Comment Re:Max Depth? (Score 1) 140
The antenne *is* the drill bit - and the quarter wave rule is to stop it acting as a real antenna and broadcasting microwaves all round the room. Below 1/4 wavelength, some undecribed mechanism creates intense heating just below the drill bit, which is where you want to drill.
That's what I said: the drill is a highly directional antenna. The undescribed mechanism is the radiation energy absorbed by the material which is being drilled. (Energy equals heat, among some other things.)
They can't move the drill forward without moving the (presumably non-conducting) chuck, or all their micropwave energy will radiate sideways, gently heating that which they do not want to heat and failing to heat that which they want to drill.
Yes, you're right about that. I first thought that the mechanism of drilling is as follows: heat the material with microwaves and when the material is sufficiently hot/soft, push the drill/antenna as deep as you can and repeat. The problem is that the "hole" made is just wide enough for the antenna, so they can't push the drill/antenna any further. So they can't make holes any deeper than the given a quarter of wavelength rule.
That's what I said: the drill is a highly directional antenna. The undescribed mechanism is the radiation energy absorbed by the material which is being drilled. (Energy equals heat, among some other things.)
They can't move the drill forward without moving the (presumably non-conducting) chuck, or all their micropwave energy will radiate sideways, gently heating that which they do not want to heat and failing to heat that which they want to drill.
Yes, you're right about that. I first thought that the mechanism of drilling is as follows: heat the material with microwaves and when the material is sufficiently hot/soft, push the drill/antenna as deep as you can and repeat. The problem is that the "hole" made is just wide enough for the antenna, so they can't push the drill/antenna any further. So they can't make holes any deeper than the given a quarter of wavelength rule.
