied experimentally, which are fabricated from semi-insulating GaAs. The first switch has a size of 10 mm×10 mm×0.6 mm, whose electrodes are 6 mm in diameter on the opposite side of the chip. The second one has a size of 15 mm×15 mm×3 mm, whose electrodes are 8 mm in diameter on the opposite side of the chip. The withstand voltage of the first switch is tested under pulse voltages with different full-width-at-half-maximum. A maximum withstand voltage of 7.6 kV is achieved, which means the breakdown electric field is 127 kV/cm. The volt-ampere performance at DC bias voltage and dark condition of the second switch is tested as well as its triggered performance. The maximum current of the switch is more th

In this paper an electrostatically driven MEMS resonator with resonance and hysteresis characteristics is reported. The resonator begins to exhibit spring-hardening effect at ac excitation voltage of 105mV and dc bias voltage of 5V in vacuum at 50Pa. An extended hysteresis at low pressure and high excitation voltage during upsweep and downsweep of excitation frequency was observed. This characteristic facilitates the usage of this type of resonator in a range of applications such as a cascaded filter array or as a high bandwidth resonator.

Effects of pulsed voltage superimposed on dc bias voltage and meniscus height on electrohydrodynamic (EHD) spraying were investigated. Results show that greater pulsed voltages were associated with jet formation while a dripping mode was apt to appear with a lower pulsed voltage. This is because that with increasing pulsed voltages the energy gain per unit area of the liquid and the tangential electric stress at the meniscus lateral were increased more quickly than the normal electric stress at the apex of the meniscus. Additionally, the increment of meniscus height led to an unchanged tangential electric stress at the meniscus lateral, but a more quickly increased energy gain per unit area of the liquid than the normal electric stress at the apex of the meniscus. For the same pulsed voltage, spraying in Dripping I mode was produced from menisci of smaller heights due to the intensive normal electric stress. A much greater meniscus height, on the other hand, led to spraying in Dripping II mode when the pulsed voltage was insufficiently great. These various modes were determined by contributions of the tangential electric stress, the normal electric stress and the meniscus height.

This study presents two curve-fitting models of concave and convex magnetic field-effect transistor (MAGFETs) with a dc bias voltage supplied at the gate of the MAGFET. Experimental results indicate that the highest absolute sensitivity S A , supply-current-related sensitivity S RI and supply-voltage-related sensitivity S RV are 1.39 V/T, 2004.8 V/AT and 0.46 V/VT for the concave MAGFET, and S A = 0.77 V/T, S RI = 512.4 V/AT, and S RV = 0.29 V/VT for the convex MAGFET with a 3 V dc supply voltage. A magnetic device with geometric parameters, L / W = 40 μm/40 μm and d = 2 μm, is the best choice to optimize sensitivity, but a MAGFET with geometric parameters, L / W = 40 μm/40 μm and d = 4 μm, is another good choice because of its consistent geometric correction factor. The proposed arrayed and symmetrical designs can increase output voltages and eliminate unwanted errors. Broadening the drain gap not only improves the linearity of the output voltage, but also clearly makes the error correction factor consistent for both concave and convex MAGFETs. Minimizing the aspect ratio reduces the sensitivity of the concave MAGFET faster than that of the convex MAGFET. In general, both concave and convex MAGFETs are suited to fabricating magnetic devices with a wide drain gap.

A set of microwave (1–30 GHz) measuring resonators and procedure of measurements for the investigation of microwave properties of ferroelectric film planar varactors were elaborated. The fabricated resonators enabled MW losses and tunability of ferroelectric varactors under dc bias voltage to be determined. The SrTiO3 and (Ba,Sr)TiO3 film planar varactors were tested on microwaves at room temperature. A ratio of varactor capacitance at zero bias to bias conditions, K, was found as 2 for the SrTiO3 varactors and K=2.2 for the (Ba,Sr)TiO3 varactors. The microwave losses in the ferroelectric varactors were measured at frequencies of R-, X-, K-, and Ka-bands. Temperature stability of the varactor capacitance was estimated.

A linearized optical modulation scheme using a dual parallel electroabsorption modulator (EAM) and an RF 180° hybrid junction is proposed. The IMD2 generated by each EAM is suppressed by controlling the dc bias voltage of the EAM, and the IMD3 is suppressed by having a proper input optical power split ratio and an RF 180° hybrid junction. Reductions of both the IMD2 and the IMD3 at the same operation voltage were achieved, and a subsequent SFDR enhancement of 29 dB was obtained. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 373–376, 2001.

When the semiconductor substrate under the microstrip transmission lines is properly doped, a substantial phase shift of the propagating wave by an applied DC bias voltage is demonstrated. The device is inexpensive to fabricate and easy to implement, especially in monolithic structures. © 1995 John Wilet & Sons, Inc.

We investigated the mechanical coupling between the drive and detection modes of micromachined vibrating rate gyroscopes, and designed and fabricated a gyroscope with a new structure to reduce the coupling. The coupling of the oscillator was measured using a new measurement system with a two-dimensional laser displacement meter. The oscillations were found to have an elliptical motion due to the coupling. When the frequency mismatch was reduced by means of electrostatic frequency tuning with a DC bias voltage, the coupling increased. The new structure, which has independent beams for the drive and detection modes, exhibited weaker coupling; and the resolution was 0.07 deg/sec at a bandwidth of 10 Hz.

This paper reports positive switching impulse flashover characteristics of thin wire-plane gaps. Flashover tests were made under both conditions that switching impulses were added with or without ac or dc corona occurring previously. Flashover distances were up to 4 m, and ac or dc bias voltage was 400 kV crest.

The sheath effects on the current distribution along a cylindrical antenna immersed in a plasma have been investigated in two respects: 1) the measurement and its interpretation of the current distribution of the antenna in the region of f > f_{p} ( f_{p} is plasma frequency) when its dc bias voltage is varied; 2) the observation and its interpretation of the slow-wave mode along the antenna in the region of f .