Quasi-optical Open Resonator Research Articles

СУМАТОР ПОТУЖНОСТЕЙ НА БАЗІ КВАЗІОПТИЧНОГО ВІДКРИТОГО РЕЗОНАТОРА ЯК ВИСОКОСТАБИЛЬНИЙ ГЕНЕРАТОР ТЕРАГЕРЦЕВОГО ДІАПАЗОНУ

The efficiency of excitation of the axial-asymmetric vibration TEM10q in a quasioptical open resonator of the power combiner (ORSM) by means of the TE20 waveguide wave is investigated. Based on the theory of mirror antennas, the efficiency of excitation of TEM10q oscillations in a hemispherical resonator using a rectangular waveguide with a cross-section in which the TE20 wave propagates is estimated. Based on the calculations, it was concluded that about 87% of the power supplied to the resonator via the waveguide is used to excite the oscillation under consideration. Therefore, such a resonant system should have good selective properties. Additional studies were conducted to confirm this. It was established that with coordinated excitation of oscillations in the VRSP, the latter has angular and frequency spectrum selection. With the correct selection of the transverse dimensions of a rectangular waveguide with a TE20 wave, located in the center of a VRSP flat mirror, the latter will have a single-frequency response in a wide frequency band and a high power stacking factor in the terahertz range can be provided. When placing the sources in each of the two rectangular waveguides that pass into the emitters of the above dimensions, we will get a power adder based on a hemispherical VRSP. An electrodynamic system of two rectangular waveguides of certain cross-sectional dimensions is proposed and investigated, which allows adjusting the amount of coupling between the sources and the resonator. For this purpose, an E-polarized wire diffraction grating is located on the VRSP flat mirror, changing the period of which regulates the connection of the resonator with the sources. It was found that by choosing the parameters of one-dimensional diffraction gratings (E-polarization) in the openings of the communication elements, it is possible to ensure any predetermined connection of individual sources with a resonant volume. Experimental studies of VRSP at a frequency of 130 GHz were carried out. The measured power at its output was within (10...13 dBm), which corresponds to the efficiency of power assembly k=0.76. The results of the conducted research allow us to draw a conclusion about the prospects of using the developed VRSP in highly stable generators of the terahertz range.

Local Quasioptical Resonator Diagnostics of Semiconductor Wafers

The method of measurement of reflection coefficient behind an orifice in one of reflectors of the quasioptical open resonator is considered. According to the applied mathematical model, the method has the restriction which is consist in use of a short-wave approximation for the orifice size (it dimension is much more than a wavelength). For evaluation of limits of applicability of this method the experimental setup in the threecentimetric range of wavelengths consist of the quasioptical open resonator and the system of positioning of the measuring probe is created. By the experimental study of distribution of fields behind an orifice in the reflector of the open resonator it is found that the method, except restriction of mathematical model, has also restrictions, due to the wave’s interference, reflected from edges of this orifice. It causes a deviation from the uniform amplitude distribution of the field in an opening that can lead to increase in an error of a reflection coefficient measuring. It is also shown that by decrease of the sizes of an orifice formation of a bunch with small divergence, but with significantly more expressed distribution of the field localized about a bunch axis in an aperture is possible. It can be used for diagnostics of inhomogeneity of samples with higher locality.

Small-sized body influence on the quality factor increasing of quasioptical open resonator

The results of an experimental study of electromagnetic waves scattering are described for small electric size bodies in the long-focus open resonator, whose quasioptical approximations are satisfied. It is shown that the effect of the Q factor increase is characteristic for such resonators, and for scatterers, not only spherical, but also of other geometrical forms whose sizes are small in comparison with a wavelength.

