directional antenna vs antenna

directional antenna and antenna both are nouns.

Word	Noun	Adjective	Verb	Adverb
directional antenna	Yes	No	No	No
antenna	Yes	No	No	No

As nouns, antenna is a hypernym of directional antenna; that is, antenna is a word with a broader meaning than directional antenna:

directional antenna: an antenna that transmits or receives signals only in a narrow angle
antenna: an electrical device that sends or receives radio or television signals

Other hypernyms of directional antenna include aerial, transmitting aerial.

directional antenna (noun)	antenna (noun)
an antenna that transmits or receives signals only in a narrow angle	one of a pair of mobile appendages on the head of e.g. insects and crustaceans; typically sensitive to touch and taste
	an electrical device that sends or receives radio or television signals
	sensitivity similar to that of a receptor organ