A Wideband Transition Design Technique From RWG to SIW Technologies

Abstract

Efficient wide-band transitions play a critical role in integrating substrate-integrated waveguide (SIW) and air-filled substrate-integrated waveguide (AFSIW) systems with conventional rectangular waveguide (RWG) systems in millimeter wave communication. However, existing techniques lack a systematic design approach, overlook mode purity, encounter performance issues, involve tedious optimizations, and feature complex structures. This paper presents a first-of-its-kind design technique that addresses these limitations, enabling seamless transitions from RWG to both SIW and AFSIW. For the first time, a clear and systematic design flow is introduced, covering both transition scenarios. The proposed technique eliminates the need for separate design procedures, simplifying the process, reducing complexity, and offering a cost-effective solution with state-of-the-art performance. The key innovation lies in the analytical expression for the shortest transition length, derived for both SIW and AFSIW cases, facilitating the design process and optimizing transition performance. The effectiveness of the design flow is extensively validated through four design examples, evaluating mode purity, reflection coefficient, and insertion loss. The results demonstrate excellent performances, confirming the accuracy of the approach. Furthermore, a fabricated prototype achieves remarkable results with an insertion loss of 0.35 dB and a relative bandwidth of 40%, exhibiting state-of-the-art performances when compared to reported works in the literature. In summary, the novel design technique enables seamless wide-band transitions from RWG to both SIW and AFSIW, offering a unified approach with state-of-the-art performance.INDEX TERMS Wideband, millimeter-wave, rectangular waveguide, substrate integrated waveguide, air-filled substrate integrated waveguide, RWG to SIW, RWG to AFSIW

A Millimeter Wave Air Filled SIW Horn Antenna with Tilted Beam

“…This characteristic can be exploited to develop a Multi-beam Array for modern communication applications, as discussed in [5], [13]. [3], [4]. The tapered transition is designed using the technique reported by the authors in [3], [4].…”

“…[3], [4]. The tapered transition is designed using the technique reported by the authors in [3], [4]. The E-field distribution shown in Fig.…”

“…5 (b). The proposed array is fed using WR-15 to SIW transition by using the techniques reported by the authors [3], [4].…”

“…However, capitalizing on these advantages requires overcoming atmospheric absorption and multi-path effects, which degrade signal quality [1]. Tilted-beam horn antennas [1], [2] offer a promising solution, particularly those leveraging emerging Substrate Integrated Waveguide (SIW) technologies like Air-filled SIW, due to their low profile, superior performance, low cost, manufacturability, and compatibility with planar circuits [3], [4]. Moreover, these antennas offer the potential for developing multi-beam antenna arrays, which are crucial for urban-air mobility (UAM) applications [5].…”

“…On the other hand, air-filled SIW (AFSIW) technology remains completely unexplored, with no reported work. This is particularly noteworthy because AFSIW offers significant advantages over SIW [3], [4], as discussed previously. Furthermore, AFSIW antennas in the V-band have yet to be investigated.…”