This letter presents a simple and cheap metal-plating procedure for plastic 3-D printed microwave components The devices are built using a Stereolithographic printer and then metalized by a two-step process consisting in a silver-painted substrate followed by copper electrodeposition The method achieves good adhesion of the metal to the plastic body and high conductivity Resonators and $X$ -band filters have been fabricated and tested, showing excellent performance in terms of dimensional accuracy and low loss, with quality factors better than 6500 The technique can be usefully employed for fast and cheap prototyping of microwave components at least up to the $X$ -band

Simple High-Performance Metal-Plating Procedure for Stereolithographically 3-D-Printed Waveguide Components

Three-dimensional (3D) printing, additive manufacturing (AM), digital manufacturing, and free-form fabrication are some of the synonymous expressions commonly used to identify the new class of processes through which objects are built by selectively adding material, usually layer by layer, instead of subtracting material, as in conventional machining techniques like chemical etching, laser-cutting, milling, and electroerosion [1].

3D Printing of Microwave and Millimeter-Wave Filters: Additive Manufacturing Technologies Applied in the Development of High-Performance Filters with Novel Topologies

This paper presents a parametric study of classical additive 3D-printing settings for use on conductive filaments in applications for high-frequency topologies. First, a wideband characterization was conducted, printing a microstrip transmission line using a conductive filament with variations of typical 3D-printing settings, such as layer height, infill percentage, and infill pattern. The measurement results show a dependence on the high-frequency transmission parameters with respect to the infill percentage and the infill pattern. Finally, two antennas were 3D-printed using conductive material, a microstrip patch, and a low-weight pyramidal horn antenna. The results for the patch agree with the losses found on the line measurements, while the low-weight pyramidal horn exhibits no major differences compared with its equivalent antenna, made using perfect conductors.

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Parametric Study of 3D Additive Printing Parameters Using Conductive Filaments on Microwave Topologies

The dual-mode characteristics of the half-mode substrate-integrated rectangular cavity (HMSIRC) are systematically analyzed for the first time and experimentally demonstrated by two planar substrate-integrated waveguide (SIW) dual-band bandpass filters (DBBPFs) with widely separated passbands. The mode spectrums in an HMSIRC and their constraint relationships are comprehensively investigated first to explore the realizable frequency ratio of the second mode (TE301 or TE102) to the first one (TE101). The maximum frequency ratio of 1.63 for TE301/TE101 and 1.72 for TE102/TE101 can be achieved considering the spacing between the second and third resonances. Subsequently, the formulas of determining the physical dimensions of the dual-mode HMSIRC are derived and validated. The factors impacting the unloaded quality factor Q u of the HMSIRC are also discussed and the square single-mode quarter-mode substrate-integrated rectangular cavity has been investigated. Two compact planar SIW DBBPFs, including a third-order direct-coupled one with frequency ratio of 1.5 based on TE101 and TE301 dual-mode HMSIRC, and a fourth-order cross-coupled one with frequency ratio of 1.7 based on TE101 and TE102 dual-mode HMSIRC, are synthesized and designed for verification.

Dual-Mode Characteristics of Half-Mode SIW Rectangular Cavity and Applications to Dual-Band Filters With Widely Separated Passbands

Cellular ceramic structures (CCSs) have promising application perspectives in various fields. Recently, additive manufacturing (AM), usually known as three-dimensional printing (3D printing), has been increasingly adopted to produce CCSs. Usually, the structural properties of additively manufactured cellular ceramic structures (AM-CCSs), i.e., lightweight characteristics, load-bearing capacity, toughness, unconventional properties, are traditionally investigated. Interestingly, AM technologies have a significant advantage in achieving the structure–function integration for CCSs. Functional properties, e.g., electromagnetic property, acoustic property, thermal property, of CCSs can be achieved during the structural design synchronously. In this review, firstly, the AM technologies for CCSs are comparatively introduced. Then, structural AM-CCSs are summarized. After that, structure–function integrated AM-CCSs are further introduced in detail. Finally, challenges and opportunities towards structure–function integrated AM-CCSs are forecasted. This review is believed to give some guidance for the research and development of CCSs. 

