High Order Modes in a Spherical Fabry-Perot Resonator

The accuracy of the approximate solution to the wave equation in the "large aperture" case was investigated. The measured distribution of energy in the various transverse modes corresponded to the Laguerre-Gaussian solutions; resonant frequencies, however, deviated from those predicted by the approximate theory by as much as 2 percent for high radial mode numbers. Two first order perturbation calculations, including a neglected term in the wave equation and the nonsphericity of constant phase surfaces, yielded resonant frequencies in agreement with experiment.     

Modes and Losses of a Four-Mirror Ring Resonator (Letters)

An investigation is reported on modes and losses of a square ring resonator that consists of the numerical solution of the appropriate integral equation for a number of values of the mirrors' aperture and spacing. It turns out that two sets of modes can exist: circulating modes and modes between two facing mirrors. The circulating modes are of the Fabry-Perot type, and their losses can be evaluated on the basis of the losses of suitably equivalent Fabry-Perot resonators.     

Observation and Application of High-Order Azimuthal Modes in a Fabry-Perot Resonator (Short Papers)

High-order azimuthal modes (p = 0, l> 20) were excited at 10 GHz in a Fabry-Perot resonator. The energy of these modes is distributed in a ring around an energy-free central axis, which lends itself to safety applications on rotating machinery and in measuring density profiles of cylindrical plasmas.     

The Coupling of a Single-Ridge Waveguide to a Fabry-Perot Resonator (Short Papers)

The functional forms of the fields in a single-ridge waveguide are presented. Bethe's small-hole diffraction theory is used to determine the coefficient for coupling from various parts of the guide to a Fabry-Perot (FP) resonator. It is shown that frequency-independent coupling over a very broad band is possible, and specific examples are given for the band from 18.0 to 40.0 GHz.     

圆形有源介质F－P腔的横模分析

利用有源增益薄片近似代替有源腔中的增益介质和采用Ｆｏｘ－Ｌｉ迭代法，我们获得了微型ＤＰＬ的圆形有源介质Ｆ－Ｐ腔的模模模型，同时还分析了腔稳态场的振幅和相位分布分别受腔的菲涅耳数Ｎ和非饱和增益增量△Ｇ影响的情况。数值计算结果与文献报道的实验情况比较一致。     

On the Accuracy of the Beam-Wave Theory of the Open Resonator (Letters)

In an interesting paper Erickson has demonstrated how perturbation theory can be used to improve the accuracy of the beam-wave theory of the open resonator. Specifically, two defects of beam-wave theory are considered. The first is that the equiphase surfaces of beam-wave theory are not spherical, the second is that the wave function employed is only an approximate solution to the wave equation.     

Transmission-Line Transformation Between Arbitrary Impedances (Letters)

An analytical method for transforming between two complex impedances using a single transmission-line matching section is described.     

Correction to "Surface Electromagnetic Modes of a Ferrite Slab" (Letters)

In the above paper, (23) is incorrectly referenced. The correct reference should be [4]. A second error appears on page 760 in the second sentence of the paragraph beginning immediately above Fig. 2. In this sentence the words "dynamic" and "magnetostatic" should be interchanged. The authors wish to thank J. Sethares of the Air Force Cambridge Research Laboratories for bringing the latter error to their attention.     

Comments on "Transmission-Line Transformation Between Arbitrary Impedances" (Letters)

The solution given by the author of the above letter, for the characteristic impedance of the line transformer, has been given before (see H. Jasik, Antenna Engineering Handbook, McGraw-Hill, 1961, paragraph 31.3, p. 9). Jasik also gives the correct length of the transformer whereas Milligan and also apparently Day (IEEE Trans. Microwave Theory Tech., vol. MTT-23, p. 772, 1975) give the distance between load and source impedance along the impedance circle, which is not the length of the desired transformer since the transformer should produce at the source the conjugate of the source impedance if matching, which presumably means power matching is desired. Thus in the expression given by Milligan for length, X/sub 2/should be given as -X/sub 2/, which will now agree with Jasik's expression.     

On Optimum Mirrors of the Fabry-Perot Resonator Filled with Anisotropic Medium (Short Papers)

A Fabry-Perot resonator formed by parabolic cylindrical reflecting mirrors and filled with anisotropic medium is analyzed theoretically. For the resonance of the extraordinary wave in such a resonator, optimum shapes of the reflecting mirrors exist, which are derived from the boundary conditions on each mirror.     

Transmission Line Transformation Between Arbitrary Impedances Using the Smith Chart (Letters)

A graphical method for transforming between two complex impedances using a single transmission line matching section is described. The Smith chart is used in a mode where the chart normalizing impedance is arbitrary.     

Correction to "Theory of Periodic Dielectric Waveguides" (Letters)

In the above paper, the information given by (10) on page 125 has been incompletely stated and is therefore misleading.     

Stable and Unstable Spatial Modes in a Resonator with a Half-Disk Shape

Semiconductors - This work was devoted to the study of stable and unstable optical modes in segment shaped resonators. The size of the studied resonators was much larger than the wavelength of the...     

Field Patterns and Resonant Frequencies of High-Order Modes in an Open Resonator (Short Papers)

Using the electromagnetic perturbation theory, it is shown that the linearly polarized TEM/sub pl/ modes (1>0) predicted by conventional methods are not the resonant modes in an open resonator. Instead, two other series of high-order modes are proposed with improved accuracy in resonant frequencies.