RF energy, through the use of high-power solid-state amplifiers and feedback, could change the way we cook, light our homes, and power our vehicles. These applications are still in their infancy, but there's real potential.
A certain person in my household has been known to burn microwave
popcorn—fortunately, without starting a fire. What's really needed here
is a microwave oven that detects the changes taking place in food as it
cooks and makes the appropriate adjustments. Such an oven is now
possible, though it might be a few years before it's practical and
RF energy is on the cusp of bringing changes to cooking, lighting,
industrial heating, automotive spark plugs, and a host of other
applications. It's made possible through the development of RF
transistors that can provide sufficient power at the right frequencies,
namely the 2.45 GHz ISM band. Yes, the same band used by Wi-Fi and
As with any new technology, RF energy applications come with
engineering challenges such as thermal dissipation, cost, size, and
measurement. At EDICON
2016 in Boston, I met with Klaus Werner, Executive Director of the RF
Energy Alliance, who also gave a presentation that day. After the
conference, I spoke with Mark Murphy, Senior Director Marketing and
Business Development for RF Power at MACOM and with Robin Wesson, Advanced Applications Architect at Ampleon.
"RF energy could change the way we cook food," said Werner, "but it's
being used in other applications." He explained that RF energy,
generated by RF transistors in power amplifiers, could replace the
magnetrons in microwave ovens. By generating energy with semiconductors
and more than one antenna (Figure 1), microwave ovens could
produce energy sufficient for cooking and adapt to changing conditions
as food cooks. That can result in more even cooking than we currently
get from our microwave ovens, which essentially operate as on/off,
open-loop systems. Instead, the next generation of microwave ovens will
have complete closed-loop control. Some of today's ovens have
mode-stirrers or turntables to attempt to produce a uniform field inside
the cavity while others use humidity sensors that provide some
feedback, but not enough, for the kind of control needed.
Figure 1. Power transistors such as these from MACOM and Ampleon can produce 300 W or power at 2.45 GHz. (The Ampleon device is rated at 250 W, but a 300-W version is available.) MACOM uses a GaN-on-silicon process while Ampleon uses laterally diffused metal-oxide-silicon (LDMOS).
Read the complete article, RF energy: Measurements improve cooking, lighting, and more, on EDN.