Rieke Diagram Research Articles

Effect of reflection on gyrotron operation

The effect of wave reflection on the single-mode operation of a gyrotron is investigated with the help of Rieke diagrams. For this purpose, a set of self-consistent equations describing the beam-field interaction is solved, taking into account the effect of the electron beam and the reflection coefficient on the frequency and RF field profile.

Source-pull/load-pull oscillator measurements at microwave/MM wave frequencies

A six-port reflectometer with variable test port impedance over 2-6 GHz was designed, built, and tested. The potential use of this reflectometer is in large signal characterization of negative resistance devices and oscillators. Experimental source-pull/load-pull measurements on a commercial oscillator (Rieke diagram) were performed using this reflectometer over the entire Smith chart.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Rieke diagrams for gyrotrons

Rieke diagrams provide a useful way of estimating the effect of reflections from the window on gyrotron performance. In some cases, a small change in the reflection coefficient can have a large effect on the output power and on the resonator wall losses. Rieke diagrams can also be useful in determining whether or not a mode will oscillate at all for a given set of parameters and reflection coefficieat.

Graphical analysis of oscillator stability and noise in several kinds of circuits

AbstractTo achieve increased output and frequency stability in solid‐state oscillation it is necessary to reduce the oscillator noise. Measures that may be employed to achieve this include operation of a number of oscillators in parallel, external injection locking, self‐injection locked operation or a combination of such measures. The purpose of this paper is to clarify the nature of the mechanism which causes improved stability or improved noise characteristics due to injection‐locked operation and to develop an intuitive grasp of the stability and noise characteristics of such complex oscillator circuits. In the analysis technique we consider oscillators operating above the microwave band using traveling waves. The Rieke diagram of the oscillator is transformed so that the traveling wave analysis can be performed and a graphical presentation is used to show how arbitrary frequency components of noise are outputted. It is clearly shown how the oscillator output signal (angular frequency ω0) interacts parametrically with the noise equivalent input signal (ω0 ‐ ωn) due to the input signal amplitude dependence of the Rieke diagram, producing a noise output signal of angular frequency ω0. We are also able to show on the Rieke diagram how the noise characteristic varies with the magnitude and frequency of the injection signal.

Mathematical Representation of Microwave Oscillator Characteristics by Use of the Rieke Diagram

This paper shows that the characteristics of oscillators can be phenomenologically expressed by a polynomial function of frequency and amplitude, provided the output signal is nearly sinusoidal, especially at microwave frequency. A method is presented of determining the coefficients of the polynomial from several points on the Rieke diagram, with two examples being shown. The characteristics of oscillators can consequently be represented by several parameters, as in the case of electron tubes and transistors, so that the design of an oscillator circuit may become easier with the aid of an electronic computer.

Analysis of the stability of oscillation modes in parallel‐running oscillators

AbstractThere are several oscillation modes in multiple parallel‐running oscillator circuits. to reduce the adjustment of oscillators and coupling circuits, it is important to obtain single‐mode oscillation in the parallel‐running circuits for power combining so that only the desired mode of oscillation is stable and all the remaining modes are unstable. In this paper, all of the oscillation modes existing in a parallel‐running system consisting of several oscillators with identical Rieke diagrams are extracted and their stability is studied. It is shown that single‐mode oscillation can be easily obtained if the operating point of the desired mode is located at a point away from the origin of the Rieke diagram and the operating points of other modes are at the origin. In this case the operating points of different unwanted modes are necessarily found at points away from the origin and these modes may be stable. However, they are not detrimental in the multiple oscillator system. Analysis and experiment are performed for three representative parallel‐ running systems using hybrid elements.

Mathematical representation of microwave oscillators by use of the rieke diagram

AbstractThe mathematical representation method of treating oscillators was first suggested by van der Pol. Many analyses of oscillators have been conducted employing this method. However, analytical models of oscillators still have some inadequacies. This paper deals with the sinusoidal output wave form of the oscillator and presents the mathematical representation of oscillator properties in a simple but very practical manner. We shall explain how the coefficients in the formulas can be determined from several of the measured points on the Rieke diagram, which is a popular form for the representation of microwave oscillator properties. We shall also give a couple of practical examples.Previously, oscillator properties have been described in graphical form due to the nonlinearity of the device, but they can be described by several numerical values when a mathematical representation is used; with the help of computers, this simplifies considerably the design of oscillator circuits.