Additive manufacturing of cellular ceramic structures: from structure to structure-function integration

A dual-mode dual-band cavity is proposed for the integration of compact dual-band filters with widely separated passbands. The basic structure is a cavity working on two distinct dual-modes, realizing a four-pole dual-band filtering function. An intermediate structure is also designed to validate coupling between dual-band cavities. Finally, two dual-mode dual-band cavities are coupled together for implementing an eight-pole filter with two passbands at 5 and 7.5 GHz, respectively. Prototypes are fabricated and measured for validating all designs, showing the relevance of the proposed concept.

Dual-Mode Dual-Band Bandpass Cavity Filters With Widely Separated Passbands

This paper presents a concept of a tunable cavity resonator composed of a resonating cavity and a dielectric perturber. This tunable resonator is designed and measured to prove the tuning mechanism obtained by varying the angle of rotation of the perturber. A rotation from 0 to 90 produces a tuning ratio of 1:1.25, i.e., a tuning range of 22.2% around 11.5 GHz while maintaining an unloaded Q factor between 1500 and 2300. After this first experimental validation, a third-order bandpass filter is then designed and measured using the same base principle. Using a single mechanical movement, all three resonators’ perturbers are synchronously rotated to create a third-order Chebyshev bandpass filter maintaining a 516±38-MHz bandwidth (for a return loss better than 10 dB) from 9.915 to 12.189 GHz. A 20.6% tuning range is then obtained at approximately 11 GHz with an estimated Q factor from 1400 to 2150. These performances have been obtained by using specifically shaped dielectric perturbers, which have been made by a ceramic additive manufacturing (AM) process (stereolithography). This technology has enabled the perturbers’ specific geometries and embedded supporting elements to be feasible. A sixth-order Chebyshev bandpass filter has also been theoretically proposed using full wave simulations.

Continuously Tuned Ku-Band Cavity Filter Based on Dielectric Perturbers Made by Ceramic Additive Manufacturing for Space Applications

This paper compares several designs of lossy filters for receiver subsystems in satellite transponders. The reference design is a microstrip filter made of coupled hairpin resonators. Two approaches are investigated for improving the flatness of the reference design. The first approach combines nonuniform quality factor (Q) resonators in a transversal network. The second approach uses an inline network with resistive cross couplings. Lossy filter designs are compared to the reference, considering the same specifications and the same technology. The inline network with resistive cross-couplings is finally modified for designing absorptive filters, which protect the receiver from reflected waves. All filter configurations are fabricated and measured, showing a good agreement with electromagnetic simulations.

Design of Microstrip Lossy Filters for Receivers in Satellite Transponders

This paper presents an overview of the possibility offered by 3D plastic printers for a quick, simple and affordable manufacturing of working filters and other passive devices such as antennas. This paper thus goes through numerous examples of passive devices made with the Fused Deposition Modeling (FDM) and material jetting (Polyjet©) technologies and will highlight how they can now be considered as a solid companion to RF designers during an optimization process up to Ku and higher bands.

3D printing of microwave passive components by different additive manufacturing technologies

Taking advantage of multilayer technologies, a vertical evolution of the interdigital topology is proposed with its associated synthesis method. In order to validate this filter topology, a 4-pole filter, centered at 10 GHz, and an 11-pole filter, centered at 6 GHz, have been designed and fabricated using low-temperature co-fired ceramic (LTCC) technology. Two other multipole filters have also been designed showing a large surface reduction with respect to equivalent interdigital filters. LTCC technology has been chosen for fabricating the filters, but the proposed topology can also be implemented with other multilayer technologies.

Aurelien Perigaud

Papers

Dual-Mode Dual-Band Bandpass Cavity Filters With Widely Separated Passbands

Continuously Tuned Ku-Band Cavity Filter Based on Dielectric Perturbers Made by Ceramic Additive Manufacturing for Space Applications

Design of Microstrip Lossy Filters for Receivers in Satellite Transponders

3D printing of microwave passive components by different additive manufacturing technologies

Synthesis of Vertical Interdigital Filters Using Multilayered Technologies