Phase Shifter

A novel low-cost packaging approach is presented in this paper, which is appropriate for high-frequency electronic circuits in discrete, as well as integrated, configurations. This approach is based on silicon micromachining and can effectively provide on-wafer and discrete packaging for high-quality highprecision miniature components. The required fabrication techniques are compatible with standard integrated-circuit processing and, for this reason, are low in fabrication costs. As an example, this paper presents the development of a Ka-band package that can shield and electromagnetically isolate monolithic-microwave integrated-circuit components, such as a phase shifter. The performance of this package is compared to that of a ceramic one and demonstrates excellent electrical response in addition to high design versatility.

The low frequency rf linacs and bunch compressors in the NLC are heavily loaded by beam currents up to 0.9 A. Beam loading generates bunch-to-bunch energy deviations, which need to be compensated to operate with long bunch trains in the linear collider. There are two basic compensation techniques, namely T and F schemes. The F scheme is operationally straightforward but requires additional rf systems which are powered at slightly different frequencies. In contrast, the T scheme does not require any additional rf and is thus expected to be less expensive. Here, the loading compensation is realized by early injection combined with rf phase and amplitude modulation. The phase/amplitude modulation is performed with fast phase shifters at low rf power before amplification by the klystrons. With combined phase and amplitude modulation, the T scheme can be applied to both the accelerator and compressor linacs. In this paper, we present simulations of the T compensation scheme for the NLC low rf accelerator and compressor linacs. We discuss different rf configurations using the T scheme as well as some issues related to phase/amplitude modulations in such layouts.

A fully integrated 24GHz 4-channel phased-array transceiver in 0.13μm CMOS is reported. The architecture is based on a variable-phase ring oscillator in a PLL that modulates the baseband for each antenna in the TX mode and downconverts the received signal from all antennas in the RX mode without using RF mixers, signal-path phase shifters, or any power combining network. The 2.3 × 2.1 mm2 chip achieves an array transmit EIRP > 23.8dBm, RX gain > 42dB, and can scan the beam continuously

To guarantee the secure and reliable operations of power systems through the rapid damping of low-frequency electromechanical oscillations (LFEOs) is the ultimate objective of this study. This paper presents a coordination of a flexible AC transmission system (FACTS) device and power system stabilizer (PSS) to meet this objective, and deals with the design of a damping controller based on a thyristorcontrolled phase shifter (TCPS) and a PSS. The proposed design is incorporated in the framework of a single-machine infinite-bus (SMIB) power system. The effectiveness of the proposed design in damping power system oscillations is explored through eigenvalue analysis, time-domain simulations and damping torque contribution. A comparative study on different control schemes, such as with an SMIB including a PSS and an SMIB including a TCPS-based damping controller is also carried out. The obtained results prove the superior performance of the proposed design in improving the stability of the given power system. All the digital simulations are performed using MATLAB/ SIMULINK.

The design, analysis and implementation of a high frequency 1-3GHz tunable pure NMOS Quadrature Up-Conversion mixer topology are presented. The mixer is implemented in a deep submicron 0.25μm CMOS process technology. Utilizing an off-chip tunable inductor had achieved tunable range of frequency. Various passive components had been incorporated in the circuitry to increase the linearity of the topology. The mixer, which is a configuration of a balanced modulator, is composed from a Parallel Structure Low Voltage Multiplier topology, High Gain Phase Shifting network and a Differential Cascode amplification stage at the output. Various topology of four quadrant multiplier, biased in different region of operation had been simulated and analyzed. The utilized topology requires fewer amounts of stacked transistors, thus reducing the voltage headroom requirement of the circuitry. The proposed high gain phase shifter relaxes the requirement of cascading several stages of limiting amplifier at the output. Operating from a power supply of 2.0V, it consumes 150mW of power, with an OIP3 of 0dBm and 1dB compression level of 4.6dB.

