Elliptical cavity resonators for dual-mode narrow-band filters

Abstract

A novel cavity resonator with elliptical cross section is proposed in order to realize dual-mode narrow-band filters without tuning and coupling elements. The absence of any discontinuity inside the cavities significantly enhances the unloaded Q, the ability to operate with higher power levels, and the ease of manufacturing. Proper choice of the ellipticity and of the inclination angle controls the desired coupling and tuning actions. Dual-mode coupling is generated by the step discontinuity between the input rectangular waveguide and an inclined elliptical waveguide. A rigorous full-wave electromagnetic model for this discontinuity has been developed and validated using a specialized hardware configuration. Experimental data compare very favorably with theoretical results. Representative prototypes of elliptical cavities exhibiting various degrees of coupling have been carefully measured proving the accuracy of the model and its applicability for narrow-band X-and Ku-band filter design. The full-wave analysis of a complete four-pole narrow-band elliptic filter at 12 GHz and the measured response of a corresponding prototype demonstrate the capability of achieving reliable results using the proposed approach.

Efficient modal analysis of arbitrarily shaped waveguides composed of linear, circular, and elliptical arcs using the BI-RME method

“…This complex device is a four-pole dual-mode filter successfully designed in [8], which is of great use for narrow-band applications. As can be seen in Fig.…”

“…Recently, and due to the mechanization effects of most common manufacturing techniques of waveguide components, the presence of rounded corners in rectangular waveguides has been under investigation in both guided [6] and radiating applications [7]. Another example of great practical interest is the elliptical waveguide, which has found increasing application in many passive microwave components, such as dual-mode [8] and triple-mode [9] filters, circular waveguide polarizers [10], radiators [11], resonators [12], and corrugated horns [13]. Therefore, the electromagnetic-wave propagation in hollow conducting waveguides of arbitrary cross section has become a problem of considerable practical interest, and many different approaches dealing with the calculation of the full modal spectrum of such waveguides have been published in the technical literature.…”

A Novel Multilayer Dual-Mode Substrate Integrated Waveguide Complementary Filter With Circular and Elliptic Cavities (Sicc and Siec)

“…The third step is to realize the coupling coefficients and external quality factor. The external quality factor is controlled by the width of the coupling aperture (W c1 , W c2 ) and given directly by (7). The coupling slot is located close to the maximum magnetic fields of the SICC/SIEC cavities.…”

“…They are denoted by T M cmnp and T M smnp modes, respectively. The resonant frequency for elliptic cavity with solid wall can be calculated by [6,7]:…”

“…A compact SIW filter with defected ground structure (DGS) was proposed in [2]. Besides, the substrate integrated circular cavity (SICC) and elliptic cavity (SIEC) are good choices in the design of good performance filters [4][5][6][7][8][9]. They not only have the same attractiveness as classical SIW filters, but also present higher quality factor and lower loss.…”