Showing papers in "Iete Journal of Research in 1965"
TL;DR: In this paper, the second method of Liapunov is used to determine asymptotic stability of non-linear feedback control systems with hardspring characteristic as nonlinear element.
Abstract: The second method of Liapunov is used to determine asymptotic stability of non-linear feedback control systems. The paper deals with second and third order control systems with hardspring characteristic as non-linear element and determines stability by simplified stability criteria from the development of Liapunov functions. The above systems have been simulated in an analogue computer and establish the results from stability criteria.The above Liapunov method fails in certain practical cases where the open loop transfer function of a control system has a pole at the origin. A pole shifting technique has been used in this paper to extend the applicability of the method.
23 citations
TL;DR: In this paper, the Fejer curves of percentage modulation impressed on the wanted echo as a function of the time delay between the disturbing ground pulse and the wanted ground pulse were obtained near noon during January 1963 (local summer).
Abstract: The new pulse interaction technique introduced by Fejer (1955) has been employed at Armidale (lat. 30°32'S; log. 151°38'E) to investigate the lower ionosphere. High sensitivity of measurement of the impressed modulation on the wanted echo, at least 0.005 per cent, was achieved by the use of a powerful transmitter of about 200 kW. peak-power and high-gain aerial systems for each of the disturbing, the wanted transmitters and the receiver. The receiving system consisted of a high-gain narrow band amplifier and a phase-sensitive detector. The ordinary mode of propagation was used for both the disturbing and the wanted echoes.The Fejer curves of percentage modulation impressed on the wanted echo as a function of the time delay between the wanted echo and the disturbing ground pulse were obtained near noon during January 1963 (local summer). Some of these curves were analysed using the wave-interaction theory originally developed by Bailey (1937, 1938) and the standard magnetoionic theory. An electron ...
4 citations
TL;DR: In this paper, the propagation characteristics of an electromagnetic wave traversing a medium which has periodically varying properties were evaluated, and it was found that the outcoming wave gets modulated in amplitude as well as in frequency.
Abstract: An attempt is made to evaluate the propagation characteristics of an electromagnetic wave traversing a medium which has got periodically varying properties. Maxwell's equations are solved for a medium whose dielectric constant and conductivity have got small a.c. terms superimposed over their respective d.c. terms, and the attenuation and phase constants are evaluated. It is found that the outcoming wave gets modulated in amplitude as well as in frequency. When the a.c. terms vanish, the attenuation and phase constants reduce to the classical values.
3 citations
TL;DR: In this article, a filter type of up-converter Parametric Diode Amplifier operating on the sum-mode at a signal frequency of 755 Mc/s.
Abstract: This paper gives an account of the studies carried out on a filter type of up-converter Parametric Diode Amplifier operating on the sum-mode at a signal frequency of 755 Mc/s. and pump frequency of 9805 Mc/s. The diode used was a Kita diode type GSB-1A with a cut-off frequency of 60 kMc/s. At the output of the amplifier, a bandpass filter has been provided to select the signal at the output frequency and a band rejection filter to eliminate the pump frequency. The paper gives a brief account of the amplifier designed and also of the measurements carried out.
2 citations
TL;DR: In this article, the authors derived the characteristic equation for the surface wave launched on a cylindrical conductor loaded periodically with metal disc by taking into account the existence of both the fundamental and the space harmonics on the structure and only the TEM wave inside the grooves.
Abstract: The characteristic equation for the surface wave launched on a cylindrical conductor loaded periodically with metal disc has been derived by taking into account the existence of both the fundamental and the space harmonics on the structure and the existence of only the TEM wave inside the grooves. A theoretical relation for calculating the band pass characteristics of the structure as functions of groove depth, width and spacing of the discs has also been derived.
2 citations
TL;DR: An exponential transmission line is represented by a finite network and the error that results from such a truncation is estimated and a possible means of reducing the error, thereby increasing the frequency coverage.
Abstract: In this paper, an exponential transmission line is represented by a finite network. The error that results from such a truncation is estimated. A possible means of reducing the error, thereby increasing the frequency coverage, is also indicated.
2 citations
TL;DR: In this article, a four-port X-band junction waveguide circulator and a field displacement type isolator are described, which has a bandwidth of 1·5 kMc/s for less than 1 db insertion loss and greater than 20 db. isolation.
