( It ( ( 's ( ( a type ) ( of ( ( low-frequency ( radio wave ) ) ( which ( is ( made ( of protons ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (PRP It)) (VP (VBZ 's) (NP (NP (DT a) (NN type)) (PP (IN of) (NP (NP (JJ low-frequency) (NN radio) (NN wave)) (SBAR (WHNP (WDT which)) (S (VP (VBZ is) (VP (VBN made) (PP (IN of) (NP (NNS protons))))))))))) (. .)))
It's a type of low-frequency radio wave which is made of protons.
(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))) (. .)))