This paper presents the design of a monolithic phased array antenna with DMTL phase shifters on quartz substrate operating at 35 GHz. The design integrates DMTL phase shifters, rectangular slot antennas with the feed network comprising CPW lines, CPW T-junction and corners. On the four branches of the antenna, there are 5-bit phase shifters using 31 MEMS bridges, covering 360° with a resolution of 11.25°.

HURUF BESAR) mengaku membenarkan tesis (PSM/Sarjana/Doktor Falsafah)* ini disimpan di Perpustakaan Universiti Teknologi Malaysia dengan syarat-syarat kegunaannya seperti berikut: To my parents and family, for their guidance, support, love and enthusiasm. Without these things this thesis could not have been possible. iv ACKNOWLEDGEMENT Praise is to Allah who has given me the strength, physically and mentally in order for me to complete this thesis. I extend my sincere gratitude and appreciation to many people who made this master's project possible. Special thanks to my supervisor Dr. Mohamad Kamal Abd Rahim for their invaluable guidance, suggestions and full support in all aspects during the whole process of the project. The thank goes also to my lecturer Assoc. Prof. Dr Jafri Din that was indirectly involved in this project. Many thanks go to Mr. Mohamad Zoinol Abidin and Mr. Azhari Asrokin from the Wireless Communication Centre for their suggestions and help in fabricating the final device. Finally, I would also like to thanks my entire friend and whoever involved for their valuable help during my project and for providing me with useful information. v ABSTRACT This thesis describes the design of a compact miniature and low cost microstrip dipole antenna integrated with 90 0 hybrid coupler, oscillator and diodes for direct conversion, or zero IF receiver. The frequency chosen is at 2.4 GHz, which is of particular interest for RFID application. In this receiver design, Agilent's ADS software using momentum simulation and circuit simulation is employed to analyze the entire structure. In the fabrication process, the proposed receiver element is printed on a FR4 substrate with a dielectric constant of 4.7, a thickness of 1.6 mm and a conductor loss of 0.019. Microstrip dipole antenna that is presented here has a wide bandwidth up to 24% bandwidth. The 90 0 hybrid coupler can act as a phase shifter to provide the necessary 90 0 characteristics to operate with I/Q signal for direct conversions. Two schottky diodes (HSMS 8101) are mounted onto each of two coupler's output port to act as a mixer. One kHz sinusoidal signal act as a baseband have been generated and modulated using signal generator. The demodulated signal is detected using direct conversion receiver circuit and the baseband signal at the output ports should be detected using oscilloscope. vi ABSTRAK Tesis ini menerangkan mengenai rekaan padat antena mikrostrip dipole digabungkan bersama 90 0 hybrid coupler, oscillator dan diod untuk penerima Direct .Conversion atau Zero-IF. Frekuensi yang digunakan adalah pada 2.4 GHz dimana ia banyak digunakan untuk aplikasi RF ID. Di dalam rekaan penerima ini, perisian Agilent ADS menggunakan simulasi momentum dan litar telah digunakan untuk menganalisa seluruh struktur litar. Antena microstrip dipole ini mempunyai lebarjalur sehingga 24 %. 90 0 hybrid coupler pula akan bertindak sebagai penganjak fasa, supaya mencapai ciri 90 0 untuk operasi bersama isyarat I/Q. Dua diod Schottky (HSMS 8101) dilekapkan bersama setiap pasangan port keluaran untuk bertindak sebagai pengadun. Satu pin daripada diod itu disambungkan pada hujung port keluaran dan satu pin lagi dibumikan di atas satah bumi. Satu kilohertz isyarat sinus bertindak sebagai isyarat baseband telah dijana dan dimodulat menggunakan penjana isyarat. Isyarat yang telah termodulat kemudian dikesan menggunakan litar penerima Direct Conversion dan isyarat baseband kemudiannya berjaya dikesan pada port keluaran menggunakan osiloskop.

