This article presents, for the first time, new design and fabrication techniques for Hollow Substrate Integrated Waveguides (HSIWs), demonstrated in the nominal frequency from 21 to 31 GHz, for use in wireless communication applications such as 5G, IoT and robotics. The design and fabrication techniques introduced in this paper feature: 1) the use of low-cost rapid prototyping additive manufacturing based on polymer jetting (PJ), and 2) the use of commercially available through-substrate copper via transitions. In contrast to the conventional SIW designs and fabrications, this new approach does not rely on through-substrate via fabrication, hence avoiding some difficult manufacturing steps, such as through-substrate etching, via formation and via metallization, which are considered complex and expensive to implement. The 3D printed HSIWs in this article can achieve a propagation loss of lower than 1.56 Np/m (13.55 dB/m), which is considered one of the results with the lowest propagation loss achieved to date, when compared to the state-of-the-art.

In this paper, a harmonized fabrication and assembly process combining additive and subtractive manufacturing is introduced for the rapid manufacture of millimeter-wave components, especially those using hollow substrate integrated waveguide (HSIW). HSIW has been shown to have some significant advantages for millimeter-wave communications, radar and sensing systems, but its fabrication can be challenging. To pattern the metallic layers that form the top and bottom HSIW walls, as well as other structures such as microstrip lines and landing pads for integrated circuits and passive components, a subtractive fabrication process using a water-jet laser cutter was employed. To fabricate the dielectric substrate using low-cost Acrylonitrile Butadiene Styrene (ABS), with cavities for the waveguides, a Stratasys PolyJet 3D printer (Objet1000) was used. The HSIW components were then assembled using commercially-available through-substrate copper transitions, completely eliminating the process of throughsubstrate via-hole formation and metallization. The manufacturing techniques conventionally used for these vias are generally expensive and intricate at millimeter-wave frequencies. Therefore, the proposed fabrication and assembly process in this paper decreases the overall fabrication cost and complexity, and it is shown that this is achieved without compromising the performance of the millimeter-wave HSIW components. The measurement results show that a propagation loss of 13.55 dB/m (0.01355 dB/mm) is achieved for the first HSIW prototype, which is believed to be among the lowest propagation losses ever reported at these frequencies. The proposed harmonized fabrication and assembly technique has also a strong potential, by combining the advantages of additive and subtractive manufacturing techniques, to realize a new class of millimeter-wave components with the possibility of manufacturing conformal and flexible component shapes, based on the materials used.

This paper presents a compact triple-mode dielectric resonator bandpass filter based on a single waveguide cavity. Two barium titanate pucks are used in the design, placed in the middle of the metallic cavity to reduce the size of the filter. A third-order simplified Chebyshev bandpass filter is selected to verify the technique and simulated using HFSS software. The input and output coaxial probes are used to excite the degenerate EH11 modes, while the TM01 mode is excited using a vertical hole etched in the top of the barium titanate pucks. The resonator offers a size reduction ratio of about 15.6% compared with equivalent air-filled coaxial filters. The filter has finite transmission zeros on the high or low side of the passband.

This paper presents, a novel design of a Hollow Substrate Integrated Waveguide (HSIW), that is built by using both Subtractive and Additive Manufacturing technologies. Specifically, it utilizes Polymer jetting method to print an Acrylonitrile butadiene styrene (ABS) dielectric substrate and a water laser cutter system to produce smooth copper sheets as the top and bottom enclosures of the HSIW. Also, the fabrication process is utilizing mechanical through hole plating of commercially available prefabricated vias, eliminating the cost and complexity of performing vias fabrication and metallization process as in other SIW designs. The proposed waveguide covers 5G new radio frequency bands, specifically from 21 GHz to 31 GHz. It has a simulated and a measured attenuation constant of 0.636 Np/m and 1.56 Np/m respectively, for the whole operating frequency range and is among the lowest reported values to date. The proposed HSIW of this paper, can be compared with other state-of-the-art designs in terms of compactness, manufacturing cost and performance. The designed HSIW can be integrated with other planar circuits and can be used to build functional devices such as antennas or filters for 5G, robotics and IoT applications.