Hydrogen Line Radio

Hydrogen is the first and foremost of elements. It has an atomic number of 1 and a single atom is comprised of  one single positively charged proton and a single negatively charged electron. It is estimated to comprise 75% of all the mass in the universe. We think of it usually in the from of hydrogen gas which is actually dihydrogen or H₂, but it has many other forms. What on Earth does this have to do with radio? Hydrogen can emit radio waves.

So let me do a little background here. Today the pedestrian understanding of Atoms isn't much better than Leucippus. It's usually seen as an the smallest unit of matter. It's seen as stable, and foundational. This is of course destroyed by any understanding of subatomic particles... but even these basic atomic building blocks are in flux. Electrons for example can jump between energy levels. It can jump up a level by absorbing light. Then by emitting light if can jump down a level. There are a total of 5 levels each which has a known energy state. More here and here.

Level	Energy
1	-13.6 eV
2	-3.4 eV
3	-1.51 eV
4	-0.85 eV
5	-0.54 eV

When Hydrogen changes energy states it also releases some of that energy as radio waves. This electromagnetic radiation is at a frequency of 1420.40575177 MHz.This spectral line is called "the hydrogen line. The frequency is within the microwave band and is observed in radio astronomy. Actually this "hiss" was first detected in the 1930s.  Dr Hendrik van de Hulst predicted that this would be caused by Hydrogen.  This was then proven in 1951. The frequency works out to a physical  wavelength of 21.1 cm. That's why Carl Sagan and Frank Drake considered it universal enough to use as a unit of measure on the Pioneer plaque to be shot into space.

Regenerative Microwave Converter

This December, Nihon Dengyo Kosaku Co. debuted a microwave regenerative converter for 2.45GHz-band rectennas. consumers don't think about it, but microwave ovens are fundamentally similar to microwave antennas. The primary difference is that a microwave oven is designed to contain the "broadcast" so it can be converted to heat energy when it encounters mass i.e. your lunch. This process is called dialectic heating. Don't be surprised this gadget was invented in China, the microwave itself was invented in Japan in 1955. It wasn't introduced to Americans until Amana imported it in 1967.

So here's how this widget comes in. Your microwave isn't 100% efficient. Actually if you've ever looked at it's power consumption you already kow it's a bit of a hog when it's running. That's because much of the microwaves just bounce around and dissapate, they are not all absorbed by their intended target. That  means a portion of those aren't converted to heat and are totally wasted. An average consumer microwave oven consumes 1100 watts of electricity to produce 700 watts of power. That's an efficiency of 64%, though it'd obviously vary. To be fair a lot of that is just heat loss.

This rectenna receives the microwaves in your microwave oven and converts that surplus energy to electricity. The reason this regenerative converter works only at a frequency of 2.45 GHz, is that it's also the frequency that all consumer microwaves operate on. Commercial microwave ovens operating 915 MHz.  I have read that some countries also use 433.92 MHz. This would be most efficient if it were used to reduce the power draw of the microwave itself, but it's as yet unknown if it will even go into commercial production. More here.