The study in this thesis focuses on the DTV antennas for mobile applications. By using the novel techniques in the proposed antenna, the narrow-band problem and the radiation pattern of the conventional DTV antenna can be improved. In the first design, the antenna comprises two radiating arms. By adjusting the open gap between the ends of the two radiating arms, large impedance bandwidth can be obtained for DTV signal reception. In the second design, by integrating a coupling portion into the dipole antenna, the full-wavelength resonant mode can be excited successfully and combined with the half-wavelength mode to form a wide operating band. Finally, in the third design, a U-shaped feeding gap is embedded within the V-shaped antenna to excite the full-wavelength resonant mode. Additionally, the dipole antenna can radiate comparable E£X and E£c components, resulting in no nulls in the total-power radiation patterns in the horizontal and vertical planes.

A mobile phone antenna with a radiating coupling feed is presented. By using the radiating coupling feed, the conventional coupled-fed loop antenna and coupled-fed shorted monopole antenna can be efficiently incorporated into the antenna structure and respectively excite a wide band resonant mode to cover GSM850/900 and GSM1800/1900/UMTS/LTE2300/2500 for the seven-band operation. Besides, the antenna can be in compact integration with the extended ground plane such that more electronic components in the mobile phone can be accommodated in the practical applications. In order to study the near-field radiation characteristics of the antenna, SAR and HAC are also simulated and analyzed.

In this dissertation, a variety of multiband communication device antennas using the coupling-feed mechanism are presented. The coupling feed contributes additional capacitance to the antenna¡¦s input impedance which shows a high inductive component for the traditional case of using a direct feed. In the first and second antenna designs, with the coupling feed, the high input inductance of the antenna is effectively compensated. This behavior leads to a dual-resonance excitation for the lower band of the antenna. Two wide operating bands are achieved, allowing the antenna¡¦s lower and upper bands to easily cover GSM850/900 and GSM1800/1900/UMTS operation. For the last two antenna designs, owing to the coupling feed, the very large input impedance seen at antenna¡¦s lower band is greatly decreased and results in successful excitation of the one-eighth wavelength (£f/8) mode of the antenna. The specific absorption rate and hearing aid compatibility results for these mobile phone antennas are also analyzed. The effects of presence of the user¡¦s hand on the laptop computer antenna performance are also studied in this dissertation.