In this paper, we propose a feasible beamforming (BF) scheme realized in media access control (MAC) layer following the guidelines of the IEEE 802.15.3c criteria for millimeterwave 60GHz wireless personal area networks (60GHz WPANs). The proposed BF targets to minimize the BF set-up time and mitigates the high path loss of 60GHz WPAN systems. It is based on designed multi-resolution codebooks, which generate three kinds of patterns of different half power beam widths (HPBWs): quasi-omni pattern, sector and beam. These three kinds of patterns are employed in the three stages of the BF protocol, namely device-to-device (DEV-to-DEV) linking, sectorlevel searching and beam-level searching. All the three stages can be completed within one superframe, which minimizes the potential interference to other systems during BF set-up period. In this paper, we show some example codebooks and provide the details of BF procedure. Simulation results show that the setup time of the proposed BF protocol is as small as 2% when compared to the exhaustive searching protocol. The proposed BF is a complete design, it re-uses commands specified in IEEE 802.15.3c, completely compliant to the standard; It has thus been adopted by IEEE 802.15.3c as an optional functionality to realize Giga-bit-per-second (Gbps) communication in WPAN Systems.

Employing conventional three-phase inverter in variable speed single-phase drive suffers from limited maximum output voltage applied to motor or voltage utility factor (VUF). In this study, a z-source inverter (ZSI) has been used to drive a single-phase induction motor (SPIM). By the proposed topology, VUF and consequently torque speed characteristic of the single-phase motor is improved. The equations for employing ZSI in SPIM drive and modulation method are described. Results of two simulations using conventional inverter and ZSI are presented. The results show that using ZSI leads to an increase in motor electromagnetic torque compared to conventional three-phase inverter due to improved VUF. The experimental results confirm the theory and simulation.

A large number of wireless technologies and networks has been introduced in the telecommunication world during the last few years (e.g., GSM/GPRS, UMTS, HSPA, IEEE 802.11, IEEE 802.16, IEEE 802.20, Bluetooth). Typically those networks coexist in the same area, creating a sort of wireless overlay network able to provide more services, more bandwidth and more coverage to users than networks based on a single technology. The main issue is that many protocols and applications (e.g., TCP, VoIP) are not specifically designed for such a variety of wireless protocols. As a consequence these protocols and applications require a deeper analysis in order to understand their behavior when running over those radio protocols and links. Performance analysis represents a valid method to evaluate such protocols and applications, modeling their behavior and then working on their improvement. An appropriate solution to support performance evaluation of a wireless system and its support to protocols and applications consists in building close-to-real test environments. This paper presents a wireless heterogeneous testbed that allows experimentation of WLANs and cellular networks in a laboratory. It combines emulation components and real equipments in a single experimentation platform, with the flexibility, scalability and repeatability features of an emulated environment and the possibility of testing real equipments, e.g., real mobile terminals or UMTS/HSDPA-WLAN wireless cards and base stations. The paper describes also the assessment and the calibration of the testbed. It presents an extensive comparison with a commercial 3G network. Finally, the paper also presents two case studies in order to highlight the benefits of conducting experimental research in an in-lab fully controlled platform.

In this paper, polarization rotation due to optical waveguide bending is analytically and numerically investigated. It is shown that the process of polarization conversion in the bend strictly depends on the characteristics of the straight waveguide. The strength of polarization coupling linearly increases with the waveguide refractive index contrast, whereas birefringence is responsible for the phase mismatch that limits the conversion efficiency. Waveguides with refractive index profile symmetrical in the direction orthogonal to the plane of the bend do not exhibit polarization rotation. Inside optical ring resonators, polarization rotation induced by waveguide bending is found to be highly enhanced by the cavity effect, which gives rise to strongly frequency dependent polarization rotation and dramatically alters the ring's spectral response. In the case of single-ring phase shifters, polarization rotation is effectively described by means of an approach based on the theory of poles-zeros loci, which straightforwardly provides conditions for complete polarization conversion, also in the presence of birefringence and losses. The detrimental effects caused by undesired polarization coupling on the spectral response of widespread optical devices based on ring resonators are also discussed. From this point of view, birefringence is demonstrated to be beneficial to make optical components less sensitive to the effects of polarization rotation.

