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In this paper, we present the compact bandpass cavity filters for UHF range. We investigate the properties of coaxial resonators with various numbers of tubular posts from one to four. We show that...

Cylindrical waveguiding structures with complex transverse cross sections and application of the structures in modern information and communication systems are reviewed. History of and prospects for development of such microwave elements are considered, and methods for electrodynamic analysis are analyzed. Applications of complex cylindrical waveguide and coaxial structures as basic elements in the systems for generation of signals, radio communications, radars, and sounding are presented.

—The problem of determining the complex dielectric constant of materials in the centimeter and millimeter wavelength ranges is solved using the waveguide method with an double-ridged waveguide. The use of a segment of an double-ridged waveguide as the measuring cell made it possible to expand the operating frequency range and increase the measurement accuracy due to localization of the electromagnetic field energy in the space between metal ridges. The electromagnetic fields of hybrid types of waves in the double-ridged waveguide were calculated by the partial region method taking into account the peculiarities of the electromagnetic field on the metal and dielectric ridges. The results of measuring the complex dielectric constant for samples made of ebonite, Teflon, and fiberglass are presented.

We present a new type of waveguide bandpass quasi-elliptic filter whose resonators are implemented by thin transverse resonant diaphragms with an aperture in the form of a rectangular windo...

We have synthesized elliptic bandpass waveguide filters. The resonators of the filter are thin plane-transverse resonant irises with an aperture in the form of a rectangular window with two metal L-shaped ridges. The electrodynamic problem of calculating the complex conductance of the iris is solved. An equivalent circuit of the resonant iris is proposed, and the correspondence of the geometric size of its aperture to the parameters of the circuit is established. The results of synthesis of an elliptic filter for the WR137 rectangular waveguide with a passband of 6.35–6.83 GHz at a level of −3 dB are presented. The longitudinal size of the filter is 34 mm, which ensures the small size of the developed device.

Computer simulation and synthesis of waveguide selective devices based on circular waveguides with T-shaped metal ridges have been performed. A method for obtaining the initial approximation for further optimization of their characteristics has been described. As basic elements, cavity resonators consisting of sections of circular waveguides with two T-shaped metal ridges are used. The results of simulation of a band-pass filter have been presented.

We solve the problem of electrodynamic analysis of the mode composition of radiation in a circular waveguide with thin radial metal ribs. Algorithms for calculation of cutoff wave numbers and components of the electromagnetic fields of the H and E modes have been developed with allowance for the singularity of the field behavior near a thin metal rib. Spectral characteristics of the waveguide are studied. Structures of the electromagnetic fields of the fundamental mode and the higher modes are determined.

A novel approach to computer simulator development of microwave measurement equipment is presented. The main feature of the software is an interface of the simulator, which is an interactive image of the real equipment allowing to manipulate the keys and other elements of the front panel by the computer mouse. For the measurement procedure, the simulator allows to use analytical formulas or upload the data from the computer models of the microwave devices and from the real measurements in *.s2p format. Implementation of the developed simulator into the educational process provides each student with an unlimited access to the measuring equipment and gives the opportunity not only to study the characteristics of microwave devices but also to gain experience with the real equipment due to interactive computer interface that is completely identical to real front panel.

We consider an algorithm of calculating the characteristics of the fields of hybrid modes in waveguides with complicated cross sections. The presented algorithm makes it possible to allow for the specific features of the behavior of the electromagnetic-field components near the dielectric and metal ribs of the waveguide. The results of calculating the electrodynamic characteristics of the hybrid HE and EH modes in a Π-shaped waveguide with layered and piecewise-layered dielectric filling are reported. The tables of cutoff wave numbers are presented, and the structures of electromagnetic fields of hybrid modes are shown. The results obtained by using the method proposed and the numerical methods are compared.

The article considers the algorithm for calculating characteristics of fields of hybrid types of waves in waveguides with complex cross sections. The presented algorithm takes into account the sing...

Results of the electromagnetic analysis of single pin resonant elements in ridge rectangular waveguides are presented. The equivalence of scattering characteristics of pin elements and thin flat transverse diaphragms is shown. Electromagnetic fields and cutoff wave numbers of ridge waveguides are determined by the partial domain method taking into account the field singularity at the edge. Results of the synthesis of a three-resonator band-stop filter with a stopband of 7.5% and a passband reflection level of no more than–20 dB in the entire waveguide operation band are presented.

