Phase Delay Characteristics Research Articles

Relay‐based identification scheme for processes with non‐minimum phase and time delay

This study presents the frequency-domain and state-space approaches for modelling and identification of processes exhibiting non-minimum phase and time delay characteristics. An asymmetrical relay is fed back to unknown process to bring sustained oscillatory responses or limit cycle at the process output. Utilising the relay settings and limit cycle information, a set of mathematical expressions for the identification of process dynamics in terms of non-minimum phase second-order plus time delay, non-minimum phase first-order plus time delay, non-minimum phase integrating first-order plus time delay models is deduced. As compared to the methods reported in recent literature, the proposed set of explicit expressions is completely free from the simultaneous solution of a set of non-linear equations and does not need any prior guess for initial value of the unknown process model parameters. Simulations of benchmark examples from literature and experimental results from coupled tanks system are included to demonstrate the efficacy of the proposed relay-based identification algorithms.

A compact printed ultra‐wideband multiple‐input multiple‐output prototype with band‐notch ability for WiMAX, LTEband43, and WLAN systems

A compact ultra-wideband multiple-input multiple-output (UWB-MIMO) antenna with good isolation and multiple band-notch abilities is developed in this work. It consists of two quadrant shaped monopole antennas backed by ground stubs. A good isolation is achieved due to the two proposed extended curved ground stubs. The frequency rejection for the WLAN system is realized by loading a capacitive loaded loop resonator adjacent to the feed line. The band rejection for the WiMAX and LTE band43 system is achieved by embedding a quadrant shaped CSRR on each radiator's surface. The measured bandwidth of the antenna is 3.06 GHz-11 GHz (|S11| < −10 dB and |S21| < −18 dB) with a band rejection from 3.5 GHz-4 GHz to 5.1 GHz-5.85 GHz, respectively. Time domain performances are investigated in terms of group and phase delay characteristics. Diversity characteristics are evaluated in terms of the envelope correlation coefficient, mean effective gain, and channel capacity loss.

Linear and nonlinear behavior in single-ring resonators

This study has been focused on the linear and nonlinear behavior and investigative in single-ring resonator. Optical fiber ring resonators have great interest due to different applications, especially in communication, secured communication, slow light, fast light and light storage in optical buffers. There are many proposed applications of optical ring resonators. Optical fiber ring resonators can be readily constructed from standard optical fiber components, which allow their properties to be studied in a systematic manner. In this paper, we describe our studies of the optical transmission, intensity, shift phase and group delay characteristics of a family of such devices. In this case, Gaussian beam has been used as an input pulse inside to microring resonators. In this paper, transmission, intensity, shift phase and group delay characteristics of device have been investigated. It has been compared together in different coupling coefficients in frame of linear and nonlinear.

Dual-frequency phase shifter deploying complementary split-ring resonator

Phase shifters are indispensable microwave components. In this paper, a dual-frequency, passive, analog, and reciprocal phase shifter is proposed, deploying the phase-delay characteristics of complementary split-ring resonator (CSRR). A transmission line is loaded with a pair of CSRR in the ground plane and the phase variations are compared with an ideal transmission line. The proposed phase shifter operates in the industrial, scientific and medical (ISM) and wireless local area network (WLAN) bands, providing a phase of 180° at 2.4 GHz and 90° at 5.4 GHz for beam steering applications.

A THEOREM ON REPEATED FILTERING

Repeatedly passing a signal through a low-pass filter may resemble using a Gaussian or hyper-Gaussian filter. Conditions are established for this resemblance. A theorem on approximation of Gaussian and hyper-Gaussian filters by a cascade of simple filters is established and the corresponding phase and group delay characteristics are analyzed. The theorem and the analysis are exemplified by cascading moving-average filters and the first-order Butterworth filters.

Constructing a two bands optical code-division multiple-access network of bipolar optical access codecs using Walsh-coded liquid crystal modulators

We propose and experimentally demonstrated the two bands optical code-division multiple-access (OCDMA) network over bipolar Walsh-coded liquid-crystal modulators (LCMs) and driven by green light and red light lasers. Achieving system performance depends on the construction of a decoder that implements a true bipolar correlation using only unipolar signals and intensity detection for each band. We took advantage of the phase delay characteristics of LCMs to construct a prototype optical coder/decoder (codec). Matched and unmatched Walsh signature codes were evaluated to detect correlations among multiuser data in the access network. By using LCMs, a red and green laser light source was spectrally encoded and the summed light dots were complementary decoded. Favorable contrast on auto- and cross-correlations indicates that binary information symbols can be properly recovered using a balanced photodetector.

Extremely compact phase delay line with CTSRR loaded transmission line

Phase delay characteristics of the complementary triangular split ring resonator (CTSRR) loaded transmission line with capacitive stubs are presented. The phase responses of a reference microstrip transmission line and a transmission line with capacitive stubs, loaded with the CTSRR on the ground plane, are compared. The practical results show that the CTSRR loaded transmission line provides four times more phase delay when compared with a reference transmission line, and thus the proposed configuration provides a 76% transmission line length reduction.