Design of a compact planar phase shifter is described that possesses ultra-wideband (UWB) performance. The proposed device is composed of 50 Ω input/output microstrip-lines which are connected to a low-impedance rectangular microstrip patch, and located at close proximity to each other. The common ground-plane incorporates a Corresponding author: F. Jolani ([email protected]).

Benefits of ferroelectric component applications at microwaves is discussed. Experience recently gained in the high-temperature film-production technology has been used for obtaining high-quality ferroelectric tunable components. The disk made from bulk SrTiO 3 single crystal covered with double-sided YBa 2 Cu 3 Y 7 films was used as a high-quality TM 010 mode tunable resonator. Planar structures containing thin film ferroelectric layers: planar capacitor, sandwich capacitor, coplanar line, and fin line have been studied. Modeling dielectric response of low-temperature incipient ferroelectrics (SrTiO 3 , KTaO 3) has been applied for simulation of tunable planar structures. The quality factor of a tunable component (QFCT) is suggested to characterize the validity of the component for practical applications. The highquality planar capacitors are pioneered for the applications. The wide frequency band fin line phase shifter has been studied and simulated. The prospects for applications of ferroelectric planar structures at room temperature is discussed.

Integrated optical cross connects and add-drop multiplexers require low loss polarization independent phase shifting elements. In a composite quantum well, a 0.46 mm phase shifter provides a π/4 phase shift by combining the quantum confined Stark effect (QCSE) and carrier depletion effect. All-optical switching due to state filling effect is also experimentally investigated recently. We investigate whether the discrete energy levels and the high peak absorption in quantum dots (QDs) provide an opportunity for increasing the electrorefraction. The electrorefraction in strained InAs/GaAs and InAs/InP quantum dots (QDs) is explored using a numerical model based on the 4×4 Luttinger-Kohn Hamiltonian. The excitonic states are calculated by matrix diagonalization with plane-wave basis states. We observe that the QCSE sharply increases with the height of the QD and is also optimized for small radius QDs. The QCSE in pyramidal QDs is considerably larger than in squares or cylinders. We finally present large electrorefraction in cone shaped pyramidal QDs. State filling effect in QDs further resulted to an electrorefraction higher than an order of magnitude compared to that by QCSE for an acceptable waveguide absorption loss.

A spectrally resolved white-light interferometric sensor for absolute position measurement based on Hilbert transform is presented. In order to avoid the possible singularities in the standard method obtained during the division of the measured spectral fringes and their Hilbert transform, a novel method is developed. The method is based on the simple mathematical apparatus where the division with zero is avoided by the division of the measured channeled spectrum and its Hilbert transform with envelope of both functions. Both of the divided functions are further differentiated, squared, and summed in order to find the optical path difference in the interferometer and thus the absolute position. The proposed sensing system currently provides unambiguous measurement over a range of 200 μm with a mid range error of better than 17 nm.

Nonlinearities in transmitter circuits, such as power amplifiers, cause degradation in system performance and adjacent-channel spectral growth interference. Polyphase multipath is considered among the techniques that can compensate the nonlinearities, creating a clean output spectrum. However, the polyphase technique requires analog phase shifters that consume considerable power. Aiming at reducing the power consumption, this brief presents a novel multiphase multipath technique with digital phase shifters. The technique is capable of canceling most of the harmonic and intermodulation products produced by a current-output nonlinear circuit to achieve the required linearity. The proposed system has advantages over existing polyphase techniques in power consumption, accuracy, and flexibility. However, it lacks image rejection and local oscillator harmonic cancellation. Detailed analyses and simulations of the new technique are provided to show the effectiveness of the harmonic distortion cancellation.