Abstract: This paper describes a four-port X-band junction waveguide circulator and an X-band field displacement isolator. The circulator employs a right angled H-type junction of two X-band waveguides. A full height cylindrical post of R-4 ferrite surrounded by a full height teflon cylinder is symmetrically placed at the junction. Hitherto, no 4-port waveguide circulator using this ferrite-dielectric condiguration has been reported in the literature. This circulator has a bandwidth of more than 500 mc/s. Maximum isolation approaches 40 db. and minimum insertion loss is negligible (less than 0·2 db.). Effects of dielectric loading on the circulator performance are also presented.This paper also describes an X-band field displacement type isolator which has a bandwidth of 1·5 kMc/s. for less than 1 db. insertion loss and greater than 20 db. isolation.
1 citations
TL;DR: In this paper, the authors describe the designs of the helical couplers and the coupled-helix attenuator developed for a medium-power, S-band, travelling-wave amplifier tube.
Abstract: The paper describes the designs of the helical couplers and the coupled-helix attenuator developed for a medium-power, S-band, travelling-wave amplifier tube.The helical couplers, to be used for coupling power into and out of the tube, have been designed to give a good broad-band characteristic, VSWR ⩽ 2·0 from 2·00 to 4·00 Gc/s. This has been achieved in spite of the fact that the ratio of the coupler and main helix diameters is greater than 1·8 (b/a = 2·0).The coupled-helix attenuator that has been developed has an attenuation generally ⩾ 35 db. over the 2·00–4·00 Gc/s. band, with values exceeding 50 db. over several hundred megacycles.
1 citations
TL;DR: In this paper, the electron density distribution in a cylindrical plasma with or without a static axial magnetic field is investigated in the case of the plasma placed coaxially in a microwave cavity by determining the resultant changes in the resonant frequencies of the cavity for different modes.
Abstract: The electron density distribution in a cylindrical plasma with or without a static axial magnetic field is investigated in the case of the plasma placed coaxially in a microwave cavity by determining the resultant changes in the resonant frequencies of the cavity for different modes. The change in the resonant frequency has been calculated, using a perturbation theory, for each of the modes, TM010, TM020, TM110 and TM120. This has been carried out in terms of the average electron density in the plasma for its different radii and for a number of typical density distributions. The frequency change, electron density and plasma radius are all given in suitable normalized forms so that the results are applicable in general. It is shown how these results can be used in practice for determining the electron density distribution.
1 citations
1 citations
TL;DR: In this paper, a circulator and an isolator for operation in X-band region of microwave frequencies have been designed and fabricated from indigenous materials employing ferrites, and the measurement techniques and the results achieved for these low power devices are presented.
Abstract: A circulator and an isolator for operation in X-band region of microwave frequencies have been designed and fabricated from indigenous materials employing ferrites. The measurement techniques and the results achieved for these low power devices are presented.
TL;DR: In this article, an experimental X-band Y-circulator with a cylindrical ferrite post placed at the center of the Y-junction in a direction parrallel to the E-vector is described.
Abstract: An experimental X-band Y-circulator is described. A cylindrical ferrite post, 0·24 in. diam. and 0·4 in. long is placed at the centre of the Y-junction in a direction parrallel to the E-vector. Pole pieces for providing d.c. magnetic field are in contact with the ferrite post. Insertion loss, isolation and input VSWR have been measured as a function of frequency and magnetic field. At 11·8 kMc. an isolation of 34 db, and an insertion loss of 0·6 db. have been obtained. The frequency band over which the isolation is more than 20 db. is about 400 Mc/s. and increases to 550 Mc/s. by surrounding the ferrite post with a polystyrene cylinder of outer diameter 0·35 in. The effect of changing the diameter of the post and that of the dielectric cylinder has also been investigated.
TL;DR: In this article, the design and development of a semiconductor diode parametric amplifier at the L-band was described, which is a single-port device operating in the quasi-degenerate mode.
Abstract: This paper describes the design and development of a semiconductor diode parametric amplifier at L-band. It is a single-port device operating in the quasi-degenerate mode. Results are given for a single-tuned amplifier, with two different diodes. Also described are the effects on the bandwidth by the inclusion of one additional resonator in the signal circuit. The parametric amplifier has a gain bandwidth product which is as good as for other amplifiers in L-band, reported in the literature.
TL;DR: In this paper, an analysis of sporadic E during day-time and night-time was carried out from stations distributed over a wide range of latitudes representing the polar, the auroral, the temperate and the equatorial zones.
