Section Of Rectangular Waveguide Research Articles

On-Chip Integration of Orthogonal Subsystems Enabled by Broadband Twist at 220–325 GHz

In this article, we report for the first time on a low-loss compact platform that enables the integration of H-and E-plane rectangular waveguide subsystems enabled by 90 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\circ}$</tex-math> </inline-formula> polarization rotation of rectangular waveguide sections on a silicon-micromachined chip. The proposed platform offers unprecedented design flexibility for a 2.5D fabrication technology such as silicon micromachining, since orthogonal waveguide device sections with full design freedom in H-plane geometries can be cofabricated with sections with full design freedom in E-plane geometries, enabled by novel, integrated waveguide twists optimized for 2.5D fabrication. The platform is developed for use in broadband millimeter-and submillimeter-wave waveguide circuits and prototypes are implemented in the 220–325-GHz band. A prototype chip demonstrating the platform, implemented by bonding three stacked silicon chips, is fabricated. The measured results of the twist prototype exhibit a very low insertion loss of less than 0.2 dB and a return loss of 20 dB or better in most of the 220–325-GHz band. An integrated eighth-degree lowpass waveguide filter with axial ports having a cut-off frequency of 280 GHz is codesigned with the twist transition and fabricated on the platform to demonstrate its application. The filter shows 0.4-dB measured insertion loss and has a measured return loss in the passband of better than 14 dB.

SYSTEMATIZATION OF THE FORMULAS OF THE RESONANT FERRITE ISOLATOR LOSS

Context. The problem is to systematize and improve the models of a resonance ferrite isolator in the rectangular waveguide for the antenna-feeder devices, generating, receiving, measuring microwave equipment containing ferrite decoupling devices: ferrite isolators and circulators. Objective. The goal of the work is to verify the formula for the losses of the resonant ferrite isolator in the direct and reverse directions, as well as the isolator ratio. Method. The research method of the work is a critical analysis of literary sources, which was carried out, but did not bring the desired results, since it did not allow to verify the correctness of the derivation of the formula [17]. Therefore, a number of hypotheses were put forward, what the formula might mean. The difficulty lay in the presence in the formula of the product of trigonometric functions that can be attributed to frequency properties, which was taken as an initial hypothesis, which was not subsequently confirmed. The check included transformation of formulas using mathematical physics in terms of microwave electrodynamics, trigonometry and algebra. The beginning was the formula of the classics [16], similar to the formula of [18], accepted without proof. As it is known, for the main type of wave in a rectangular waveguide, the components of the magnetic field strength, obtained as a solution to the wave equation under the boundary conditions inherent in a rectangular waveguide. One component of the magnetic field strength is along the direction of wave propagation, and the second one is in the transverse direction in the section of the waveguide are proportional to the trigonometric functions cosine and sine with the same arguments. The equality of the two components of the strengths is traditionally uses to find the plane of circular polarization where to place the ferrite isolator, and so the authors use this proportionality to trigonometric functions in their derivation, namely the formulas of trigonometric functions of a double angle, the basic trigonometric identity sine squared plus cosine squared is equal to one for replacing the propagation constants with trigonometric functions, this allows to get rid of radicals in the formulas, these radicals in the formula are due to the phenomenon of dispersion in a rectangular waveguide. The rest of the manipulations with the formula are the reduction of similar terms. Results. There was obtained analytical expressions for the losses of the resonant ferrite isolator in the forward and reverse directions, as well as the isolator ratio by strict mathematical transformations. There was performed such transformations. The ratios of the longitudinal propagation constant to the transverse propagation constant are replaced by the ratios of the trigonometric functions sine and cosine, since they are continuous as opposed to tangents and cotangents. Such a transformation allows to avoid square roots in the formula for the losses of the ferrite isolator in the forward and reverse directions, which are associated with the presence of dispersion in the waveguide, as in the formula for wavelength in the waveguide. The conversion is based on microwave electrodynamics. The formulas are used for the distribution of fields in a rectangular waveguide for the main type of wave. Further transformations consist in taking the common factor out of brackets and other arithmetic transformations. Conclusions. Тhrer was obtained results partially coincide with the well-known [17], the derivation of the formula [17] was obtained for the first time, the studies carried out allowed us to reject the hypothesis that the product of cosines and sines in the loss formula of a ferrite isolator is a frequency characteristic, it appears as a result of arithmetic transformations. To take into account the frequency range, it is used that there is circular polarization at the middle frequency, there will also be circular polarization at the extreme frequency of the range, but the plane of circular polarization will shift in comparison with the position of the plane of circular polarization at the middle frequency. That is, a peculiar system of two equations is obtained with respect to two positions of the polarization plane relative to the wide side of the rectangular waveguide section. The scientific novelty consists in systematization and generalization of the formulas of the loss of the resonance ferrite isolator, the connection between the formulas from different literature sources, both foreign and domestic, is proved, which saves time for researchers of ferrite isolators for the verification of the formula. The practical significance. It may be useful for teaching purposes and in optimization of the ferrite isolator design.

