Manos Tentzeris, a researcher from the Georgia Tech School of Electrical and Computer Engineering has invented a new type of antenna that could make harnessing the energy of otherwise wasted radio waves more easy and could yield a higher efficiency on a broader range of frequencies.
“There is a large amount of electromagnetic energy all around us, but nobody has been able to tap into it,” said Manos Tentzeris, a professor in the Georgia Tech School of Electrical and Computer Engineering who is leading the research. “We are using an ultra-wideband antenna that lets us exploit a variety of signals in different frequency ranges, giving us greatly increased power-gathering capability.”
The most interesting fact is that the antenna Tentzeris and his team discovered is printed on paper, with classic inkjet technology, which you can also find in your home printer. The only exception is that the ink contains nanoparticles of silver and other metals, combined after a “unique in-house recipe.” It can harvest an energy spectrum having frequencies from 100 MHz to 15 GHz, he clims, so the energy density is quite something. Tentzeris also says he expects future versions to generate up to 1 milliwatt or more.
“We can now print circuits that are capable of functioning at up to 15 GHz — 60 GHz if we print on a polymer,” says Rushi Vyas, a graduate student who is working with Tentzeris and graduate student Vasileios Lakafosis on several projects. “So we have seen a frequency operation improvement of two orders of magnitude.”
Applications are wide: from powering temperature sensors to material stress monitoring in buildings, and generally the monitoring of anything remote or mobile, like perishable foods or RFID devices.
The concept behind this is not new at all. In fact, if you take a rectifier diode bridge (you can build one yourself) with four germanium diodes, attach a long antenna to it and also put in some capacitors linked to the diodes, you’ll end up with an energy scavenging circuit just like Tentzeris made with his more efficient antennas.
I remember that, as a kid, I’ve been playing with such contraptions a lot. I didn’t care much about the energy part then, but I was more into listening to the radio through a simple receiver made from a germanium diode, a phone earpiece and a long wire – seasoned old-times lovers who grew in the countryside know what I’m talking about – don’t you?