短波 is read as たんぱ (tampa) and means short wave.
たんぱ
tampa
たんぱじゅしんき
short-wave receiver
たんぱほうそう
short-wave broadcasting
たんか
tanka
たんざく
thin rectangle
たんだい
junior college
たんき
short-term
たんきだいがく
たんしょ
defect
みじかい
brief
short temper
みじかめ
shortish
たんじかん
short time