Lyudmila Mospan

Reflection resonances and natural oscillations of two-aperture iris in rectangular waveguide

The total reflection resonances that take place at the excitation of a two-slot resonant iris in rectangular waveguide are discussed in this paper. Considering the iris as an open-resonator-waveguide structure, the pair of natural oscillations responsible for such resonances was numerically found and investigated. It is pointed out to a parallel between the rejection resonances in two-slot irises and locked-mode resonances in multimode waveguide structures.

Penetration effect in gyrotropic slab: theory and applications

Scattering properties of a homogeneous anisotropic slab are investigated at fixed crystal anisotropy axis orientation. The penetration phenomenon for an incident wave propagating tangentially to the crystal surface is discussed. Slab-based nonreciprocal optical devices are proposed. Their operating principles are based on the slab scattering properties, but not on the Faraday effect. Numerical data for an optical isolator and frequency detector are presented.

Spatial filter with quasi-elliptical response

Spatial filters with quasi-elliptical responses are presented. Proposed designs are based on using the frequency-selective surface with at least two different apertures over the period. Such a surface provides the frequency response with a transmission zero. Just cutting additional aperture over the surface period makes possible such non-trivial feature. Two approaches to design a bandpass filter with quasi elliptical response are presented. In the first case a multiaperture surface is used as a high-quality resonant section, providing the response with the point of the total transmission and with two rejection resonances. In the second case, the grating of perforated strips, is used as a coupling element between half-lambda spatial resonators of an extracted-pole directly coupled filter.

Harmonic rejection filters for the dominant and the higher waveguide modes based on the slotted strips

The simplest notch-type filters to reject the dominant and higher modes in the multimode frequency band are proposed using resonant properties of the iris formed by slotted capacitive strips. Various configurations of the slotted strip iris are considered. The simplest one is a centered capacitive strip in a rectangular waveguide with centered single slot that is able to reject the dominant mode up to the TE30-cutoff. The second one is the double-slot capacitive iris that has the ability to reject at the same frequency both the dominant mode and the TE20-mode. The third configuration is based on two double-slot capacitive strips placed close to the upper and lower walls of the waveguide and provides rejection of the TE10, TE20 and TM11-modes simultaneously. Configurations based on slotted inductive strips to reject TE01 and TM11 modes are also considered. These notch filters are perfectly matched in the operating single-mode range, can be easily fabricated and implemented.

Two‐ and three‐slot irises as bandstop filter sections

The general properties of the single- and double-band rejection sections based on multislot irises have been investigated. A new type of three-section bandstop filter with three-slot irises has been designed and tested.xa0© 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 28: 282–284, 2001.

Polarization Insensitive Bandpass Filter in a Circular Waveguide

A new bandpass circular waveguide filter that provides TE11-mode transmission is presented. The structure is composed by the cascade connection of multi-slot irises. Each multi-slot iris contains a pair of arc-shaped slots and one rectangular slot located between them. Such a filter provides transmitting both linearly polarized TE11-modes at the desired frequency depending on the dimensions of the slots.

Multi-slot iris in circular waveguide

Mathematical approach, allowing calculating the basis of electromagnetic unhomogeneities of arbitrary cross section, is applied to solving the scattering problem for multi-slot iris in circular waveguide. Control of the coupling between the waveguide and the iris via a changing the iris profile is shown. Multi-slot iris with not equal slots forming rejection response is proposed.

Reflection Resonances of Two-Aperture Irises in Rectangular Waveguide

The total reflection resonances that take place at the excitation of a two-slot resonant iris in rectangular waveguide, are discussed. Considering the iris as an open-resonator-waveguide structure, the pair of natural oscillations responsible for such resonances was numerically found and investigated. Some numerical results and experimental data for two-slot irises are presented. It is pointed out to a parallel between rejection resonances in two-slot irises and locked-mode resonances in multimode waveguide structures.

Packet suppression of a leakage of microwave power from industrial heating systems via the higher modes of open waveguide ports

A waveguide bandstop filter intended for an open port of an industrial heating system is numerically modeled. The filter was designed to suppress a leakage of microwave power from a magnetron operating the frequency of 2.45 GHz. A modification the filter providing an improved suppression of a power leaking via higher waveguide modes is proposed. A reduced leakage level is obtained without enlargement of the microwave filter.

Shorted ring aperture frequency selective surface operating at a doubled frequency

Scattering of a plane electromagnetic wave at a frequency selective surface consisting of periodically distributed shorted ring slots in a thin perfect electric conductor is considered. A resonant transmission at the wavelength which is approximately equal to a half of the ring slot circumference is revealed. Electromagnetic coupling by a higher mode of the shorted ring slot makes it possible. Effects of changing the slots dimensions are discussed.