Compact Wideband Hybrid Filters in Rectangular Waveguide With Enhanced Out-of-Band Response

Abstract

This paper describes the design procedure of a compact wideband waveguide filter, based on stepped impedance resonators (SIR) and a combined usage of capacitive and inductive coupling irises, that provides a significant improvement in the out-of-band response of the filter with respect to the state-ofthe-art. In addition to theory, several filter prototypes have been designed and manufactured. A detailed sensitivity analysis has been also carried out. Finally, simulations and measurements are compared, showing very good agreement, thereby fully validating the new filter topology. Index Terms-Aggressive space mapping, band-pass filters, hybrid (inductive and capacitive) irises, stepped impedance resonator and wideband.

Hybrid Wideband Staircase Filters in Rectangular Waveguide With Enhanced Out-of-Band Response

“…To conclude this section, we have compared the performance of the filter discussed in this article with the hybrid SIR filter (filter I) discussed in [17]. The results are shown in Fig.…”

“…The objective of our filter design is to satisfy the requirements in Table I and, at the same time, to extend as much as possible the spurious-free frequency range above the passband. It is important to note that the above specifications have been already used in [17]. We will use them again in the remainder of this article in order to compare the improvement obtained with the new filter structure that we propose.…”

“…One additional possibility is to design bandpass filters using hybrid couplings, that is, both capacitive and inductive irises. Recently, two contributions, namely, [16] and [17], have demonstrated the use of SIRs in conjunction with capacitive and inductive coupling irises (hybrid filter) in order to improve the out-of-band performance. The structures discussed in [16] and [17] provide a wide spurious-free region above the filter passband implementing an important reduction of the strength of the harmonic resonances.…”

“…Recently, two contributions, namely, [16] and [17], have demonstrated the use of SIRs in conjunction with capacitive and inductive coupling irises (hybrid filter) in order to improve the out-of-band performance. The structures discussed in [16] and [17] provide a wide spurious-free region above the filter passband implementing an important reduction of the strength of the harmonic resonances. However, this improvement comes with an expensive manufacturing process and a rather complex design procedure.…”

Investigation of the cutting plane and tolerance analysis of cross-coupled W-band waveguide filters with multiple transmission zeros by source to load cross-coupling

“…Several techniques exist in order to shift the spurious modes as far away from the passband as possible, e.g. [22,23]. The filters proposed here are not designed to fulfill certain rejection requirements above the W-band frequency range.…”