Pons Abenza, AlejandroArregui Padilla, IvánGómez Laso, Miguel ÁngelLopetegui Beregaña, José MaríaMartín Iglesias, Petronilo2024-07-152024-07-152024Pons-Abenza, A., Arregui, I.,Laso, M. A. G., Lopetegi, T., Martin-Iglesias, P. (2024) Design of an additively-manufactured self-supported all-metal coaxial-line X-band bandpass filter. IEEE Access, 12, 68171-68183. https://doi.org/10.1109/ACCESS.2024.3399745.2169-353610.1109/ACCESS.2024.3399745https://academica-e.unavarra.es/handle/2454/50285In this contribution, the design and manufacturing of an all-metal coaxial-line X-band bandpass filter is discussed. The device is 3D-printed as a self-supported structure without any dielectric inside the coaxial. The mechanical support between the inner and outer coaxial-line conductors is provided by means of λ/4 short-circuited stubs, which are also used in the bandpass filter design. The real transmission zeros (TZs) produced by the short-circuited stubs are responsible for a high filter selectivity. In order to enhance the filter performance, a second stage consisting in a coaxial-line stepped-impedance low-pass filter is integrated in the design to provide the rejection level required for the out-of-band behaviour. Following our design method, the bandpass and low-pass filters are designed separately, and a final matching step is performed to connect both and to achieve the aimed frequency specifications. In this way, a monoblock coaxial filter with very good in-band and out-of-band performance can by obtained by using an additive manufacturing (AM) procedure. Only the input/output (I/O) coaxial connectors will need to be assembled to the filter to perform the frequency measurements. The filters in this work can be seen as a first proposal towards more complex multi-functional monoblock structures using additively-manufactured coaxial technology, for highly-integrated RF chains. Other expected benefits beyond the compactness or lightweight are an increased RF shielding, electrostatic discharge risk reduction, and Passive Intermodulation (PIM) protection. In the paper, a prototype with a passband between 8 and 12 GHz is designed and manufactured, using a bandpass filter with three stubs and an integrated 15th-order low-pass filter, providing rejection for spurious frequencies up to 30 GHz. The filter is manufactured using Selective Laser Melting (SLM) and measurements show an excellent agreement with the simulations.application/pdfeng© 2024 The Authors. This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 LicenseBandpass filterCoaxial-line filterMetal 3D-printingStepped-impedance filterinfo:eu-repo/semantics/article2024-07-15info:eu-repo/semantics/openAccess