( ( A ( radio ( frequency wave ) ) ) ( ( is transmitted ) . ) )
(ROOT (S (NP (DT A) (NN radio) (NN frequency) (NN wave)) (VP (VBZ is) (VP (VBN transmitted))) (. .)))
A radio frequency wave is transmitted.
(ROOT (S (NP (NNP Am) (NN radio) (NNS waves)) (VP (VBP exist) (PRT (RP in)) (NP (DT the) (ADJP (QP (CD 540) (TO to) (CD 1600))) (NN khz) (NN frequency) (NN range))) (. .)))