Monolithically-integrated 3D printed coaxial bandpass filters and RF diplexers: single-band and dual-band

Abstract

The manuscript reports on additively-manufactured (AM) coaxial-resonator-based bandpass filters (BPFs) and RF diplexers. A monolithic integration concept using stereolithography apparatus (SLA) is proposed and discussed in detail. Coupled-resonator-based synthesis alongside full-electromagnetic-based design methods is used for the design of the monolithic filters and RF diplexers. In particular, the paper discusses a new external coupling mechanism for dual-band BPFs that allow to independently control the coupling in each of the BPF passbands. Furthermore, a novel coaxial transmission line-type T-junction is proposed for the design of single- and dual-band RF diplexers. For practical validation purposes, multiple BPF and RF diplexer prototypes were designed, manufactured and tested at S- and C-band demonstrating the applicability of the proposed concept to low-cost, low-loss and low-weight RF components with complex geometrical features.

Dual-Band Bandpass Filters Using 3D Printed Dual-Mode Nested Spherical Resonators

“…The diameter of the holes is selected so that they don't radiate at the center frequency and as such have no impact in the passband II. As shown, the proposed dual-band filter has lower IL and higher than the majority of the reported 3D printed dual-band BPFs and especially the ones in [13]- [14]. Furthermore, the dual-mode nested-spherical resonator concept is uniquely shown in this work for the first time for the realization of compact dual-band BPFs.…”

“…Additive manufacturing (AM) techniques (or 3D printing) have been increasingly explored for manufacturing 3D resonators-based microwave dual-band BPFs, such as the spherical resonator-based configuration in [7], the ellipsoidal resonator-based in geometry in [8], and the coaxial resonatorbased dual-band BPFs in [13]- [14]. Compared to traditional CNC machining techniques, AM facilitates filters with higher geometrical complexity and is potentially suitable for monolithic 3D integration.…”

“…Compared to traditional CNC machining techniques, AM facilitates filters with higher geometrical complexity and is potentially suitable for monolithic 3D integration. Various examples of monolithically-integrated 3D printed BPFs have been shown to date [9]- [14] and have demonstrated improved performance, smaller size and weight than their CNC-machined counter parts. However, to the best of the author's knowledge, monolithic AM-based integration concepts haven't been demonstrated for multi-band nested spherical BPFs with the exception of the work [13]- [14] which however is focused on coaxial resonators where dual posts were used for the realization of dual-band BPFs and the concepts in [15]- [16] which is focused on conventional cylindrical and spherical resonators.…”

Acoustic Wave Resonator-Based Bandpass Filters With Continuously Tunable Fractional Bandwidth

“…Bandpass filters (BPFs) with electronically reconfigurable transfer functions are highly-desirable in these systems to enhance existing capabilities, and miniaturize their size [2]. The majority of the tunable BPFs that have been presented to date are large in size and are based on low-quality factor (Q) (around 50-150 for lumped-element (LE) and microstrip-type configurations [3]- [4], and 300-800 for coaxialresonator-based components [5]) resonators. These also exhibit high levels of in-band insertion loss (IL) between 3-10 dB [4], [6].…”

Additively Manufactured and Monolithically-Integrated Triple-Mode Post-Loaded Cavity-Resonator-Based Bandpass Filters

“…Recently, monolithic SLA-based integration concepts were reported for the manufacturing coaxial cavity-based filtering components [45], [46], [47], [48], [49]. They demonstrated competitive RF performance characteristics and significantly reduced volume and weight when compared to their splitblock counterparts.…”