IEEE Transactions on Microwave Theory and Techniques

The problem of electromagnetic wave propagation in a rectangular waveguide containing anisotropic slabs was considered by several authors. Their treatments, however, only cover particular cases (lossless media, TEm0 modes); they do not provide all the information required for the design of microwave devices such as ferrite isolators, which are still developed by empirical methods. The t... View full abstract»

Two pulse amplitude modulation (PAM) methods by a high-efficiency frequency multiplier with varactor diodes are compared. Typical results achieved for an X-band to Q-band tripler prove that the direct PAM is better than the indirect one under the same conditions. The former acts as a pulse shaper (PS), and has an output rise time smaller than the rise time of the output voltage of the modulator ch... View full abstract»

For propagation in lossless waveguide, the rigorous impulse response function is given. It is shown that its instantaneous frequency is that which has reached the output at that time by propagating at the group velocity. For a square envelope pulse with a carrier frequency ω above the cutoff frequency ωc, the propagation of the envelope and of the phase are essentially descr... View full abstract»

The theory of modal expansions in an ideal cavity, in the presence of low-frequency current and charge distributions, is developed using the scalar and dyadic Green's functions. The case of a vertical antenna in a rectangular cavity is solved in detail, and the need for irrotational as well as solenoidal eigenvectors in the solution is established. The solutions are obtained in double-sum form, ac... View full abstract»

The distraction of a plane light wave incident obliquely upon an isotropic dielectric layer traversed Iongitudinally by an acoustic microwave is examined by means of a guided-wave approach. In addition to a considerable amount of physical insight, this approach provides a wide range of techniques that have already been developed extensively in the area of electromagnetic microwaves. As a consequen... View full abstract»

To provide a programmer-defined function for Bessel functions of all four kinds (J, Y, I, and K) covering the range of orders and arguments useful in microwave work, with emphasis on user convenience. View full abstract»

The possibility that a radially nonuniform dielectric might enhance the propagation characteristics of a surface wave line is discussed in terms of the axial cylindrical surface wave on a cylindrical structure. Attention is given to the field structure in the dielectric to determine the effect of the nonuniformity on the dielectric loss. Conclusions are deferred, however, until the change in surfa... View full abstract»

An approximate technique for eigenvalue equations, the variation-iteration method, is commonly used in theoretical physics. Through an adequate numerical treatment it reduces to the inverse iteration method. It is shown here that this technique is most promising. Starting from an initial trial function, iterates are calculated, in which the components relative to the unwanted true eigenfunctions a... View full abstract»

A criterion is presented for establishing the required degree of isolation between injection-locked microwave oscillators to prevent reverse Iocking. In particular, the effect of circulator directivity and oscillator harmonics on the performance of the locking circuit is discussed. The injection-locked performance of pulsed and CW transferred electron oscillators is used as an example. View full abstract»

The radiation characteristics of 360° circumferential slots in rigid dielectric-coated coaxial cable are studied both theoretically and experimentally. The ultimate aim of this work is to use an array of such slots to launch a surface wave on the Goubau line formed by the outer conductor of the coaxial cable and the concentric dielectric coating. The possible advantage of this method over that... View full abstract»

A finite-difference Green's function method for solving time-harmonic wave guide scattering problems involving metallic obstacles of finite size by computer is described. The method is applied to the two-dimensional problem of a TE10 mode impinging on cylindrical metallic posts of arbitrary shape in a rectangular waveguide. The equivalent susceptance of a transverse semidiaphragm comput... View full abstract»

Theory and experimental results are presented to show the possibility of using a resonant post technique for characterizing dielectric and magnetic materials at microwave frequencies. Results of the temperature dependence of the relative dielectric constant of nonmagnetic materials with εr, varying from 4 to 60 are presented and also loss tangent measurements at room temperature... View full abstract»

An open-type X-band resonator was constructed of two cylindrical reflectors with crossed axes, separated by half the radius of curvature. The diffraction loss of this structure was found to be several orders of magnitude less than when the axes of the cylinders were made parallel, while the otherwise equivalent flat-flat resonator had the highest loss of all. A formula for the resonant frequencies... View full abstract»

This correspondence describes a perturbation technique for obtaining the spinwave linewidth of polycrystalline garnet spheres with large values of ΔHk. Conventions waveguide cavity techniques require power levels in the kilowatt region to excite the parallel-pump instability. By using a dielectric resonator, large RF magnetic field intensities can be generated using relatively low... View full abstract»

A simple formula is derived for calculating the amplitude of the field that is due to an elemental radiator which radiates into a particular waveguide mode. The method used is based on rather elementary principles, and appeals readily to physical intuition. In this technique, the field radiated into an infinite-length waveguide is obtained from the expression for the field developed by the radiato... View full abstract»

A device is described which performs the operation of correlation at microwave frequencies (L-band). Signal delay is provided by two transmission mode yttrium-iron-garnet delay lines magnetically biased for magnetoelastic wave propagation. Variation of delay is effected by electronically changing the magnetic bias on each delay line. Because group and phase delay are different functions of applied... View full abstract»