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I'm not an electrical engineer, however I suspect that RF is expensive in terms of energy. So battery issues, and solar energy conversion efficiency I expect. A

I'm not an electrical engineer, however I suspect that RF is expensive in terms of energy. So battery issues, and solar energy conversion efficiency I expect. And these days the phone has evolved into a fully blown computer, so yeah - energy requirements. But those little credit card solar calculators were cool, I remember the one I had well... There are some amazingly small phones these days approaching that form factor... google worlds smallest phones etc. Anyhow - maybe a real engineer can comment further?

ghaff 6y ago
You also need at least a little bit of analog electronics (mic and speaker). Assume you can power it with a solar panel that covers the back of the phone though. (I'm not sure you can for reasonable talk times.) What now? You can't hold the phone in your hand because you're covering the solar panel. You're probably also going to be a little bit thicker than a credit card because of the audio.