# The role of a DC/RF Amplifier in wireless electricity

#### Mariemation

Joined Sep 26, 2016
18
Hi

I am trying to create a project about wireless electricity transfer, and as I was reading about Witricity's system I came across the term DC/RF Amplifier, which I am not sure what it means. I am new to electronics (and to physics in English in general, I am used to French instead) so I don't know a lot of the terminology. In the document I was reading, it says: "A high efficiency switching amplifier converts the DC voltage into an RF voltage waveform used to drive the source resonator." which I didn't understand either (precisely the parts in bold).
Here's the document I as reading.

I appreciate any help around the subject.

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#### nsaspook

Joined Aug 27, 2009
9,454
DC/RF Amplifier, It's just a fancy word for RF transmitter. The Witricity promoters get no bling (Evanescent wave coupling instead of near field) from using old school words that show Witricity to be just another rehash of old RF transformer technology. The source resonator acts as the primary for a tuned (resonant) RF transformer magnetic circuit. The resonator impedance LC is chosen so that the magnetic field dominates the transfer of RF energy to the secondary remote coupling coil. This keeps most of the field energy in the near-field (non-radiative) and reduces (radiative) antenna effects with its associated radiation losses if designed and tuned properly.

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#### Sensacell

Joined Jun 19, 2012
2,985
So many companies are hyping and re-spinning the same old tech in the interest of making a press release.

Wireless power for the most part is a way to waste 30% more energy, while being horrifyingly lazy.
It's one of the most environmentally unfriendly new ideas I can think of.

1) all that wasted power adds up, it's never more than 70% efficient, often much less -

2) all that extra tech hardware that ends up in garbage heap -

3) all that extra money you spend - $.01 worth of wire and connector is replaced with$1.00 worth of of kit.