The contribution of the upper and lower sidebands of a suppressed carrier modulated signal to the output of a general network is examined. The envelope of the output is shown to be simply derived from graphical transformations of the frequency-response locus on the complex plane.
Westervelt and Bellin and Beyer have studied the scattering of intermodulation frequency sound waves arising from the nonlinear interaction of two collimated and coincident plane waves of sound of different frequencies. This work is extended to account for the finite aperture formed by the cross-section of the column; experimental results are compared with those obtained theoretically and with Bellin...
This letter describes a method for improving the stability of the centre frequency of an unstabilised frequency modulated oscillator by replacing it with a crystal-controlled frequency. The process also produces a 2:1 increase of frequency deviation but is limited to frequency-modulating waveforms which possess odd symmetry within each repetition period.
Experimental results are presented which show that parametric action can arise in transistors, owing to pumping of the collector-base diode. An increase in gain can be obtained when a u.h.f. pump is applied to an h.f. amplifier and high conversion gain in a u.h.f.-h.f. downconvertor. Noise performance of an h.f. amplifier can also be improved by pumping.
A description is given of a form of waveguide circuit operated over a frequency range of 30?40 Gc/s and incorporating a number of bends having only a 4 in radius of curvature; it is demonstrated to transmit successfully amplitude modulated television pictures and sound side by side with short microwave pulses. Details of circuit arrangements and modulation technique are given.
Impedance is measured by sampling the voltage and current magnitudes. The sampling period is 50?s, and the point at which sampling takes place is measured from either the current or the voltage zero. Compound impedance characteristics can be achieved by sampling at a number of points in each halfcycle.
An investigation of the output of a microwave crystal mixer at image frequency is described. A curve is presented showing the dependence of image output on i.f. termination. This curve indicates an operating region where mixer performance is insensitive to image termination.
A unified approach to electronic, magnetic and dielectric nonparametric amplifying devices is presented. The word `nonparametric? is used in this note to describe a device with an amplifying junction essentially independent of the parametric coupling and especially of any resonance phenomena of a circuital or field nature.
The dominant circularly symmetric TM surface-wave mode on a Goubau wire immersed in an isotropic plasma is shown to have a low-frequency cutoff, in contrast to its free-space counterpart, for which the propagation extends down to zero frequency.
A general proof using a quantum argument is presented of the Manley?Rowe relations, which provide information on power transfers between different frequencies arising in the circuits of parametric amplifiers and related devices.
This note states and proves a duality theorem in combinatorial switching. The relationship between AND?OR, majority and threshold logics and the property of self duality in majority logic are indicated on this basis.
The poles and zeros of high-Q-factor two-terminal networks can be determined by measuring the poles and zeros of the transfer function of a simple ladder two terminal transmission network. Transmission networks are divided into two groups. General relations between transmission-network transfer functions and measured network immittance functions are obtained.
The problem of ferromagnetic resonance in the presence of domain structure is reformulated, and the resonance relations are calculated. These are in agreement with earlier calculations by Artman2 by a different formulation. The analysis is then extended to the spinwave modes of the system and the parallel-pump instability.
Negative-impedance convertors for lowpass active RC filters must respond down to zero frequency; any attendant drift is unwelcome. A relatively simple circuit is described wherein a balanced input stage feeds an unbalanced output stage, which, in turn, feeds back to both input terminals in the same phase.
A method is presented whereby transfer functions of type 1 and other control systems can be determined from restricted frequency-response test data. Practical extensions to the method are given, involving the use of Bode diagrams or gain/phase plots with angular frequency as a parameter.
Three new realisations of a negative impedance convertor are proposed. Two of them are of the voltage-inversion type, and the other is of the current-inversion type. In order to satisfy the necessary conditions required of a negative-impedance convertor, certain constraints are imposed on the choice of circuit elements. These conditions are briefly discussed. The proposed new circuits have not been...
A dielectric rod enveloped in gaseous plasma can act as a supporting structure for electromagnetic surface waves. The dielectric constant of the plasma and hence the electron number density in the vicinity of the rod may be determined from measurements of the phase-change coefficient of the EH11 mode supported by the plasma-clad rod. Measurements of radial density distribution have been carried out...
A design for an image-convertor high-speed shutter in the range of T = 5?10?11s is proposed, in which the electron beams of the image convertor will bypass a mask to make the shutter open. In order to get an extremely short sweep time, corresponding to short exposure time, the deflection systems will be built as delay lines.
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