# Antenna Problem

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1. May 19, 2017

### JordanD

Hello all,
I have a problem with a typical style of problem I seem to always struggle with. Just to clear this up, I am studying for my comprehensive exams later this summer. So I am going through past problems to bone up on the last two years of grad school. At which point I came across this type of problem that I see to always struggle with so I am here to gain some insight on how to do these problems and what is being asked of me. The question goes as such:

"Qualitatively estimate the frequency and power of electromagnetic radiation emitted by a cellular phone during a typical phone call."

Now there are a few things I know and a few things that are given on the exam:

I know P(r)=I(4πr2) and I=1/2ε0cE2

I am also given the equation for the "Time averaged power radiated per unit solid angle" (See Jackson eqn 9.56) with Z0=377Ω

Now I have given you everything I have been given, so my question stands. Obviously there should be enough info here seeing as this is a past comprehensive exam, but I don't have the foggiest idea how to start. I strongly feel like I don't have enough info to go forward with, but I know I am wrong. Any insight or advice is strongly appreciated.

2. May 19, 2017

### Staff: Mentor

You have done nothing to answer this question. Please show us more work.

What frequencies are used for typical cell phones? What power do typical cell phones transmit? Please show more effort.

Last edited: May 19, 2017