Low-Cost Empty Substrate Integrated Waveguide Slot Arrays for Millimeter-Wave Applications

In this letter, two slot arrays with high radiation efficiency are proposed based on the empty substrate integrated waveguide (ESIW) technology. The arrays consist of four FR-4 substrate layers that function as cavity loading, radiation slots, ESIW feeding network, and feeding port, respectively. The 1 × 6-slot array shows a measured -10 dB bandwidth of 12.7% (36.1- 41.0 GHz) with a measured maximum gain of 15.5 dBi and radiation efficiency of 90.7% at 38 GHz. The 8 × 6-slot array shows a measured -10 dB bandwidth of 12.1% (36.4-41.1 GHz) with a measured maximum gain of 24.0 dBi and radiation efficiency of 86.5% at 39 GHz. Additionally, stable radiation patterns are obtained in the operating band. These arrays provide a low-cost way for broadband millimeter-wave wireless applications including the fifth-generation mobile communications.