The new generation of system-on-chip (SoC) incorporates digital, analogue, radiofrequency (RF)/microwave and mixed-signal components. Therefore, novel design methodologies must be developed to direct the design of these mixed-technology systems, which will have to include accurate behavioral libraries of devices and processes. Thus, this paper describes a behavioral modeling approach which generates accurate empirical models for RF/microwave devices and that can be easily integrated into a VHDL-AMS simulator. This approach is applied to a microwave tunable phase shifter and it is illustrated by the development of a VHDL-AMS model library for RF/microwave applications. r

A Fizeau interferometer-based set-up for measurement of surface ÿgure of plane optical surfaces has been discussed. Phase-shifting interferometry has been applied using wedge phase shifter. Technique for elimination of system aberrations has been described. Results are shown for a plane surface. ?

We demonstrate microwave phase shifters based on electrically tunable silicon-on-insulator microring resonators (MRRs). MRRs with different quality factors are fabricated and tested. A continuously tunable phase shift of up to 336 at a microwave frequency of 40 GHz is obtained using a high-quality-factor ( 28 000) MRR with only 1.6-mW power consumption. A quasi-linear phase shift in the range of 0 -204 at 40 GHz with a radio-frequency power variation less than 1.3 dB is also achieved by using a lower-quality-factor MRR.

This article presents a Ku band 360° analogue phase shifter optimized with a genetic algorithm. Varactor diodes are used as the tuning elements. The device presents 360° phase shift on 11% bandwidth. At 12 GHz, the insertion loss is found to be −2.2 ± 0.4 dB. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 283–285, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24944

The design and implementation of a phase shifter based on the substrate integrated waveguide (SIW) technique operating at 10 GHz are presented. The proposed phase shifter consists of a SIW section with two inserted metallic posts. The phase shifting in this configuration is achieved by changing the diameter and the position of these posts. Numerical simulations have been carried out for different diameters and positions, which have shown good agreement with the theory. A parametric study was also conducted to assess the impact of errors made on the diameter and position of the two metallic posts. To prove the concept, prototypes were fabricated and measured. Experimental results agree well with simulations and S11 was better than-14 dB, S21 better than-1.08 dB and the phase error was less than 1.58.

Optical phased arrays represent an enabling new technology that makes possible simple, affordable, lightweight, optical sensors offering very precise stabilization, random-access pointing, programmable multiple simultaneous beams, a dynamic focus/defocus capability, and moderate to excellent optical power handling capability. These new arrays steer or otherwise operate on an already formed beam, as compared to modem microwave phased arrays which both generate a beam and direct it in a specific direction. A phase projile is imposed on an optical beam as it is either transmitted through or refected from the phase shifter array. The imposed phase projile steers, focuses, fans out, or corrects phase aberrations on the beam. The array of optical phase shifters is realized through lithographic palteming of an electrical addressing network on the superstrate of a liquid crystal waveplate. Refractive index changes suficiently large to realize full-wave diperential phase shifts can be effected using low (<IO V ) voltages applied to the liquid crystal phase plate electrodes. High eficiency large-angle steering with phased arrays requires phase shifter spacing on the order of a wavelength or less; consequently addressing issues make I-D optical arrays much m r e practical than 2 -0 arrays. Orthogonal oriented 1-D phased arrays are used to defect a beam in both dimensions. Optical phased arrays with apertures on the order of 4 cm by 4 cm have been fabricated for steering green, red, 1.06 pm, and 10.6 pm radiation. Steering eficiencies of about 60% at 4" and 85% at about 2' have been achieved to date with switching times as short as a few milliseconds in the visible. Fluences of several hundred W/cm2 have been demonstrated at 10.6 pm with nonoptimlly engineered devices. Higher fluences can be handled at shorter wavelengths. Larger apertures are feasible, as is operation at other wavelengths and significantly faster switching times. System concepts that include a passive acquisition sensor as well as a laser radar are presented.