Abstract: This paper deals with an analysis of sporadic E during day-time and night-time. Data during the year 1958 from stations distributed over a wide range of latitudes representing the polar, the auroral, the temperate and the equatorial zones have been considered. The occurrence of Es changes from a day-time to a night-time phenomenon towards higher latitudes; however, night-time occurrence of Es is more for an auroral station than for a polar station. The day- and night-time difference of the most probable fEs value is low for polar and auroral stations and is high for equatorial station. At temperate stations this difference has an intermediate value. The cumulative distribution of Es shows that Phillips rule is applicable above the most probable fEs value for day-time and night-time separately at any place.
TL;DR: In this article, the design considerations of a hole-conduction induced channel metal-oxide-silicon transistor are discussed and various processes and details for the fabrication of such a device are described.
Abstract: The design considerations of a hole-conduction induced channel metal-oxide-silicon transistor are discussed. Various processes and details for the fabrication of such a device are described.
TL;DR: A simple process of selectively etching the base and emitter areas by the use of photo-etch resist technique (photo-etching process) has been evolved and discussed in detail as mentioned in this paper.
Abstract: Oxide masking and photo-etching are some of the most important techniques used in the production of silicon planar transistors and semiconductor integrated circuits. The combination of these two techniques makes it possible to get diffusion at the exactly specified base and emitter areas.Silicon oxide is grown by passing steam over silicon slices heated to a temperature of 1000–1250°C. The thickness of silicon oxide growth has been measured by oxide wedge formation and the use of optical methods. A number of experiments have been performed to show the actual relationship between the thickness of the oxide layer grown and time, temperature and resistivity of the starting material.A simple process of selectively etching the base and emitter areas by the use of photo-etch resist technique (photo-etching process) has been evolved and discussed in detail.
TL;DR: In this article, an analytical study of time comparisons between various Solar Flare effects such as SIL, SEA, SWF and that of an optical flare has been made, and a comparative study of the times of growth and those of decay of the effects has also been made.
Abstract: The paper deals with an analytical study of time comparisons between various Solar Flare effects such as SIL, SEA, SWF and that of an optical flare. A comparative study of the times of growth and those of decay of the effects has also been made. The most probable value of the time of growth of an optical flare and that of an SCNA is found, to be 5 min. whereas that for an SIL and an SEA is 7 min. The most probable value of time of decay of an optical flare, SIL and SCNA is found to be 14 min. and that of an SEA is 24 min. An attempt has been made to explain these phenomena in terms of relaxation and recombination processes in the ionosphere.
TL;DR: In this article, a compact Log-periodic V antenna has been developed for use in the frequency range 50 to 100 Mc/s. The antenna can be successfully used both for horizontal and vertical polarization.
Abstract: A compact Log-periodic V antenna has been developed for use in the frequency range 50–100 Mc/s. The radiation patterns and forward gain are uniform throughout the frequency coverage of the antenna. The experimental model gives a directive gain of 6 db. and a front to back ratio better than 15 db. Tests have shown that the antenna can be successfully used both for horizontal and vertical polarization. Details of the characteristics and fabrication of the antenna are discussed.
TL;DR: In this article, a simplified method is adopted to obtain approximate theoretical values of the transmission loss (T.L.) for three types of partition walls, a solid brick wall, a brick cavity wall and a double wall plywood panel have been tested.
Abstract: Results of the measurement on sound insulation of a few partition walls are presented. The sound insulation has been measured in the transmission-reverberation chamber of this Institute. The results are compared with theoretical predictions. A simplified method is adopted to obtain approximate theoretical values of the transmission loss (T.L.).Three types of partition walls, a solid brick wall, brick cavity wall and a double wall plywood panel have been tested. The experimental values of transmission loss of the brick cavity wall is found to be lower than the computed values. This is due to sound transmission through the wire-ties bridging the two panels. The transmission loss of a single thin panel of plywood is too low to meet the insulation requirements. Sound insulation of such panels can be increased by using two panels with a little air space in between. An absorbent material loosely filled in the cavity further improves the transmission loss.
TL;DR: In this paper, the design of waveguide components is discussed and a detailed discussion of the design process is presented, as well as a detailed analysis of the waveguide component design.
Abstract: (1965). The Design of Waveguide Components. IETE Journal of Research: Vol. 11, No. 5, pp. 156-164.
TL;DR: In this article, the development of high resistivity microwave ferrites having the general composition Ni1-xCuxFe1·9Mn0·02O4 has been described.
