In the second episode of the Current Topics in 5G Technology series, Microwave Journal editors Pat Hindle and Gary Lerude discuss massive MIMO and mmWave technology with Andreas Roessler, technology manager at Rohde & Schwarz, and Earl Lum, president of EJL Wireless Research. Andreas and Earl discuss the pros and cons of each technology and the challenges that need to be addressed. The series is sponsored by Rohde & Schwarz. R&S has a free eBook available on 5G NR at http://rsna.us/mwj_5g_ebook and Guide to measuring phased array antennas here https://www.microwavejournal.com/ext/resources/Podcasts/RohdeSchwarz5G/Massive_MIMO_misc_en_5216-2018-92_v0100.pdf.