Just as quantum mechanics imposes a rough floor size on chip process design, so more mundane laws of physics constrain miniaturization of radio antennas for small form factor IoT devices. This is of course independent of the radio protocol, whether we are talking about 5G, Zigbee, LoRaWAN, NB-IoT, WiFi or any of the other options for either indoor or outdoor wireless communication over varying ranges and frequencies. There is no absolutely precise limit, but the rule of thumb is that the antenna cannot be shorter than one quarter of the wavelength of signals it is designed to receive. This means that antenna can be smaller at higher frequencies and at 70 GHz, about the highest frequency practical for mobile and…