Особливості проєктування поздовжньо-співвісних хвилеводно-мікросмужкових з’єднувачів

The authors justify the use of combined longitudinal-coaxial connectors — waveguide-coaxial or waveguide-microstrip type — in new modern antenna-feeder microwave paths. Using the example of a basic coaxial waveguide-coaxial connector based on a section of a regular rectangular waveguide, the study considers the process of converting an electromagnetic wave of a regular waveguide of the main waveguide type H10 into a transverse electromagnetic wave of a coaxial line with a wave resistance (impedance) Z0 = 50 Ohm. Such a connector allows implementing good electrical parameters — matching (standing wave ratio, SWR) and linear losses — but its design is difficult to configure and cannot be reliably reproduced. However, the basic operation principles of this connector make it possible to use it as a prototype when creating modern coaxial waveguide-coaxial or waveguide-microstrip connectors. One example of such a modern connector is the sealed longitudinal-coaxial waveguide-microstrip connector based on a segment of H-shaped waveguide, shorted by an end wall on one end. Correcting the reactive component of both inductive and capacitive nature will allow achieving the required parameters of the wave impedance of the connector. With this in mind, the author has built an inductive-capacitive system consisting of a matching element in the form of a staggered fin and a corrective element in the form of a rectangular parallelepiped. To ensure the air tightness of the connector design, the segment of the coaxial line was replaced by a sealed coaxial insert, which is a serial electronic component. Particular attention was paid to the layout and design of this sealed waveguide-microstrip connector, as well as to the calculation of the overall dimensions of its elements. The article proposes an original technique for measuring the main parameters of both waveguide-coaxial and waveguide-microstrip connectors. The author forms a mathematical model of combined type connectors based on the scattering wave matrix and presents the parameters of real hermetically sealed longitudinally coaxial waveguide-microstrip connectors based on waveguide segments of various standard sizes and measured at various frequencies.

МЕТАРЕЗОНАТОР ФАБРІ‒ПЕРО, ЯКИЙ ПІДТРИМУЄ РЕЗОНАНСНИЙ РЕЖИМ НА ЗАМКНЕНИХ МОДАХ

Purpose: Investigation of the electrodynamic properties of a Fabry-Perot metaresonator formed by two parallel perfectly conducting, two-dimensionally periodic, two-element screens of finite thickness with rectangular holes. The resonator is excited by a plane linearly polarized electromagnetic wave. The basic cell of each of the screens used as the metaresonator mirrors contains two lengths of rectangular waveguides of different transverse sections. Design/methodology/approach: An operator method for solving the 3D problems of electromagnetic wave diffraction by multielement two-dimensionally periodic structures is used in the study. The computation algorithm uses the partial domain technique and the method of generalized scattering matrices. Findings: As follows from the results of the numerical modeling made, the magnitude of the plane wave reflected from the metaresonator turns to zero at fixed frequencies lying below the cutoff frequencies for the rectangular waveguide sections embedded in the resonator mirrors. The effect of the total electromagnetic wave transmission through the metaresonator at the first lower frequency is characterized by a strong localization of the electromagnetic field in the resonator volume. The reason is excitation of the metaresonator by the exponentially descending field penetrating inside the resonator through the evanescent holes at the resonance frequency. The second low-frequency resonance of the total electromagnetic wave transmission through the metaresonator is associated with the trapped-mode resonance, which is observed in multielement two-dimensionally periodic structures. This case is characterized by a strong localization of the electromagnetic field from both sides near the metaresonator mirror surfaces. Conclusions: The unique electrodynamic properties of the metaresonator can find application in the devices for measuring the electrophysical parameters of composite materials with high losses. The effect of strong localization of the electromagnetic field both in the resonator volume and near the mirror surfaces can be used for monitoring the gaseous substances in crowded places. Key words: two-dimensionally periodic screen; rectangular waveguide; Fabry-Perot metaresonator; reflection factor; evanescent waveguide; trapped-mode resonance