ОТКРЫТЫЙ РЕЗОНАТОР ДЛЯ СЛОЖЕНИЯ МОЩНОСТЕЙ В СУБТЕРАГЕРЦЕВОМ И ТЕРАГЕРЦЕВОМ ДИАПАЗОНАХ

ОТКРЫТЫЙ РЕЗОНАТОР ДЛЯ СЛОЖЕНИЯ МОЩНОСТЕЙ В СУБТЕРАГЕРЦЕВОМ И ТЕРАГЕРЦЕВОМ ДИАПАЗОНАХ

ОТКРЫТЫЙ РЕЗОНАТОР С ОТРЕЗКОМ ПРЯМОУГОЛЬНОГО ВОЛНОВОДА

A hemispherical open resonator with a rectangular waveguide section mounted at the center of the open resonator plane mirror is considered. A theoretical analysis has been made to find out that the excitation efficiency of the waveguide wave TE 10 excited by the open resonator oscillation TEM 0 0 q can reach 90 % for some certain cross-sectional dimensions of the waveguide. To this end, a hemispherical open resonator with a superdimensional rectangular waveguide section was experimentally studied in the 4 mm wave region. The cross-sectional dimensions were chosen under the condition of obtaining maximum excitation efficiency of the fundamental waveguide wave. The study shows that the excitation of the fundamental mode alone holds in this resonant system across the whole tuning range. Comparison of reflection coefficients of a waveguide-loaded resonator either with or without a reflecting diffraction grating at the waveguide section bottom indicates that both of the electrodynamic systems have nearly equal losses. Key words: excitation efficiency, open resonator, overmoded rectangular waveguide, diffraction grating Manuscript submitted 29.04.2014 Radio phys. radio astron. 2014, 19(3): 249-257 REFERENCES 1. MIROSHNICHENKO, V. S., SENKEVICH, E. B., PIVOVAROVA, A. G., and YUDINTSEV, D. V., 2010. Excitation of oscillations in a generator of diffraction radiation with multistage space interaction. Izv. vuzov . Radiofizika. vol. 53, no. 3, pp. 200–209 (in Russian). 2. RUSIN, F. S. and BOGOMOLOV, G. D., 1968. Orotron as millimeter-wave generator. 3. SHESTOPALOV, V. P. (ed.), VERTII, A. A., and ERMAK, G. P., 1991. Diffraction radiation oscillators . Kyiv: Naukova Dumka Publ. (in Russian). 4. MYASIN, E. A., EVDOKIMOV, V. V., and IL'IN A. Yu., 2011. Orotron with double periodic structure range 140 ... 300 GHz. Radiotekhnika i Elektronika , vol. 56, no. 4, pp. 454–467 (in Russian). 5. MIROSHNICHENKO, V. S., DUDKA, V. G., YUDINTSEV, D. V., 2010. Shaping of Extended Fields in the Open Resonator with Trapezoidal Mirrors. Radiophysics and Electronics , vol. 15, no. 2. pp. 16–21 (in Russian). 6. SHESTOPALOV, V. P., 1976. Diffraction electronics . Kharkov: Kharkiv University Publishers. 7.KUZ'MICHEV, I. K. and HLOPOV, G. I. 1989. Consistent stimulation Quasi-optical Open Resonator. In: Quasi-optical equipment in the millimeter and submillimeter waves . Kharkiv, Ukraine: IRENASU Publ. pp. 149–156 (in Russian). 8. BURSHTEIN, E. L., 1958. On the power received by the antenna in the fall at her non-planar wave. Radiotekhnika I Elektronika , vol. 3, no. 2, pp. 186–189 (in Russian). 9. KAY, A. F., 1960.Near-field gain of aperture antennas. IEE Trans. Antennas Propag. vol. 8, no. 6, pp. 586–593. DOI: https://doi.org/10.1109/TAP.1960.1144905 10. KUZMICHEV, I. K., 2009. Exitation efficiency of quasioptical resonancesystems. Telecommunications and Radio Engineering. vol. 68, no. 1, pp. 49–63. DOI:10.1615/TelecomRadEng.v68.i1.30 11. KUHN, R., 1967. Microwave antenna. Leningrad. USSR: Sudostroenie Publ. (in Russian). 12. SUHU, R. F., 1963. Non confocal multi-wave resonators for quantum-mechanical oscillator. Proc. IEEE , vol. 51, no.1, pp. 106–111 (in Russian). 13. SHESTOPALOV, V. P., 1985. Physical basis for millimeter- and submillimeter-wave equipmen . Vol. 2 (Sources. Element base. Radio Systems), Kyiv: Naukova dumka Publ. (in Russian). 14. FRAIT, Z. and PATTON, C. E., 1980. Simple analytic method formicrowave cavity Q determination. Rev. Sci. Instrum . vol. 51, no. 8, pp. 1092–1094. DOI: https://doi.org/10.1063/1.1136368 15. VALITOV, R. A. (ed.), DYUBKO, S. P., and KAMYSHAN, V. V., 1969. Technique submillimeter waves . Moskow: Sov. radio Publ. (in Russian). 16. ANDROSOV, V. P. and KUZ'MICHEV, I. K., 1987. The influence of internal irregularities open cavity to communicate with its oscillation waveguide lines . Kharkiv, Ukraine: IRENASU Publ. (in Russian). 17. TARASOV, L, V., 1981. The physics of the processes in generators of coherent optical radiation . Moskow: Rasio i Svyaz' Publ. (in Russian).

