Planar inverted F shaped antenna, and method for adjusting input impedance

The antenna unit includes antenna prepared from sheet metal, shell body, and coaxial cable. The antenna includes radiation sect, grounding sect, and impedance matching sect with impedance matching space. The coaxial cable includes inner core connected to the radiation sect, and braid conductor connected to the grounding sect. The antenna unit also includes metal foil located inside the impedance matching space. The metal foil connected to the impedance matching sect is in use for adjusting input impedance. The method for adjusting input impedance includes steps: (1) selecting antenna and shell utilized inside notebook computer; (2) sticking metal foil to certain area inside shell; thus, after antenna is assembled to shell, the said area is corresponding to the impedance matching space; (3) assembling antenna to shell to make metal foil contact to the impedance matching sect. Advantages are: without need of change dies for antenna, and reducing cost for authenticating antenna.