Magnetron Rieke Diagram Plotting and Application

A method of plotting magnetron load characteristics utilizing microcomputer is described. With this method, all data for a Rieke diagram is taken in ten minutes and plotted in an hour.

Automatic Rieke Diagram Drawing System (Short Papers)

The development of a system which provides power-constant loci on a Smith chart automatically is presented. The system consists of phase shifters terminated with p-i-n diodes, and a network analyzer.

Low Voltage Magnetron for Consumer Microwave Ovens

AbstractA low cost, low voltage, long life 915 MHz magnetron is described. Utilizing a new type of output coupling, this magnetron provides good efficiency and excellent stability The general magnetron construction is described and the application advantages are discussed. A Rieke Diagram is shown along with a chart showing typical magnetron data. Typical power supplies are shown, where the desired output is obtained without the use of a high voltage transformer.

Rieke diagrams for avalanche diodes show performance as a function of load

Two Rieke diagrams are presented for typical avalanche diodes at 10.859 and 8.217 GHz. Four photographs of the output spectrum are also included to show noise characteristics as a function of load. The noise of the output spectra is greatest where the gradient of the frequency-pulling contours is large and the noise is least where the gradient of the frequency-pulling contours is small.

Crossed-field electron interaction of the distributed-emission space-charge-limited type

A semitheoretical, semiheuristic analysis is given of crossed-field electron interaction of the distributed-emission type. The emphasis of this paper is on the over-all picture of this complex type of interaction, rather than on mathematical exactness. The results are given in terms of five equations from which can be calculated the amount of dc applied power which is converted to real and reactive RF power under given conditions of frequency, RF potential, and magnetic-field strength. These equations are applied to the magnetron oscillator to predict power delivered to the anode by the electron bunches, frequency-pushing characteristics, V-I characteristics, and Rieke Diagrams. The agreement of the experimental data with the calculations over this wide range of characteristics confirms the validity of the analysis.

Automatic Frequency Control of Magnetrons

A practical AFC system for both X-band and Ku-band magnetron radar transmitters has been developed. This system meets the needs of three radar systems currently in production. Frequency stabilization is accomplished by electronically controlling the magnetron load impedance. Therefore, the magnetron ``pulling figure'' is put to use. The closed loop AFC system maintains frequency stability to better than ±2 Mc at Ku-band and ±1.5 Mc at X-band frequencies over wide environmental conditions. The system dynamically compensates for deviations in frequency due to temperature, vibration, shock, changes in duty cycle, drift with life, and poor voltage regulation. The response time of the AFC system is such that, starting at the limits of thle capture range, ``on frequency'' response is Obtained within the first five pulses of the magnetron. One of the radar systems requires a considerable delay between groups of pulses. For this radar, the AFC system provides a memory to hold the conditions for ``on frequency'' response during the delay periods. A qualitative analysis of the closed-loop system is made with reference to the Rieke Diagram. It is shown how a single magnetron has been used to meet two different sets of system performance requirements. System operation and hardware are discussed with reference to practical difficulties.

A Tunable Squirrel-Cage Magnetron-The Donutron

The donutron is an all-metal squirrel-cage magnetron. It is a multisegment magnetron with a single resonant structure. It is tuned by the relative axial displacement of alternate anode segments, through flexure of one wall of the cavity in which the anode structure is supported. During the testing of some sixty models, the operating efficiency and the output power have been increased to 40 to 50 per cent and around 50 watts, respectively (6- to 12-centimeter range). The best model to date tunes over a 1.5 to 1 ratio with power flat to 3 decibels. A single value of voltage and magnetic field is adequate for the entire tuning range. Of the various modes of operation, two are important, a long-wave tunable cavity mode and a shortwave resonant re-entrant-line mode. The former can be entirely suppressed and the latter enhanced by a special phase-reversing anode. In the line mode the highest output powers have been observed. In cold tests, modes around 4 centimeters as well as indication of even shorter resonance wavelengths have been found. A wide range of design parameters has been studied. Rieke diagrams have been taken for the best tubes.