Measurement of thin conductive dielectric coating material parameters in a high noise environment

The tolerances of very thin, possibly conductive dielectric coating material parameters measured using the wideband free space transmission loss measurement technique in a high noise environment was investigated. The advanced postprocessing algorithm that improves those tolerances has been developed. This algorithm allows extracting thin coating material parameters with practically acceptable accuracy even when the level of systematic and random measurement noise is much greater than the level of transmission loss and insertion phase delay characteristics of the tested material sample. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013.

Electromagnetic performance analysis of novel multi-band metamaterial FSS for millimeter wave radome applications

The electromagnetic design and performance analysis of dual/ multi-band metamaterial frequency selective surface (FSS) structures have been carried out for radome applications in microwave and millimeter wave frequency regimes. The proposed metamaterial FSS structure, consisting of cascaded MNG (mu-nega -tive) and DPS (double positive) layers, exhibits dual-band transmission responses at V-band and W-band. Excellent transmission efficiency (more than 95%) has been obtained over the frequency range 45.8-53.1 GHz at first resonance, and from 93.0-97.1 GHz at second resonance. The incorporation of additional DPS layer to the proposed metamaterial-FSS structure facilitates multiband bandpass characteristics at 30 GHz (in Ka-band), 64 GHz (in V-band), and 93.6 GHz (in W-band). The reflection and insertion phase delay characteristics are also analyzed at high incidence angles in view of streamlined airborne nosecone radome applications.

Small-Space Microphone Array Fractional Delay Algorithm Based on FIR Filter for Cochlear Implant

Directional speech enhancement of signals from microphone arrays is an effective way to improve speech recognition for cochlear implant users. The strict implant size limitation results in a short distance between microphones. The fractional delay problem due to the short distance between microphones is solved by a maximal flat (Maxflat) finite impulse response (FIR) filter, using the Maxflat error criteria at a low frequency containing most of the speech information and energy. The fractional Maxflat FIR filter approximates the ideal digital fractional filter at the magnitude response, phase response, and phase delay characteristics, and is also very low order. The results demonstrate that the Maxflat FIR filter accurately and effectively solves the fractional digital delay and is very suitable for real-time speech processing in practical cochlear implant products.

550 流体力が作用する案内板の振動応答に関する研究

This paper presents a flow-induced vibration of guide plates with a large tilt angle in relation to the flow direction. A wind tunnel tests are carried out for measurement of the vibration and pressure characteristics of the guide plates. The measured data of pressure include random and acoustic resonance components. The vibration of the guide plates includes the components both with the natural frequencies of the plates and the acoustic resonance frequency. We have proposed a vibration response analysis technique for an FE model, considering both the spatial correlation and phase delay characteristics defined by the measured pressure. It is verified that the present technique is valid for the experimental results.

Influence of phase delay profile on diffraction efficiency of liquid crystal optical phased array

The hardware structure and driving voltage of liquid crystal optical phased array (LCOPA) devices determine the produced phase delay characteristics. The phase delay profile influences directly the device's diffraction efficiency. In this paper, a sawtooth-shaped phase delay model of LCOPA was proposed to analyze quantitatively the influence factors of diffraction efficiency employing Fourier optics theory. Analysis results show that flyback region size is the main factor that affects diffraction efficiency. The influence extent varies with different maximum-phase-delays and grating periods. There exists an optimized curve between maximum-phase-delay and flyback region, and between maximum-phase-delay and grating period, individually. The smaller the grating period is or the larger the flyback region is, the more evident the optimization effect becomes, and the maximum increase ratio is up to 16%. Some feasible experiments were done to test theoretical analysis, and the experimental results agreed with the analysis results.

An OFDM-based wireless ATM transmission system assisted by a cyclically extended PN sequence for future broad-band mobile multimedia communications

An orthogonal frequency division multiplexing (OFDM)-based wireless asynchronous transfer mode (ATM) transmission system is described that is suitable for the future broad-band mobile multimedia communications. In the proposed system, guard symbols, which are cyclically extended by repeating the information symbols, are inserted before and after serial-to-parallel converted wireless ATM data symbols for OFDM transmission. These symbols are used for both wireless ATM frame synchronization and deciding the discrete Fourier transformation (DFT) start point at the receiver. A cyclically extended pseudorandom noise (PN) sequence is inserted into some of the OFDM transmission subchannels at fixed intervals and used to estimate the phase rotation, frequency offset, and delay characteristics. The proposed system does not use symbol-by-symbol guard-interval insertion or removal circuits, as do conventional OFDM systems. With this system, it is easy to estimate the phase rotation, frequency offset, and delay characteristics and to synchronize wireless ATM cells. Computer simulation showed that the bit error rate (BER) performance of the proposed system is better than that of a conventional symbol-by-symbol OFDM system.