The design of Automatic Generation Control (AGC) system plays a vital role in automation of power system. This paper proposes Hybrid Neuro Fuzzy (HNF) approach for AGC of two-area interconnected reheat thermal power system with the consideration of Generation Rate Constraint (GRC). The advantage of proposed controller is that it can handle the system non-linearities and at the same time the proposed approach is faster than conventional controllers. The performance of HNF controller has been compared with that of both conventional Proportional Integral (PI) controller as well as Fuzzy Logic Controller (FLC) both in the absence and presence of Generation Rate Constraint (GRC). System performance is examined considering disturbance in each area of interconnected power system. .His areas of research include power system transient stability, power system dynamic stability, FACTS, optimisation techniques, distributed generation and wind energy.

We present the use of electrically controlled birefringence in a nematic liquid crystal cell for phase shifting of electromagnetic waves up to terahertz frequencies. This device was operated at room temperature and a maximum phase shift of 4.07 was demonstrated at 1.07 THz when the interaction length was 38.6 m. The driving voltage and corresponding field were 176.8 V (rms) and 589.3 V/cm, respectively.

We demonstrate the polarization-insensitive operation of a Mach-Zehnder interferometer (MZI)-based lithium niobate switch with a silica waveguide polarization beam splitter. The splitter is composed of an MZI with a half wave plate installed in one arm, and exhibits a polarization extinction ratio of more than 15 dB. The switch functions for both polarizations with an extinction ratio of more than 20 dB, a polarization-dependent loss of 0.1 dB and a switching speed of 40 ps.

We study a class of optical circuits with vacuum input states consisting of Gaussian sources without coherent displacements such as downconverters and squeezers, together with detectors and passive interferometry (beam-splitters, polarisation rotations, phase-shifters etc.). We show that the outgoing state leaving the optical circuit can be expressed in terms of so-called multi-dimensional Hermite polynomials and give their recursion and orthogonality relations. We show how quantum teleportation of photon polarisation can be modelled using this description.

A dielectric resonator technique has been used for measurements of the permittivity and dielectric loss tangent of single-crystal dielectric substrates in the temperature range 20-300 K at microwave frequencies. Application of superconducting films made it possible to determine dielectric loss tangents of about 5×10-7 at 20 K. Two permittivity tensor components for uniaxially anisotropic samples were measured. Generally, single-crystal samples made of the same material by different manufacturers or by different processes save significantly different losses, although they have essentially the same permittivities. The permittivity of one crystalline ferroelectric substrate, SrTiO3, strongly depends on temperature. This temperature dependence can affect the performance of ferroelectric thin-film microwave devices, such as electronically tunable phase shifters, mixers, delay lines and filters

Micromachined reflection-type phase shifters with small size and low loss for V-band communication systems are described. Two-and three-bit reflection type phase shifters were designed, fabricated, and measured. The micromachined air-gap overlay coupler and the direct contact type series switches were employed to implement the phase shift and reduce an insertion loss. The phase shift can be obtained by changing the length of the open-ended stubs using the cascaded MEMS switches. The fabricated two-bit phase shifter has a measured phase shift of 0 , 41.5 , 84.3 , and 128.7 with the consecutive actuation of the series MEMS switches. The actuation voltage of the switches is 35 V and the measured switching ON time is 5.1 s. The average insertion loss of the two-bit phase shifter measured 4.1 dB at 60 GHz and the return losses for all phase shift states are better than 11.7 dB from 50 to 70 GHz. The two-bit phase shifter is small, 1.5 mm 2.1 mm. By cascading the two-bit phase shifter and a 180 phase shifter (one-bit), a three-bit phase shifter is realized, which has a phase shift of 265.5 and an average insertion loss of 4.85 dB at 60 GHz. The size of the three-bit phase shifter is 3.2 mm 2.1 mm.

