Miniaturized printed wire antennas in system in package were investigated for 2.4 GHz wireless communication systems. An inverted F antenna was proposed, and had a small area with 15 mm by 15 mm. The position of feed tap connected to the antenna arm greatly influenced the impedance of antenna, namely, it could adjust the position of feed tap to match the impedance to 50 ohm. The influences of chips and epoxy molding compounds on the impedance were also studied. Eventually, the inverted F antenna in package had a bandwidth and gain with almost 200 MHz and 2.8 dB, respectively, and could meet the demands of 2.4 GHz wireless communication.