Admittance matrix formulation of waveguide discontinuity problems: computer-aided design of branch guide directional couplers

Abstract

A computational scheme is proposed that can be applied to the analysis of cascaded waveguide discontinuities of alternating boundary-enlargement and boundary-reduction type. Based on the mode-matching technique, the proposed procedure makes use of the admittance matrix characterization of waveguide stubs. With respect to the conventional S-matrix formulation, it leads to a notable reduction of the computational effort, particularly for lossless structures. At the same time, the criterion for avoiding relative convergence problems can be satisfied. The procedure has been used to set up a very accurate and efficiency computer-aided design tool of branch guide couplers (BGCs). These are key elements of beam-forming networks for multicontoured beam satellite antennas and have to be designed with very high accuracy so as to eliminate the necessity for tuning the components realized. Design accuracies better than 0.1 dB in Ka-band are demonstrated by experimental result

Analysis acceleration in the design of frequency selective surfaces using parametric techniques

“…After this computation, the moment matrix and the RHS for any parameter point in the specified parameter ranges can be rapidly evaluated by simply interpolating the expansion coefficients α m and by calculating the sum (2). This evaluation, which we call post processing, is much faster than the fullwave computation.…”

“…, p N ) in the zone. For each considered set, the Kriging results are compared with results obtained by reduced order model techniques applied to the minimum norm problem associated to (2). The extension of the set stops once a required level of accuracy of the expansion coefficients α m is achieved.…”

“…Usually, the equivalent networks have as many input and output ports as the number of modes used to represent the fields at the transition. To reduce computational time and to avoid stability problems [2], the IEMEN method resorts to an equivalent network (represented by an impedance/admittance matrix) in terms of only accessible modes. They are the modes (propagating or evanescent) used in the representation of the field at the FSS transition that also contribute to the interaction with adjacent FSS transitions.…”

Modelado con técnicas modales de estructuras de microondas basadas en guías N-furcadas arbitrariamente rellenas con materiales

“…Este fenómeno se observa en todos los casos, y por ello, en los estudios de la convergencia que se realicen a continuación, se representará únicamente el valor del modo fundamental. Desarrollo teórico [35] La Fig. 2.6 muestra los módulos de los parámetros S 11 y S 21 de los modos TE 10 , TE 30 y TM 12 cuando se incide con el TE 10 desde la primera.…”

“…3.14 muestra un corte longitudinal en plano E de un acoplador direccional de 6-dB de líneas bifurcadas [30], [35].…”