- #1
yungman
- 5,755
- 292
The vector magnetic potential is given
[tex]\vec A=\frac{\mu I}{4\pi}\oint\frac{e^{-j\beta R_1}}{R_1}dl'[/tex]
After a few steps, the equation becomes:
[tex]\vec A=\frac{\mu I}{4\pi}e^{-j \beta R}\left[ (1+j\betaR)\oint\frac{dl'}{R_1}-j\beta\oint dl'\right][/tex]
The Book claim the second integral obviously vanishes!
I don't understand this. For a small loop, ##dl'=rd\phi##
[tex]\oint dl'=\int_0^{2\pi}rd\phi=2\pi r[/tex]
That is not zero by any stretch. Can anyone explain this?
thanks
[tex]\vec A=\frac{\mu I}{4\pi}\oint\frac{e^{-j\beta R_1}}{R_1}dl'[/tex]
After a few steps, the equation becomes:
[tex]\vec A=\frac{\mu I}{4\pi}e^{-j \beta R}\left[ (1+j\betaR)\oint\frac{dl'}{R_1}-j\beta\oint dl'\right][/tex]
The Book claim the second integral obviously vanishes!
I don't understand this. For a small loop, ##dl'=rd\phi##
[tex]\oint dl'=\int_0^{2\pi}rd\phi=2\pi r[/tex]
That is not zero by any stretch. Can anyone explain this?
thanks