An integrated semiconductor 1 2 5 InP-InGaAsP optical phased-array switch is fabricated and characterized. Using the carrier-induced refractive index change of InGaAsP waveguide, we achieve successful switching to five output ports with less than 60-mA current injection. Wide operating bandwidth covering the entire C-band (1520-1580 nm) and nanoseconds dynamic response are demonstrated, making it potentially applicable to large-capacity wavelength-multiplexed optical-packet-switching routers.

Technology. His research interest includes power system operation and control, electricity market as well as real time modeling and simulation. He is vice chair of IEEE PES career promotion subcommittee and secretary of student activities subcommittee.

The Cascaded-Match Reflection-Type Phase Shifter (CMRTPS) was recently introduced to significantly widen the bandwidth of traditionally narrow band high performance analogue phase shifters. For the first time, a monolithic CMRTPS is realised. A 6.5-13.0GHz phase shifter, with dimensions of 3.0x2.0x0.2mm, was fabricated using standard GaAs founm-y processing. At the 10GHz centre frequency, the measured relative phase shift and insertion loss varied from 0 to 90°and from-3.65dB to-2.63dB, respectively, for a bias potential decreasing from 0 to-7.5V. Here, a maximum measured peak phase error of +-3.69°and a peak amplitude of +-0.63dB were maintained across the octave bandwidth, for all bias levels. In addition, the measured input return loss was approx. 20dB across most of this octave bandwidth.

In radar, planar phased array antenna plays vital role in electronic scanning in the azimuth and elevation direction to the horizon. In most operations using planar phased array both the coordinates of azimuth and elevation, are steered electronically. In this paper a conceptual schematic of a phased array antenna with programmable time delay units has been presented. It is shown that by suitably exploiting the time delay matrix one can have electronic beam rotation around the target axis as required in conical scan. Thus both the elevation and azimuth motors in conical scan system are replaced by electronic scanning. Heuristically, we have selected eight consecutive points for beam rotation in a polygon shape and can also be extended almost circular shape by increasing number of array elements and phase shifter (delays) in the delay matrix. The array requires dual control of phase gradient and individual phase values. The whole array is controlled by microcontroller. This presents exciting possibilities in radar operation.

We present results obtained with a computer-controlled lowcoherence interference microscope featuring a modified optical layout that uses a pair of fast switchable achromatic phase-shifters. This layout makes it possible to use ferro-electric liquid-crystal devices made with readily available FLC materials having a switching angle of 45°, and obtain phase shifts of 0° and ±90°. The use of phase shifts of 0° and ±90° simplifies calculations of the fringe visibility and the fractional fringe-order and yields maximum accuracy.

A review of radio frequency microelectromechanical systems (RF MEMS) technology, from the perspective of its enabling technologies (e.g. fabrication, RF micromachined components and actuation mechanisms) is presented. A unique roadmap is given that shows how enabling technologies, RF MEMS components, RF MEMS circuits and RF microsystems packaging are linked together; leading towards enhanced integrated subsystems. An overview of the associated fabrication technologies is given, in order to distinguish between the two distinct classes of RF microsystems' component technologies; non-MEMS micromachined and true MEMS. An extensive literature survey has been undertaken and key papers have been cited; from these, the motivations behind different RF MEMS technologies are highlighted. The importance of understanding the limitations for realising new and innovative ideas in RF MEMS is discussed. Finally, conclusions are drawn as to where future RF MEMS technology may lead. It is likely that the switch will continue to be the most important RF MEMS component, with future work investigating its enhanced functionality, subsystem integration and volume production. The focus of RF MEMS circuits will shift from the digital phase shifter to high-Q tuneable filters.

The different impedances needed for the suspended coaxial transmission line can be achieved by varying the size of the centre conductor [15]; here, the size of the outer conductor is fixed. The centre conductor of the resulting suspended coaxial transmission line is shown in (a), with the cross-sections of the 50⍀ line and the stubs shown in (b). The input and output of the suspended transmission line, as shown in , consist of 50⍀ sections of transmission line.