Efficiency of excitation of a quasioptical open resonator by a waveguide

We study theoretically and experimentally the efficiency of excitation of an open resonator by a waveguide. A two-dimensional model of a quasioptical two-mirror open resonator, which is excited through a coupling element in the form of an open end of a plane-parallel waveguide, is proposed. The field of the open resonator is represented as the superposition of Gaussian wave beams and its scattering on the coupling element is described by solving the problem of diffraction of waveguide waves and Gaussian wave beams on an open end of a flanged waveguide. Properties of the mirrors and the resonator loss are specified from physical considerations. The calculation results are compared with the experimental data, and a physical interpretation of the obtained results is offered. The factors which influence the efficiency of excitation of an open resonator are identified.

Matching of quasioptical open resonators with waveguide feeders

We consider a semisymmetric open resonator (OR) included in a waveguide feeder, in which the first higher-order mode is excited. We show that a high efficiency of excitation of the mode can be achieved by appropriate choice of coupler dimensions due to the matching of structures of the exciting and operating fields.

Transient response of an open resonator in the time domain

In the present paper a time response of a quasi-optical open resonator when exciting it by a pulse signal with a radiofrequency filling has been investigated using an inverse Fourier transformation. The radiofrequency filling corresponds to millimeter wavelengths region. Fourier image of the time response of the resonator is calculated from a product of two frequency’s functions. One of these functions is the Fourier image of a pulse signal at the resonator input, and the second is a calculated or measured amplitude — phase characteristic of the resonator. When calculating the amplitude- phase characteristic of the resonator (a complex transfer coefficient) a plane — layered model of the resonator was used. Experimental investigation has been conducted in millimeter wavelengths with Fabry-Perot type open resonator. Amplitude- phase characteristic of the resonator were measured in “on passage“ regime in wide frequency band. It was shown that presence of weakly absorbing layer in the resonator leads to changing of the time response of the resonator. The obtained results can be used in the dielectric measurements, defectoscopy of stratiform materials, relaxometry, non-destructive control of materials and structures, etc.

Full-wave analysis of quasi-optical structures

A full-wave moment method implementation, using a combination of spatial and spectral domains, is developed for the analysis of quasi-optical systems. An electric field dyadic Green's function, including resonant and nonresonant terms corresponding to coupling from modal and nonmodal fields, is employed in a Galerkin routine. The dyadic Green's function is derived by separately considering paraxial and nonparaxial fields and is much easier to develop than a mixed, scalar and vector, potential Green's function. The driving point impedance of several antenna elements in a quasi-optical open cavity resonator and a 3/spl times/3 grid in free space are computed and compared with measurements.

Resonance cell of EPR spectrometer for investigation of semimagnetic-semiconductor characteristics

The results of an experimental investigation of a quasi-optical open resonator (OR) with a Hg1−xMnxTe semiconductor are presented. The spectra and field distributions in such a resonator at 130 GHz are shown for three characteristic sample positions in the resonance volume. Recommendations for optimal design of the resonance cell are given. The optimum operating distance between the cavity mirrors is determined to ensure the maximum sensitivity of the EPR spectrometer.

On the extraction of harmonic power from quasi-optical solid-state power combiner

Quasi-Optical solid-state power combiner using high Q open resonator as its resonating system has high stability of frequency and can combine powers from several devices easier than other combiners. In this paper, the technique of harmonic power extraction from quasi-optical open resonator is analyzed and discussed, finally the possibility of this technique is discussed as well.

