Radio spectra for Betelgeuse at VLA wavelengths spanning 1972–2012. The continuous line represents the radio spectrum from Newell & Hjellming (1982) and includes measurements up to 90 GHz. The dashed line is the almost identical spectrum from Drake et al. (1992). The dash-dotted line is the radio spectrum that best fits the more recent data between 1996–2004 and is described by F_ν = 0.18 mJy ν^1.33. The flux density from the e-MERLIN 5.2 cm observation and a 100 GHz flux density measurement from Harper et al. (2009) are also shown.