Novel chip antennas having an attractive EMC¡]Electromagnetic Compatibility¡^property for WLAN¡]Wireless Local Area Network¡^operations are demonstrated in this thesis. With the EMC property, the proposed antennas are suitable to be applied as internal antennas in mobile communication devices, such as the smart phones or PDA¡]Personal Digital Assistant¡^phones. With the antenna ground portion functioning as a new ground structure, the EM fringing fields in the surrounding region of the proposed antennas are greatly reduced to be negligible. When the possible RF shielding metal case or other electronic components are placed close to the proposed antennas, the antenna performances are almost unaffected. In other words, the isolation distance between the antenna and the nearby components will be no long required. This can lead to a compact integration of the proposed antennas with the nearby components in mobile communication devices. Details of the measured and simulated results of the proposed EMC chip antennas are presented and discussed.