“…Whistler‐mode waves were first discovered on the ground over a century ago (Preece, 1894), and were since frequently observed by ground‐based detections (Stenzel, 1999). The existence of Earth‐magnetosphere/ionosphere waveguide is widely accepted, which guides whistler‐mode waves to reach the ground (Ohta et al., 1996; Stenzel, 1999). The most common waveguides are field‐aligned density irregularities (also called density ducts) supported by theoretical and numerical works (Hanzelka & Santolík, 2019; Smith et al., 1960; Streltsov et al., 2006), which have been frequently detected by satellite‐based measurements (Carpenter et al., 2002; Darrouzet et al., 2009) and ground‐based imaging telescope (Loi et al., 2015).…”