The new technique of harmonic power combination—Millimeter-wave quasi-optical harmonic power combination

In this paper, the new technique of harmonic power combination—millimeter -wave quasi-optical harmonic power combination is presented. In this technique, by compounding several closed resonators with a quasi-optical open resonator, the harmonic powers of active devices are combined, which takes effectively respective advantages of closed cavity power combination and open cavity power combination and improve the combination efficiency of multiple-device harmonic power combiner. The experimental results for W-band are given and shown this combination method is available.

Electrodynamical Characteristics of Two-Dimensional Open Resonators with Internal Inhomogeneities

ABSTRACT A computing model is constructed describing spectrum and energy characteristics of two-dimensional Open Resonators (OR) that contain various types of inhomo-geneities (dielectric, ideally conducting, resonance, etc.). This model is based on the spectral theory of analytical operator functions in the Hilbert space and on the procedure of quasi-inversion of the operators corresponding to the initial boundary value problems. A number of numerical experiments were carried out, using a computer to study the physical features of spectrum characteristics of inhomogeneous OR, aimed at their implementation in devices of the mm wave range. Wavelengths, geometrical parameters of OR mirrors and their mutual arrangements, and inhomogeneity dimensions were varied in a broad range. In particular, the wave dimensions of the inhomogeneous OR were such that for their analysis the known quasi-optical OR models are inapplicable.

Computer-aided measurement of Q-factor with application to quasi-optical open resonators

A technique for automated measurement of Q based on the observation of resonator response at a set of points near resonance is presented. The resonance curve, suitably corrected for noise and the presence of unwanted modes, is transformed into a linear graph. On the basis of this transformation, an analysis of error in the measurement of Q is carried out. An example of measurement on an open resonator at 97 GHz, with an accuracy of about 1% in the evaluation of Q is included.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Application of multilayer structures at millimeter wavelengths

The paper presents results of theoretical analyses and experimental investigations of the optical characteristics of devices based on multilayer dielectric structures and intended for the millimeter wave band. As is shown, multilayer dielectric structures can prove useful in devices with variable optical characteristics representing coupling elements for quasioptical open resonators, adjustable reflection coefficient mirrors in narrow-band interference Fabry-Perot filters or adjustable multilayer polarizers.

Quasioptical open resonator with dielectric filling

A theoretical and experimental study is performed of the characteristics of a three-mirror open resonator with total internal reflection element realized in the form of a dielectric prism. Expressions are obtained for the amplitude distributions of fields together with the dispersion equation of such a resonator. The solution is carried out in the paraxial wave beam approximation by expanding the beam in a continuous angular spectrum of plane waves. Spectra and field amplitude distributions in the resonator are calculated numerically and studied experimentally. The results of theory and experiment are found to agree well.

Millimeter-Wave Power Combiner Using Quasi-Optical Techniques

A millimeter- or submillimeter-wave combiner using a quasi-optical open resonator to effectively combine the power output of several solid-state oscillators to a single-frequency is described. The combiner makes use of a symmetrical concave spherical resonator with dielectric wedge launchers as energy couplers. To demonstrate feasibility of this concept, experiments were carried out by using two InP Gunn oscillators at 60 GHz, and a combining efficiency of 54 percent has been achieved.

Degenerate oscillations in a quasioptical open resonator with rectangular large-aperture mirrors

The results of this study suggest the following. 1. The spectrum of a precisely fabricated and adjusted open resonator with large-aperture mirrors (2a ≫ λ anda ∼ d) consists of axisymmetric modes when excitation is concentrated along the resonator axis. 2. Alinear combination of modes with rectangular even symmetry corresponds to an axisymmetric mode when the inequality m+n+1=2p+l+1 is satisfied. 3. The degeneracy of modes is effectively removed by insertion of a phase filter into space of the open resonator, or by the use of mirrors with slightly different radii of curvature in mutually orthogonal directions (astigmatic mirrors). 4. Using the well-known method of a test probe for analyzing the spectral content of oscillations in an open resonator [4] requires a certain caution, viz.: it must be remembered that reliable quantitative results will be obtained only for the lowest-order TEM00q mode and for nondegenerate modes with rectangular symmetry. 5. It is expedient to use an open resonator with a “pure” spectrum of natural modes in millimeter-wave devices such as radiospectrometer cells and resonance spaces in diffraction radiation generators, also as active cells in spectrum analyzers of spatial field structures of any configuration.