Compact Wideband Groove Gap Waveguide Bandpass Filters Manufactured with 3D Printing and CNC Milling Techniques

• Published in: Sensors (Basel, Switzerland) Vol. 23; no. 13; p. 6234
• Main Authors: Máximo-Gutierrez, Clara, Hinojosa, Juan, Abad-López, José, Urbina-Yeregui, Antonio, Alvarez-Melcon, Alejandro
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 07.07.2023; MDPI
• Subjects: 3-D printers; 3D printing; bandpass filter; Bandpass filters; Bandwidths; Broadband; Chebyshev approximation; CNC machining; Computer Simulation; Design specifications; Electric filters; Electric Impedance; Electromagnetic wave filters; Equipment Design; Frequency ranges; groove gap waveguide technology; Grooves; Impedance; Insertion loss; Lithography; lowpass filter; Manufacturing; Metallizing; Methods; Milling machines; Photopolymers; Printing, Three-Dimensional; Propagation; Prototypes; Resins; Satellite Communications; Silver; stepped impedance synthesis; Technology; Vacuum thermal evaporation; Waveguides; Spain; CNC machining; bandpass filter; groove gap waveguide technology; stepped impedance synthesis; 3D printing; lowpass filter
• ISSN: 1424-8220; 1424-8220
• DOI: 10.3390/s23136234

This paper presents for the first time a compact wideband bandpass filter in groove gap waveguide (GGW) technology. The structure is obtained by including metallic pins along the central part of the GGW bottom plate according to an -order Chebyshev stepped impedance synthesis method. The bandpass response is achieved by combining the high-pass characteristic of the GGW and the low-pass behavior of the metallic pins, which act as impedance inverters. This simple structure together with the rigorous design technique allows for a reduction in the manufacturing complexity for the realization of high-performance filters. These capabilities are verified by designing a fifth-order GGW Chebyshev bandpass filter with a bandwidth = 3.7 GHz and return loss = 20 dB in the frequency range of the WR-75 standard, and by implementing it using computer numerical control (CNC) machining and three-dimensional (3D) printing techniques. Three prototypes have been manufactured: one using a computer numerical control (CNC) milling machine and two others by means of a stereolithography-based 3D printer and a photopolymer resin. One of the two resin-based prototypes has been metallized from a silver vacuum thermal evaporation deposition technique, while for the other a spray coating system has been used. The three prototypes have shown a good agreement between the measured and simulated -parameters, with insertion losses better than = 1.2 dB. Reduced size and high-performance frequency responses with respect to other GGW bandpass filters were obtained. These wideband GGW filter prototypes could have a great potential for future emerging satellite communications systems.