To evaluate the influence of a printed wiring board (PWB) with a high coefficients of thermal expansion (CTE) on the thermal deformation of a small outline J-leaded electronic package (SOJ), a newly developed phase-shifting method was applied to moireí nterferometry. This phase-shifting moire´interferometry method uses a wedged glass plate as a phase shifter to obtain displacement fields with a sensitivity of 100 nm/line. This technique also enabled the quantitative determination of strain distributions in all observation areas. Thermal loading was applied from room temperature (25 1C) to an elevated temperature (100 1C), and then the thermal strains of SOJ with and without the PWB were compared. The results showed that the concentrations of the longitudinal strains e xx and e yy became increasingly prominent when mounted on the PWB, and the shear strains g xy were concentrated at the corners of the silicon chip. The values of these strains increased by about 50% when the SOJ was mounted on the PWB. r

This paper proposes a position sensorless control scheme for four-switch three-phase (FSTP) brushless dc (BLDC) motor drives using a field programmable gate array (FPGA). A novel sensorless control with six commutation modes and novel pulsewidth modulation scheme is developed to drive FSTP BLDC motors. The low cost BLDC driver is achieved by the reduction of switch device count, cost down of control, and saving of hall sensors. The feasibility of the proposed sensorless control for FSTP BLDC motor drives is demonstrated by analysis and experimental results.

This paper presents an analysis of the temperature dependent properties and performance of coplanar waveguide transmission lines on Ba 0.5 Sr 0.5 TiO 3 (BST) thin films. Comparison of the temperature dependent permittivity at microwave frequencies with models of heterogeneous ferroelectrics reveals significant physical properties, such as the Curie temperature, Curie-Weiss constant, and statistical defects in the films. The maximum phase shift and tunability are obtained at the temperature where the permittivity is highest.

Optical phased arrays represent an enabling new technology that makes possible simple affordable, lightweight, optical sensors offering very precise stabilization, random-access pointing programmable multiple simultaneous beams, a dynamic focus/defocus capability, and moderate to excellent optical power handling capability. These new arrays steer or otherwise operate on an already formed beam. A phase profile is imposed on an optical beam as it is either transmitted through or reflected from the phase shifter array. The imposed phase profile steers, focuses, fans out, or corrects phase aberrations on the beam. The array of optical phase shifters is realized through lithographic patterning of an electrical addressing network on the superstrate of a liquid crystal waveplate. Refractive index changes sufficiently large to realize full-wave differential phase shifts can be effected using low (

We suggest a theoretical scheme for the simulation of quantum random walks on a line using beam splitters, phase shifters, and photodetectors. Our model enables us to simulate a quantum random walk using of the wave nature of classical light fields. Furthermore, the proposed setup allows the analysis of the effects of decoherence. The transition from a pure mean-photon-number distribution to a classical one is studied varying the decoherence parameters.

This article presents the design of a 6-bit phase shifter in a 0.18-m CMOS technology for X-band phased array radar application. Meandered microstrip lines and compact circuit designs techniques yield a chip with 1.9 mm 2 die area. The fabricated phase shifter demonstrates a typical 15.7 Ϯ 1.1 dB insertion loss and a 4°rms phase shift error at 9.5 GHz. To the author's knowledge, this is the first demonstration of a 6-bit phase shifter using CMOS switches with the lowest die area among reciprocal digital phase shifters at X-band.

A phase sensitive Michelson interferometer based on interference microscope configuration with a polarization adjustment approach is proposed to determine the two-dimensional (2-D) surface profile of optical grating with real time capability. In the proposed method, nonlinear behavior of a PZT phase shifter is avoided by use of polarization stepping and a phase map is developed with the four-bucket algorithm. The phase map is unwrapped to give the true surface profile of the sample. A close agreement of measurements is found between the measured result determined by the proposed method and that determined by an atomic force microscope (AFM). We also analyzed the estimated uncertainty of measurement in the nanometer range for the random fluctuations of the experimental parameters.