Abstract
A microstrip-fed air-substrate-integrated waveguide (ASIW) slot array with high efficiency and low cost is presented. The design cuts out the substrate material within SIW, replaces the vias with metallic sidewalls, and uses a simple microstrip line-waveguide transition to feed the slot array. Radiating slots are cut on a 5-mil brass-plate, which covers the top of the substrate cutout to resemble a hollow waveguide structure. This implementation provides a simple and efficient antenna array solution for millimeter-wave (mm-wave) applications. Meanwhile, the fabrication is compatible with the standard printed circuit board (PCB) manufacturing process. To demonstrate the concept, a 4-element ASIW slot array working at the n257 band for 5G communications was designed using low-cost Rogers 4350B and FR4 substrate materials. Our simulation result shows 18% more efficiency than a conventional SIW slot array using the same substrate. The fabricated prototype shows |S11| < −15 dB over 27–29 GHz and a peak realized gain of 10.1 dBi at 28.6 GHz. The design procedure, prototyping process, and design analysis are discussed in the paper.
Highlights
With the rapid development of 5G communication systems and mm-wave automotive radars, better quality, low-cost, and low-loss antennas are in high demand
To eliminate the metallic vias, simplify the transition, and further improve the antenna efficiency, we introduce a tapered microstrip-fed air-Substrateintegrated waveguide (SIW) (ASIW) slot array with copperplated side walls
A high-efficiency and low-loss ASIW slot array design is proposed in this paper
Summary
With the rapid development of 5G communication systems and mm-wave automotive radars, better quality, low-cost, and low-loss antennas are in high demand. Building high-efficiency antennas at mm-wave requires expensive low-loss substrate materials and high-precision manufacturing processes. To overcome these limits, the air-filled structure of the traditional rectangular waveguide has been reconsidered and gradually implemented using the current substrate-integrated circuit (SIC) technique. To eliminate the metallic vias, simplify the transition, and further improve the antenna efficiency, we introduce a tapered microstrip-fed air-SIW (ASIW) slot array with copperplated side walls. The radiating slots are cut on a 5-mil brass layer, which covers the top of the substrate cutout. Electronics 2021, 10, 338 stronger than copper and most 5-mil substrates, this thin layer is still susceptible to bending. There can be small air gaps between adjacent screws that can cause wave leakage and reduce antenna efficiency. DDiimmeennssiioonnssoofftthhee2288GGHHzzAASSIWIWsslolot taarrraray.y(.a()a)OOvevrearlallsliszieze(b()bD) Dimimenesniosinosnosfotfhteh5e-m5-iml tiol p stloopttseldotbtreadssbrpalasstep(lca)teD(icm)eDnismioennssoiofnthseowf tahveewguaivdeegauniddemaincdromstriciprolsintreip(MlinSLe)(-MwaSvLe)-gwuiadveegtruaindseition. transition
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