Robust Tolerance Design of Bandpass Filter With Improved Frequency Response for Q-Band Satellite Applications

A rectangular waveguide bandpass filter for <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Q$ </tex-math></inline-formula> -band with simple fabrication is proposed in this letter. The design is based on the use of the first passband replica of commensurate-line stepped-impedance structures and achieves the suppression of their inherent low-pass response. In order to do it, the filter is implemented by rectangular waveguide sections with different widths and heights that can be analytically calculated. The technique is validated by a ninth-order Chebyshev filter with passband between 40 and 43 GHz and fabrication yield equal to 84% for a manufacturing error of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pm 20~\mu \text{m}$ </tex-math></inline-formula> . The measured results of the prototype fabricated with computer numerical control (CNC) milling are in good agreement with the simulated ones.

Effect of Build Orientation and Laser Power on Microwave Loss in Metal Additive Manufactured Components

The adoption of metal additive manufacturing into the production of passive microwave components is still in its relative infancy. However, it is of increasing interest due to the offer of geometrical design freedom and significant weight reduction. The electrical properties of additive manufactured components are still inferior to traditional manufacturing techniques owing to the poor surface finish, especially on overhanging surfaces, which are unavoidable in three-dimensional microwave components. In this paper we present experimental findings on the disparity in microwave surface resistance values between three common build orientations, as well as findings that establish a connection between increasing downskin laser power and a reduction in surface resistance for overhanging surfaces. Finally, additive manufactured rectangular waveguide sections are measured to assess the influence of combined upward and downward facing surfaces on surface resistance.

A multi-function resonator based on an asymmetric tri-post rectangular waveguide section

AbstractA novel waveguide resonator is proposed in the paper. The resonator is composed of three rectangular partial-height posts inserted along a rectangular waveguide cross-section. A pair of lateral posts is mounted symmetrically whereas the third antipodal post is centered. The resonator enables bandreject, singlet-type, and pseudoelliptic responses. The operating regimes are achieved by a manipulation with the pair of lateral posts, namely by changing their heights or their locations in a waveguide cross-section. A filtering function is realized as the third mode is exploited as the resonant one. Measurement data are presented for WR90 waveguide. An explanation of the resonant phenomena in post-based sections in terms of eigen regimes and interacting oscillations is proposed.

Multiphysics and Multipactor Analyses of TE022-Mode High-Power X-Band RF Window

This letter presents the design of an overmoded $X$ -band RF window for use in high-power microwave tubes, such as klystron, magnetron, and linear accelerator (LINAC). The cylindrical section of the window containing dielectric barrier operates in the TE022 mode. Conversion from TE10 mode to TE022 mode is achieved using four rectangular slots made on the narrow walls of the rectangular waveguide sections. The simulation results for the proposed design in CST and HFSS are in good agreement. The return loss, insertion loss, and bandwidth are obtained as 52.76 dB, 0.06 dB, and 41.4 MHz, respectively, at 9.3 GHz. Coupled electromagnetic, thermal, and structural simulations are performed to study the multiphysics performance of the RF window. The multipactor analysis is carried out in SPARK3D to determine the multipactor threshold. The proposed TE022 mode RF window can operate safely at a 20.75 MW of peak power.

A Continuous Beam Steering Slotted Waveguide Antenna Using Rotating Dielectric Slabs

The design, simulation, and measurement of a beam steerable slotted waveguide antenna operating in X band are presented. The proposed antenna consists of a standard rectangular waveguide (RWG) section with longitudinal slots in the broad wall. The beam steering in this configuration is achieved by rotating two dielectric slabs inside the waveguide and consequently changing the phase of the slots excitations. In order to confirm the usefulness of this concept, a nonresonant 20-slot waveguide array antenna with an element spacing of $d = 0.6\lambda _{0}$ has been designed, built, and measured. A 14° beam scanning from near broadside ( $\theta = 4^{\circ }$ ) toward end-fire ( $\theta = 18^{\circ }$ ) direction is observed. The gain varies from 18.33 to 19.11 dBi and the antenna efficiency from 95% to 79%. The sidelobe level is −14 dB at the design frequency of 9.35 GHz. The simulated and measured co-polarized realized gains are in good agreement.