Envelope delay characteristics of a voice grade telephone circuit

An efficient method is proposed for deriving the phase and group delay characteristics of a voice grade telephone network from its amplitude spectrum. The method is based upon decomposing the amplitude spectrum into piecewise-linear components. From these components first the phase and then the envelope delay of the system over the frequency spectrum are computed. An example has been presented to demonstrate the implementation of the proposed algorithm.

Analysis of filter bank transfer functions

Parallel filter banks are used for realtime signal analysis, e.g. spectrum or speech analysis. The problem to be solved in filter bank realisation is to achieve as high selectivity of individual filters as possible and simultaneously meet the amplitude and phase characteristic specification of the bank. A design method for a bank of analogue filters is presented in the paper. An algorithm for the analysis of the amplitude, phase and group delay characteristics of the bank is given. The applicability of various types of transfer function (Bessel, Scanlan, Coung-Neirynck, Butterworth and Cheby̅chev linear phase approximation) is investigated. To study the other possibilities of realising a filter bank, the so-called modified Scanlan filter has been formed by applying an automated optimisation procedure. This filter retains the performance of the Scanlan filter, but the Q factor of the critical pole pair is reduced. The examples of uniform and constant percentage bandwidth filter banks are presented to illustrate the comparative characteristics of filter banks designed on the basis of these six approximations with 12th-order filters.

Asymmetrically truncated SAW transducers

A symmetrically designed finite impulse response (FIR) SAW transducer has linear phase characteristics and symmetry in the bandpass response. An analysis is presented which shows that a linear phase SAW bandpass filter retains symmetry about center frequency in its magnitude, phase, and group delay characteristics when asymmetrically truncated about the center of the transducer spatial array. While passband amplitude ripple characteristics can often be improved, a trade-off occurs in group delay and phase behavior. The degradation in group delay and linear phase is not severe, however, and the technique may be applied to conserve overall substrate dimension parallel to the propagation direction, consistent with design constraints on the filter performance. Furthermore, both the input and output transducers may be modified in a complementary fashion so that overall linearity in group delay and phase is retained. Experimental confirmation is presented.

Use of Attenuation and Phase Delay Characteristics of SAW to Measure Air-Gap Height (Technical Notes)

The attenuation and phase delay characteristics of a SAW which has been perturbed by a metallic plane above the surface of a piezoelectric delay line have been theoretically computed and experimentally measured. These measurements provide a diagnostic tool for determining the height of an air gap and for determining the minimum achievable air gap for a particular supporting structure.

Nonlinear and Large-Signal Characteristics of Millimeter-Wave IMPATT Amplifiers

Experimental results obtained with millimeter-wave IMPATT amplifiers are presented. Nonlinear and large-signal characteristics of stable IMPATT amplifiers and injection-locked IMPATT oscillators are described. Amplifier circuit configuration, diode characteristics, and measured effects of bias current, temperature, and large-signal level on gain, bandwidth, power saturation, and phase-delay characteristics are discussed in detail.

Phase Equalization Problems in a Phased-Array Transmitter

Current RADAR systems employing programmed multiple antenna feeds to orient the antenna beam electronically require large numbers of parallel channels operating simultaneously with nearly identical phase-delay characteristics. These channels include active devices such as microwave amplifiers for which phase-delay, as well as gain and power output, must be identical to accomplish high pointing accuracy and maximum power addition. When the system is required to operate over a wide frequency band, all channels must track in phase. This paper describes problems encountered in the development of a prototype transmitter requiring multiple channel phase-delay equality. A new medium power pulsed TWT is described and measurements of its electrical length are discussed. Computer programming which reduced the vast amount of phase information derived from this development is described.

Transient Response of Multistage Video-Frequency Amplifiers

The response to a Heaviside unit voltage is set forth as the most logical and relevant criterion of the fidelity of video-frequency amplifiers. The part of the transient response that is governed by the high-frequency amplitude and phase-delay characteristics of amplifiers may be approximated closely by the steady-state response to a square wave having a suitable period and thus may be expressed in a Fourier series. Simplicity and rapidity of numerical calculation are the outstanding advantages of the steady-state formulation. As an illustrative example of the method the transient response of several multistage compensated resistance-coupled amplifiers are computed. Considerable data helpful in the design of amplifiers of this type are presented. It is concluded: (1) The wave-shape distortion of a Heaviside unit voltage is accumulative as the number of stages is increased. (2) The value of the damping constant K= RVL/ C should lie between 1.51 and 1.61. (3) The resonant frequency fo = 1/( 2r, rVLC) determines the slope of the wavefront of the transient response. R is load resistance; C is the total shunt capacitance; and L is the compensating inductance in series with R. It is proposed that the oscillographic response of video-frequency amplifiers and the associated transmission apparatus to a square wave be considered as a part of performance tests of future television systems.