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Comment by Perceval | Hacker News Reader

>After using so much aluminum in recent hardware designs, it’s interesting that they’re using stainless steel for the iPhone 4.

I wonder if this is related to the steel frame serving as the iPhone's antenna. Would steel be a better material than aluminum for this purpose?

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Al has higher conductivity than SS. I'd have to crunch numbers to see if it would make that much difference at cell phone frequencies (power budget). At 60 Hz, ACSR has most of the current in the Al not the steel from the skin effect.

SS has the advantage of strength over Al.

Possibly a SS exterior with Al inside.

edit: I cheated and glanced at the ARRL Handbook (2005) page 20.7 "The strongest wire suitable for antenna service is copperclad steel, also known as copperweld. The copper coating is necessary for RF service because steel is a relatively poor conductor."

Based on that I suspect a better conductor inside the SS or as part of the SS.

Further edit: using google, there are SS Yagi antennas so that is nothing new, not sure about other antenna types at this time. If Apple used SS and made a better antenna (larger?) then it might use less power than a smaller antenna using a better conductor.

last edit: SS whip antennas are also available, such that the material choice probably is not that big of deal as much as the design of the antenna itself.

Forged steel is much harder than anodized aluminum. My 1st gen aluminum phone got beat up and deformed, this should be much better. Also interesting is the incredible strength and toughness of the glass they showed getting deformed in the bend tester. Apple has replaced many of my iPhones, but I bet this one will be hard to break and they will lose a lot less money.

It's likely that steel is a better antenna but also it's probably stronger than aluminum. Their videos says they've made a special stainless steel that's even stronger than regular stainless steel. It'll also help for the stronger part of the phone to be the edges in case people drop their phone.

I wonder what the specs on the strength of this 'new stainless steel' are. I highly doubt that Apple is now pioneering new innovations in the realm of metallurgy "just to bring you a better iPhone," though their marketing would probably have you believe otherwise.

"Strength" of a metal is always a tweaked compromise of hardness and toughness. It could be that their steel is formulated specially for the particular structure of the iPhone 4. This wouldn't be a new pioneering branch of metallurgy, though it could be spun like that by marketdroids.

Agreed, drop a little more carbon into the steel and you've got your own new stainless steel that for all intensive purposes is probably identical to 3,000 types of steel already on the market by different producers globally.

Steel is steel, they probably researched the steel that works best as an antenna whilst not compromising the physical strength of the unit (for instance, you don't want the metal case to be the thing most likely to shatter on the device).

> intensive purposes

I love that eggcorn. It's "intents and purposes", btw.

  they've made a special stainless steel that's even stronger...

They've discovered Rearden Metal[1]! The only question now is who will be Dagny Taggart to Job's Hank Rearden.

[1] http://en.wikipedia.org/wiki/Atlas_Shrugged#Plot_summary

Does that mean that "Jony" Ive is Galt?

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