Contactless Linear Rotary Joint at Ku-Band

Our laboratory has developed a drone detection radar that involves a mechanical scanning antenna. Radar and antenna systems that have mechanical scanning require an additional component called a rotary joint (RJ). The purpose of RJ in scanning assemblies is to provide an uninterrupted link between the antenna and the transceiver. In our system, antenna and transceiver are linearly polarized and use TE10 mode along the rectangular waveguide section. TE10 modes are asymmetric in nature making them incompatible with the rotating motion of the antenna. An RJ is presented with back-to-back mode transitions using symmetric modes along the circular waveguide and contactless branch line joint. The mode used along the circular waveguide for symmetry purpose is TM01. An I-type linear RJ topology is selected due to lack of space along the lateral directions and system configuration. The problem of antenna matching while scanning was solved at 14.0–14.5 GHz at Ku -band using single-channel linear RJ.

Circuit Modeling of 3-D Cells to Design Versatile Full-Metal Polarizers

An original mechanism is here proposed to achieve polarization conversion from linear to circular with the use of full-metal polarizing screens. Such screens are self-supported and conceived from the periodic arrangement of 3-D unit cells. They are built from sections of rectangular waveguides operating below the cutoff frequency and loaded with slotted discontinuities. The polarizer operates in transmission mode; the discontinuities are responsible for both its high return losses and the conversion of the impinging linear polarization to circular. Two types of 3-D cells are presented, and both of them are analyzed and designed through equivalent circuit models (CMs). These models have been thoroughly built in order to capture all the phenomena underlying the discontinuities’ behavior. The characterization of the first cell is fully done analytically, whereas the second cell needs reduced help from a full-wave solver. Furthermore, the CMs allow simple design guidelines to be identified for this type of polarizer. Two designs are performed operating in Ka-band, proving that an extension of the operation bandwidth (axial ratio and $S_{11}$ ) to 11% is possible by employing the second cell.

Design and simulation of output mode conversion structure of relativistic magnetron with all cavity output

A relativistic magnetron using all cavity extraction and semi-transparent cathode has the virtues of compactness, high output power and high efficiency. The three-dimensional particle-in-cell simulations show that 1.15 GW output microwave with an efficiency about 50% can be obtained at S-band with pure TE11 mode of the fan waveguide. However, due to the fact that the output structure is composed of three detached fan waveguides, mode conversion structure in the output region is required for the convenience of practical applications. Therefore, two mode conversion structures are studied for the output mode conversion. The first structure is to widen gradually or abruptly the fan waveguide in the azimuthal direction from a given position (starting point) along the microwave transport direction. And then the three fan waveguides are connected into one coaxial waveguide. The effects of the position of the starting point on the beam-wave interaction and microwave extraction are numerically studied. For the convenience of description, we define L as the axial distance between the center of the output coupling hole and starting point. Simulation results show that for the abrupt and gradual variation case, when the length of L changes in a relatively wide region, the output power is larger than 1.0 GW in TEM mode at S-band. It is about 90% of the conventional fan waveguide with 1.15 GW. For the gradual variation case, the optimal value of L equals 10.0 cm, and the corresponding output power is beyond 1.0 GW. For the abrupt variation case, the optimal value of L equals 13.75 cm, the corresponding output power is about 1.15 GW. But in the abrupt variation case, the output power is a little more sensitive to the value of L. The second structure is to convert the fan waveguide into a rectangular waveguide. Ａcompound waveguide composed of a section of fan waveguide and a section of rectangular waveguide is designed for studying its feasibility. In the compound waveguide, the wide edges of the cross section of the rectangular waveguide are tangent to the inner and outer arc of the fan cross section respectively. And the narrow edges cross the end points of the outer arc. Simulation results show that in the compound waveguide the microwave with TE11 mode of the fan waveguide input at the inlet can be changed into the TE10 mode of the rectangular waveguide at the outlet with almost no power loss. In all, the output microwave power larger than 1.0 GW could be obtained after using the two proposed mode conversion structures. In practical applications, one could choose the relevant mode conversion structure according to the requirement.

