In this dissertation, a series of printed multiband antennas for slim mobile communication devices are presented. The study mainly focuses on how to effectively enhance the impedance bandwidth. With the equivalent LC matching circuit integrated in the antennas, wide impedance bandwidth can be obtained without increasing the size of the antennas. Note that the equivalent matching circuit can be formed by the coupling strip and the shorting strip to generate capacitance and inductance, respectively. In addition, the effects on the user's hand, head and whole body will be analyized. Also, the issue of the hearing aid compatibility will be discussed in this dissertation.

In this dissertation, a variety of novel mutiband WWAN loop antennas are presented. By designing proper coupled-fed mechanisms for the proposed loop antennas, the impedance bandwidth of the loop antenna can be greatly enhanced to achieve two wide operating bandwidths at antenna¡¦s lower and upper bands to easily cover GSM850/900/1800/1900/UMTS operation. With two wider operating bandwidths obtained, the tolerance of frequency detuning and the capability of bandwidth tuning of the loop antennas can be improved for practical applications. In addition, in order to find methods to meet the SAR and HAC criterions, the proposed small-size chip loop antenna studied in this dissertation which is suitable for both bar-type and folder-type mobile phone applications are simulated and analyzed for SAR and HAC issues.