( ( ( ( ( ( a ( radio operator ) ) ( is ( a person ) ) ) , ) and ) ( ( a ( radio frequency ) ) ( is ( an ( electromagnetic wave ) ) ) ) ) . )
(ROOT (S (S (NP (DT a) (NN radio) (NN operator)) (VP (VBZ is) (NP (DT a) (NN person)))) (, ,) (CC and) (S (NP (DT a) (NN radio) (NN frequency)) (VP (VBZ is) (NP (DT an) (JJ electromagnetic) (NN wave)))) (. .)))
a radio operator is a person, and a radio frequency is an electromagnetic wave.
(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))) (. .)))