Reflection Measurement of Low-Reflective Loads at Millimeter Waves

The well-known cross-ratio method of correction of the complex reflection coefficient of low-reflective waveguide one-port devices, which is well established up to 110 GHz, is extended to millimeter wave frequencies where the impedance standard, a quarter-wavelength rectangular waveguide section at midband, may become too thin to be fabricated and handled. Therefore, an alternative extended cross-ratio correction method (ECM) is presented where a pair of longer waveguide sections having well-defined cross-sectional dimensions and lengths is used instead. Their difference in length is a quarter-wavelength at midband. The method is tested in the WR-5 waveguide band (frequency $f = 140$ –220 GHz), where a quarter-wave line is still thick enough to handle. The measurement results obtained by the ECM using two lines agree well with the results from the single-line cross-ratio method as well as with measurements obtained from a line-reflect-line calibration. Sensitivity coefficients are derived, which indicate how the measuring result is influenced by deviations of the different input parameters that are necessary to calculate the reflection coefficient.

Резонансы отражения в прямоугольной волноводной секции с парой встречных прямоугольных штырей

Резонансы отражения в прямоугольной волноводной секции с парой встречных прямоугольных штырей

Influence of rectangular and periodic rectangular profiles in the cross section of the straight waveguide on the output field

The first and the main objective of this research is to understand the influence of the rectangular and periodic rectangular profiles in the cross section along the straight waveguide on the output field. The second objective is to develop the technique to calculate the rectangular and periodic rectangular profiles in the cross section. The contribution of the technique and the particular application are important to improve the method that based on Laplace and Fourier transforms and the inverse Laplace and Fourier transforms also for the discontinuous rectangular and periodic rectangular profiles in the cross section (and not only for the continuous profiles). All the graphical results will be demonstrated as a response to a half-sine () input-wave profile and the rectangular and periodic rectangular profiles in the cross section of the straight rectangular waveguide. The application is useful for straight waveguides in the microwave and the millimeter-wave regimes, with rectangular and periodic rectangular profiles in the cross section.

Theoretical and Experimental Investigation on the Probe Design of a Ridge-loaded Slot Type for Near-Field Scanning Microwave Microscope

In this paper, a rectangular waveguide probe with a ridge-loaded straight slot (RLSS) is presented for a near-field scanning microwave microscope (NSMM). The RLSS is located laterally at the end wall of the cavity and is loaded on double ridges in a narrow straight slot to improve the spatial resolution compared with a straight slot. The probe consists of a rectangular cavity with an RLSS and a feed section of a WR-90 rectangular waveguide. When the proposed NSMM is located at distance of 0.1mm in front of a substrate without patches or strips, the simulated full width at half maximum (FWHM) of the probe improve by approximately 31.5 % compared with that of a straight slot without ridges. One dimensional scanning of the E-plane on a sample under test was conducted, and the reflection coefficient of the near-field scanning probe is presented.

Anomalous Dispersion Characteristics of Periodic Substrate Integrated Waveguides From Microwave to Terahertz

This paper presents the anomalous dispersion characteristic of a periodic substrate integrated waveguide (SIW) with results obtained by a rigorous formulation using the hybrid generalized scattering matrix (GSM) and finite-element method (FEM), showing two types of anomalous modal behaviors, namely: 1) ${\rm TM}_{0}$ surface wave leakage in connection to the near cutoff transverse resonance of a rectangular waveguide section alternating with either microstrip or parallel sections and 2) complex modes inside the lowest ${\rm TE}_{01}$ -like propagating zone. A rigorous limiting case study of the SIW via spacing approaching less than 10% of via diameter validated the proposed hybrid GSM/FEM formulation and enabled the detailed description of various types of modes, namely, propagating ${\rm TE}_{01}$ -like, a pair of complex modes, and above the stopband regimes, respectively. Convergence analysis and comparisons to the existing literature were carried out to validate the proposed method in addition to the limiting case study. Measured results of the CMOS prototypes validate the theoretical prediction from 325 to 450 GHz and confirm the accuracy of the proposed method.

Components of the radio-frequency system for traveling-wave deflecting structures

Components of a radio-frequency system for deflecting structures of the S-frequency range, which are included in the electron-beam diagnostic complexes for a free-electron laser (XFEL, Germany), were designed. Waveguide-coaxial and waveguide-strip directional couplers, a waveguide absorbing load, a waveguide window, and an E-bend were developed. A connecting element between two deflecting structures in the form of a U-shaped rectangular-waveguide section was also calculated.

