D. Cañete Rebenaque

Enhanced topologies for the design of dual‐mode filters using inductive waveguide structures

This paper presents novel topologies for the design and realization of microwave filters combining dual-mode and single-mode cavities in all-inductive waveguide technology. Examples of orders 3–5 with one or two transmission zeros are synthesized and designed, in order to demonstrate the validity of the proposals. All the coupling schemes explored exhibit the zero-shifting property, so the transmission zeros can be easily placed above or below the passband. A four-pole dual-band-pass filter is also designed to show the flexibility offered by the novel structures. A prototype of this dual-band filter has been manufactured and tested in order to provide experimental validation for these new structures. Important aspects of synthesis techniques, required to obtain the associated coupling topologies and to perform the final physical design of the waveguide filters, are also addressed in this paper.

Compact implementation of transmission zeros using the zero shifting property

In this contribution we propose a structure for the implementation of transmission zeros using the zero shifting property. In previous implementations, two open loop resonators operating at different resonances were employed. In the configuration, one of the open loop resonators is substituted by a short-circuited transmission line, thus resulting into a more compact structure. Also, the new configuration is able to support larger bandwidth than traditional designs. This is due to an improved capability to increase the coupling between the input and output lines to the new short-circuited transmission line. For this purpose a new cross-shaped coupling structure is proposed. A manufactured prototype has been successfully tested. The results show the usefulness and validity of the new structure.

Efficient Analysis of Inductive Multiport Waveguide Circuits using a Surface Integral Equation Formulation

This paper presents a simple and alternative approach for the analysis of inductive multiport waveguide microwave components. The technique uses a surface integral equation formulation to treat both metallic and dielectric objects inside the component structure. In order to avoid the relative convergence problem of other techniques based on mode matching, a novel port treatment is used. The technique is based on the application of the extinction theorem using the spatial representation of the Greens functions and image theory. Different complex H-plane structures are analyzed, including microwave bandpass filters with elliptic transfer functions and waveguide bends with dielectric posts. Results show the high accuracy and versatility of the new technique derived.