We solve the problem of electrodynamic analysis of a complex waveguide resonance diaphragm with an aperture in the form of a rectangular window with two centrally symmetric L-shaped ridges. The properties of the diaphragm are studied on the basis of the analysis of the imaginary part of its normalized conductivity. Critical wave numbers and electromagnetic fields are calculated by the partial region technique allowing for the singularity of the electromagnetic field on metal ribs. It is shown that the imaginary part of the normalized conductivity of the diaphragm as a function of the frequency not only turns to zero, but also contains a discontinuity of the second kind, which corresponds to the parallel and series resonance.

The problem of electrodynamic analysis and synthesis of band-pass microwave filter based on L-ridged rectangular waveguide is solved. The possibilities of multilevel substrate integrated waveguide (SIW) filter structure implementation for ridged rectangular waveguides are discussed. The compact SIW filter with 4% pass-band and a stop-band attenuation level −60 dB is described.

We solve the problem of electrodynamic analysis and synthesis of bandpass filters based on rectangular waveguides with complex L-shaped ridges. Cutoff wave numbers and components of the electromagnetic field were calculated by the partial region method with allowance for the singularity of the electromagnetic field on metal ribs. As a prototype, the model of a cutoff filter and an approximation of its amplitude-frequency characteristic by the Chebyshev polynomials were used. Examples of synthesis of narrow-band filters with inputs based on a rectangular waveguide and an H-waveguide are presented. Advantages of using a novel waveguide with a complex cross section in the filter are considered, including the appearance of a total reflection frequency (antiresonance) in the filter rejection band, which allows one to significantly extend this band and increase the attenuation level in it.

A technique of electrodynamic analysis and synthesis of directional couplers based on Π-shaaped waveguides with a system of small coupling apertures is reported. Parameters of coupling between two waveguides through a small aperture are calculated within quasi-static Bethe’s theory. Critical wavenumbers and components of the electromagnetic fields of ridged waveguides are calculated with allowance for the features of the electromagnetic field on the edge. The characteristics of synthesized directional couplers based on Π-shaped waveguides with coupling along the wide wall of 20 and 10 dB are reported.

A technique of electrodynamic calculation and computer-aided simulation of the structure of the electromagnetic fields of TE and TM waves in a rectangular waveguide with two L-shaped ridges and a lossless air filling is presented. The problem is solved by means of the partial domain method with allowance for the edge singularity of the electromagnetic field. Cutoff wave numbers, the structure of the electromagnetic fields of various TE — and TM-wave modes in the cutoff regime, the characteristic impedance, and the breakdown power for the fundamental waveguide mode are calculated.

Computer simulation of a typical small-sized pilotless vehicle is carried out. Three-dimensional diagrams of the secondary radiation (scattering diagrams) of the vehicles are derived. Frequency dependences of the secondary radiation in the range 50 MHz–4 GHz are plotted. The possibilities of the object model simplification are discussed. The polarization features of object detection are studied. The possibility of object recognition against the bird’s background is evaluated.

Problems of analysis and synthesis of microwave selective devices are solved in the case when such devices are the bandpass filters based on thin plane transverse metal diaphragms in ridge waveguides. The vector eigenfunctions and cutoff wave numbers of waveguides are calculated with the help of the partial-domain method taking into account the edge singularity of the electromagnetic field. The multimode scattering matrices of a cascade connection of reentrant resonators are calculated with allowance for the interaction of irregularities via higher modes of evanescent H and E waves in a waveguide. The amplitude-frequency and phase characteristics and the dimensions of synthesized bandpass filters are presented for the case of Π and H-waveguides.

An algorithm is developed for calculation and optimization of mode transformers based on bends of rectangular ridge waveguides. Cutoff wave numbers and components of electromagnetic fields are calculated with the use of the partial-domain method with allowance for the edge singularity of the electromagnetic field. The amplitude coefficients of the modes propagating in a deformed waveguide are calculated with the help of the cross-section method. The geometries and characteristics of H-waveguide transformers are presented.