Vladimir A. Labay

Ridge waveguide polarizer with finite and stepped-thickness septum

This contribution presents new design dimensions for the ridge waveguide septum polarizer. Emphasis is placed first, on including the finite septum thickness in the analysis; second, demonstrating its influence on the polarizer performance; third, including a stepped approach for extremely thick septa; fourth, optimizing components without the need for additional phase-adjusting structures; and fifth, providing the application engineer with some design guidelines. Examples for varying septum thickness and/or number of sections are given for C-, X-, R120-, Ku- and K-band applications. The analysis is based on an efficient mode-matching technique. Evolution-strategy methods are used for optimization. Both algorithms are translated into PC-operational software. Results are compared with previously published theoretical/experimental polarizer data and with a finite-element analysis, and are found to be in good agreement. >

Matrix singular value decomposition for pole-free solutions of homogeneous matrix equations as applied to numerical modeling methods

A general technique for solving homogeneous matrix equations as applied to numerical modeling procedures in microwave and millimeter-wave structures is introduced. By using singular value decomposition, well-known numerical problems related to poles and steep gradients in the determinant function are eliminated. The proposed technique is generally applicable, improves the accuracy and reliability of computed results, and significantly reduces the CPU time due to a more moderate behavior of the function to be analyzed. A dispersion characteristics example of a conductor-backed slotline MMIC structure illustrates the advantage of the pole-free formulation over conventional determinant calculations.<<ETX>>

E-plane directional couplers in substrate-integrated waveguide technology

In order to analyze and design components in substrate-integrated waveguide technology, it is important that the transitions to interface ports do not significantly influence the components performance. In this paper, it is demonstrated that the commonly used microstrip-to-SIW transitions are not sufficient to evaluate a SIW structure within a SIW environment. Therefore, we present all-dielectric rectangular waveguide interface ports that considerably reduce the reflections at the transition to the SIW component. These new ports are then applied to the design of SIW E-plane couplers, both with standard dual-circular apertures and as Riblet-Saad couplers. It is demonstrated that SIW couplers with return loss and isolation of much better than 20 dB can be designed. Several 10 db and 3 dB couplers covering the entire Ka-band frequency range are presented. The basic design procedure is validated by comparison with measurements and computations available in the common literature.

Design of dual-band substrate-integrated waveguide E-plane directional couplers

Dual-band substrate-integrated waveguide (SIW) couplers for operation in the 20/30 GHz bands are presented. Initial design guidelines follow substrate selection and aperture coupling theory as known from standard air-filled waveguide components. The results demonstrate that this design approach is sufficient for many applications. All-dielectric waveguide ports as well as microstrip ports are used as interfaces to the SIW couplers. Designs are analyzed within an Ansoft HFSS environment, and the approach is verified by comparison with results obtained from CST Microwave Studio. Performances of several prototype designs are presented for dual-band coupling values between 6 dB and 20 dB. All coupler dimensions are specified.

GENERALIZED MODAL SCATTERING MATRIX OF DISCONTINUITY-DISTORTED WAVEGUIDE MULTIPORT JUNCTIONS

A generalized modal scattering matrix formulation is presented for the calculation of discontinuity-distorted waveguide multiport junctions. Unlike common approaches based on three-plane mode-matching techniques, and modifications thereof, which calculate only the fundamental-mode scattering matrix, this algorithm computes the generalized modal scattering matrix of the junction. Therefore, the method allows the computation of components in which other structures are connected as closely as possible to the discontinuity-distorted junction as follows directly from the rigorous incorporation of all higher-order mode interactions. The method is demonstrated at three selected examples: the waveguide corner, the T-junction power divider and the orthomode transducer. Comparison with results obtained by other numerical techniques or measurements available from the literature are found to be in good agreement.

Radio channel characteristics in an indoor corridor environment at 60 GHz for wireless networks

For the next generation wireless local area networks (WLANs) and wireless personal area networks (WPANs), 60 GHz radio channel propagation characteristics in typical indoor corridor environments are addressed in this paper using Matlab simulations of Ray-tracing, ITU-R model and full-3D Ray-tracing model of Wireless Insite. Values of the path gain (PG), rms delay spread (DS) and power delay profile (PDP) for omnidirectional and horn antennas are presented.

A new evanescent-mode filter for densely packaged waveguide applications

A novel evanescent-mode filter structure based on T-septum waveguide technology is presented for applications in extremely compact designs. The excellent characteristics of the T-septum waveguide are utilized to significantly reduce the resonator cutoff frequency compared with standard ridge waveguide designs. This allows the evanescent-mode guide to have a smaller cross-section, hence considerably reducing the overall length of the filter. The computer-aided design uses a full-wave mode-matching technique which takes into account higher-order mode coupling at all discontinuities involved. Design data are given for X- and Ka-bands. The method was verified by measurements. The manufactured 10-GHz prototype measured only 18.4 mm in length.<<ETX>>

An integrated T-septum waveguide diplexer for compact front-end applications

A novel T-septum waveguide diplexer for compact integrated front-end applications in modern communication systems is introduced. This 8.74/10.14 GHz X-band design is for 4% channel bandwidths. The size reduction is predominantly achieved by utilizing T-septum filter technology, which reduces the dimensions of a typical waveguide filter by a factor of four to five. Moreover, a considerably improved stopband behavior toward higher frequencies is obtained. Together with a height-reduced waveguide E-plane T-junction, the overall diplexer dimensions are less than (30 mm)/sup 3/. The computer-aided analysis and design are based on mode-matching techniques and optimization procedures, respectively. The channel filters are separately synthesized and fine-tuned by a final optimization to meet diplexer specifications. The theory is verified by measurements for the example of an X-band T-septum filter configuration.<<ETX>>

60 GHz radio wave propagation studies in an indoor office environment

60 GHz radio channel propagation characteristics in indoor office environment are addressed in this paper using full 3-Dimensional ray tracing of Wireless InSite and a simple deterministic 2-Dimensional model utilizing Ray-tracing technique. The comparisons are made with free space model and site-general prediction model of ITU-R. Values of the path gain, rms delay spread for sectoral horn and omni-directional antennas are presented. Also, path loss exponent and channel capacity values deduced from the simulation investigations.

Microstrip-to-substrate integrated waveguide aperture couplers

Multi-aperture couplers between microstrip circuitry and substrate-integrated waveguides are presented. The design procedure is described, and couplers formed by single-aperture and dual-aperture configurations are presented. It is demonstrated that the coupling can be as tight as 1 dB but that weaker coupling leads to more broadband and flatter coupler performance. Designs are carried out in an HFSS environment; comparison with CST validate the design procedure. Dimensions and parameters of all couplers are presented as guidelines for general design purpose.