СПЕКТРАЛЬНЫЙ ПОДХОД К ОЦЕНКЕ РЕЗОНАНСОВ ОТРАЖЕНИЯ В ПРЯМОУГОЛЬНОЙ ВОЛНОВОДНОЙ СЕКЦИИ С ПРЯМОУГОЛЬНЫМ ШТЫРЕМ

Revealing the physical phenomena causing various resonant phenomena is a key to successful design of frequency selective structures. Within the frames of the spectral theory of open waveguide resonators, the nature of the total reflection resonance formed by a rectangular waveguide section with a rectangular post inside is studied. The waveguide section is considered as a single-channel multimode resonator. An interpretation of the total reflection resonance is suggested as a result of excitation of natural oscillations in the resonator. Transformation phenomenon for the resonant mode explaining the resonant reflection of the incident wave by symmetric structures is revealed. It is established that the resonant frequency and quality-factor are estimated precisely by the complex frequency of a single natural oscillation. It is shown that quantitative estimations for the reflection resonance obtained within the spectral theory of open waveguide resonators are in order of magnitude more precise than those obtained within the classical approach. The results obtained make synthesis of bandstop filters, possessing complicated frequency behavior, to be more efficient. Key words: resonance of reflection, rectangular waveguide, natural vibration Manuscript submitted 06.05.2014 Radio phys. radio astron. 2014, 19(3): 258-266 REFERENCES 1. ROSENBERG, U. and AMARI, S., 2007. A novel band-reject element for pseudoelliptic bandstop filters. IEEE Trans. Microwave Theory Tech . vol. 55, no. 4, pp. 742–746. DOI: https://doi.org/10.1109/TMTT.2007.893653 2. KIRILENKO, A. A., KULIK, D. Yu, MOSPAN, L. P., and RUD', L. A., 2013. Reflection Resonances in a Waveguide Section with Two Different Height Posts. Radiophysics and Electronics , vol. 13, no. 2, pp. 154–158 (in Russian). 3. POLITI, M. and FOSSATI, A., 2010. Direct coupled waveguide filters with generalized Chebyshev response by resonating coupling structures. In: Proc. of European Microwave Conference . Roma, Itali. pp. 966–969. 4. TOMASSONI, C. and SORRENTINO, R., 2013. A new class of pseudoelliptic waveguide filters using dual-post resonators. IEEE Trans. Microwave Theory Tech . vol. 61, no. 6, pp. 2332–2339. DOI: https://doi.org/10.1109/TMTT.2013.2258171 5. SHESTOPALOV, V. and SHESTOPALOV, Yu., 1996. Spectral Theory and Excitation of Open Structures . London: Peter Peregrinus Publ. DOI: https://doi.org/10.1049/PBEW042E 6. RUD', L. A., SIRENKO, YUu. K., YATSIK, V. V., and YASHINA, N. P., 1988. A Spectral method of analyzing the effects of total wave transformation by open-periodic and waveguide resonators. Radiophys. Quantum Electron . vol. 31, no. 10, pp. 894–899.DOI: https://doi.org/10.1109/TMTT.2013.2258171 7. KIRILENKO, A.. A., YASHINA, N. P., 1980.On the relationship between resonances in the "locked" modes with the excitation modes of quasi non-closed volume. Pis'ma v ZHTF , vol. 6, no. 12, pp. 1512–1515. 8. KIRILENKO, A. A. and TYSIK, B. G., 1993. Connection of S-matrixof wave guide and periodical structures with complex frequency spectrum. Electromagnetics . vol. 13, no. 3,pp. 301–318. DOI: https://doi.org/10.1080/02726349308908352 9. PRIKOLOTIN, S. A., STESHENKO, S. A., KULIK, D. YU., RUD, L. A., and KIRILENKO, A. A., 2012. Fast full 3D EM CAD of wave guideunits based on the generalized mode-matching technique. In: Proc of Int. Conf. on MMET . Kharkov, Ukraine. pp. 109–112. 10. MOSPAN, L. P., PRIKOLOTIN, S. A., STESHENKO, S. A., and KIRILENKO, A. A., 2013. Spectral Properties of a Rectangular Waveguide Section with Two Uneven Rectangular Posts. Radio Phys. Radio Astron . vol. 18, no. 4, pp. 349–356 (in Russian).

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).