Abstract: The development of high resistivity microwave ferrites having the general composition Ni1-xCuxFe1·9Mn0·02O4 has been described. Three different compositions corresponding to x = 0, 0·2 and 0·4 have been attempted. The reasons for selecting these particular compositions in the light of their microwave properties have been discussed. Most of their relevant parameters, e.g. the d.c. resistivity, curie temperature, bulk density, saturation magnetization, max. permeability, microwave permittivity and permeability have been determined with a good accuracy. The samples obtained from the compositions corresponding to x = 0·2 and x = 0·4 have been tried in isolator structures and have shown satisfactory characteristics. In addition, as the values of curie temperature measured for these compositions turn out to be very high, these materials offer a good potentiality for the development of high power ferrite devices.
TL;DR: In this article, a simple method using a stripline resonator is described for measuring the dielectric permittivity, linewidth and components of tensor permeability of ferrites in the frequency range 30-6300 Mc/s.
Abstract: A simple method using a stripline resonator is described for measuring the dielectric permittivity, linewidth and components of tensor permeability of ferrites in the frequency range 30–6300 Mc/s The ferrite parameters are evaluated from only two measurements, the cavity frequency and Q The resonator consists of a length of stripline, short circuited at both ends, which may be excited at various frequencies from 300 to 6300 Mc/s or loaded with dielectric to lower the resonant frequency as far as 30 Mc/s It is used in conjunction with a swept frequency test bench
TL;DR: In this article, the results of polarization studies with reference to four aspects of ionospheric propagation are presented and the observed polarizations of pulsed radiowaves suffering successive reflections between the ground and the ionosphere confirm the deductions from the magneto-ionic theory.
Abstract: The results of polarization studies with reference to four aspects of ionospheric propagation are presented. The observed polarizations of pulsed radiowaves suffering successive reflections between the ground and the ionosphere confirm the deductions from the magneto-ionic theory. The polarization characteristics of echoes resulting from M-type reflections are described. Polarization measurements in relation to the group delay of the echoes show that there is no dependence whatsoever for the polarization of echoes on their group delay. Measurements of well-resolved magneto-ionic components on ionospherically disturbed days show no deviations of the polarizations from the normal values.
TL;DR: In this article, a wide band signal generator using reflex klystron and velocity modulated oscillator valves in coaxial cavity resonators is described, which has a calibrated frequency scale, a frequency stability ± 0·002 per cent after 30 min. warm up, output by a calibrated (0-120 db.) attenuator, built in power meter, modulation square wave 200-4000 c/s.
Abstract: Results of the design and development work on wide band signal generators using reflex klystron and velocity modulated oscillator valves in coaxial cavity resonators are reported. For comparison, latest developments and trends in commercial signal generators are mentioned. Two models of signal generators built by the authors are described. One of them uses the velocity modulated oscillator valve (3–4·2 Gc/s.) and the other uses a reflex klystron (2–4·2 Gc/s.). Details of electronic circuits oscillator cavity, tuning, tracking modulation and output calibration are given. These signal generators have a calibrated frequency scale, a frequency stability ±0·002 per cent after 30 min. warm up, output by a calibrated (0–120 db.) attenuator, built in power meter, modulation square wave 200–4000 c/s. frequency modulation in case of reflex klystron and low R.F. leakage.
TL;DR: In this paper, the design equations for calculating the values of input-feedback impedances providing multipath feedback across one operational amplifier and capable of simulating a particular form of a sixth order linear transfer function using only a single operational amplifier are given.
Abstract: In this article the author has given the design equations for calculating the values of input-feedback impedances providing multipath feedback across one operational amplifier and capable of simulating a particular form of a sixth order linear transfer function using only one operational amplifier.
TL;DR: In this article, a general procedure for developing network structures capable of realizing minimum positive real (pr) functions of any order is given, and conditions on the coefficients of given Z(s), bicubic or biquartic, so that it is realizable by any of these networks, are derived and the values of the elements of the network are also found out in terms of the coefficient of Z(S).
Abstract: Networks containing five and six elements and capable of realizing minimum bicubic and biquartic positive real function having ReZ(jω) = 0 at one positive real frequency are presented.Van Valkenburg and Foster have derived six networks, two five-element and four six-element for the realization of minimum biquadratic impedance functions. In this paper it is shown that these networks can realize minimum bicubic impedance functions as well. It is also observed that the four six-element networks due to Foster can realize minimum biquartic impedance functions.Kim has given a general procedure for developing network structures realizing minimum positive real (pr) functions of any order. This procedure gives four six-element networks capable of realizing biquartic functions.Conditions on the coefficients of given Z(s), bicubic or biquartic, so that it is realizable by any of these networks, are derived and the values of the elements of the network are also found out in terms of the coefficient of Z(s).Co...