An 'antenna' is:

Options

A. is resistive above its resonant frequency
B. is resistive at resonant frequency
C. allows signals to pass `x_(L)=x_(C)`
D. allows signals to pass when `x_(L)cancel=x_(C)`

Explanation

Inpedence of circuit is given by
`Z=sqrt(R^(2)+(X_(L)-X_(C))^(2))`
Antenna works at resonance, for resonance
`X_(L)=X_(C)` i.e. `omega_(r)L(1)/(omega_(r)C) therefore v_(r)=(1)/(2pisqrt(LC))`
which is resonant frequency, when
`X_(L)=X_(C) Z=R`. ltbgt So antenna is resistive at resonant frequency.