This paper proposes novel PIFA and monopole designs for dual-band or multi-band wireless communications, especially for mobile phones and CF (compact flash) card. The dual-frequency designs for mobile phone mainly utilize one or more metal branch strips to excite two resonant modes. By tuning the dimensions of branch strips, the ratio of the antenna¡¦s first two resonant frequencies can be achieved to be about 2.0, which makes it very promising for 900/1800 MHz operations. In addition, the broadband and quad-band (AMPS/GSM/DCS/PCS) designs for mobile phone application are also proposed. The broadband antenna design, unlike the above-mentioned dual-frequency designs for operating at two separate resonant modes, is more suitable to cover several nearby communication bands (DCS/PCS/UMTS/WLAN 2.45 GHz). The quad-band antenna design utilizes a £k-shape matching bridge to achieve a wider bandwidth both in lower and higher bands. For CF Card application, the triangular chip antenna having one longer and one shorter strip lines can generate the lower and higher modes covering the WLAN 2.4 and WLAN 5.2/5.8 GHz bands. All the antenna designs proposed are very promising to be concealed within the housing of the mobile phones or CF card.

In this thesis the study mainly focuses on the trends in development of present-day mobile phones and provides a promising alternative for integrating various elements inside mobile phones. With the presence of a small ground plane protruded from the main circuit board of a mobile phone, the proposed antenna design is substantially different from the configuration of feeding the conventional internal patch or planar inverted-F antenna (PIFA), and the proposed antenna can be placed in close proximity to the RF shielding case in the mobile phone, with very small effects on the antenna performances. Thus, more flexibility in the integration between an internal antenna and other associated elements inside a mobile phone can be obtained. In addition, by making use of the space inside the shorting cylinder of the internal PIFA, which can be treated as a shielding wall, the lens module of an embedded digital camera or other possible practical modules can easily fit in the cylinder to satisfy the trends in development of the miniaturized and multi-function mobile phones.

Three novel wideband antennas suitable for DTV (Digital Television) signal reception in the 470 ~ 806 MHz band for Portable Media Playrer (PMP) applications are presented in this thesis. The antennas include a novel broadband planar monopole antenna in Chpater 2, a novel low-profile planar inverted-U monopole antenna in Chpater 3, and a novel internal planar inverted-F antenna in Chpater 4. These antennas all have wide impedance bandwidths, good radiation efficiencies, and good radiation patterns. In addition, we propose a one-layer simplified hand model for achieving efficient and reliable simulation study for PMP antennas. The studied antenna in Chapter 2 is selected to be the example to study the user¡¦s hand effect on the antenna for PMP application.

A six-band antenna design for the mobile phone is presented. The required bandwidth for DTV/GSM850/900/DCS/PCS/UMTS operation is achieved by using two antennas. For DTV/GSM850/900 operation, we propose a novel antenna by using the concept of the dipole antenna and an internal matching portion to excite the half- and one-wavelength resonant modes of the antenna. With the internal matching portion, the frequency ratio of the two resonant modes can be controlled, thereby making the two resonant modes formed into a very wide operating band. For DCS/PCS/UMTS operation, a novel monopole slot antenna is used. The lower-edge frequency of the slot antenna depends on its length and the required bandwidth can be achieved by adjusting its tuning section. Effects of casing and human body on the proposed mobile phone antenna are also discussed. It is found that the radiation efficiency of DTV/GSM bands is larger than that of DCS/PCS/UMTS bands in this design. However, overall the operating bands, the antenna performances are greatly affected when the human effects are taken into considerations.

Two novel antenna designs for mobile handsets are proposed in this thesis. With a helix loading, an inverted-L monopole antenna capable of generating two resonances at about 900 and 1850 MHz is first presented. The operating bandwidths obtained cover the required bandwidths of the GSM/DCS/PCS bands. Besides, an internal mobile handset antenna comprising a PIFA and a PILA, which are, respectively, designed for covering the GSM and DCS/PCS bands is also presented. The PIFA and PILA together occupy a compact volume of 7.2 ¡Ñ 20 ¡Ñ 40 mm3, and are suitable to be built-in within the housing of a mobile handset.

In this thesis, three small-size internal multiband antennas for laptop computer application for different wireless communication systems are proposed. In the first design, the coupling feed is incorporated to the planar inverted-F antenna to achieve a dual-resonance excitation in the lower band such that the obtained bandwidths can easily cover GSM850/900/DCS/PCS/UMTS operation. The effect of the user¡¦s hand on the antenna is also studied. In the second design, we introduce the T-shaped coupling feed used in the PIFA for successful excitation of two wide operating bands to cover WLAN operation in the 2.4 GHz band and 5.2/5.8 GHz band, and the size reduction is even larger than 50%. Finally, a multiband monopole antenna with a band-notching slit is proposed. By embedding the slit of length about a quarter-wavelength at about 4 GHz, a band-notching characteristic is obtained, which leads to an additional resonance at about 3.5 GHz. Hence, three wide operating bands for covering all the desired operating bands of WLAN/WiMAX systems are achieved for the proposed antenna.

No / A novel miniaturized planar inverted F-L antenna assembly is considered for UWB radio operations. The antenna design utilizes the electromagnetic coupling between an air dielectric planar inverted-F antenna (PIFA) and a parasitic planar inverted-L (PIL) element, with broadband feeding from a rectangular plate. To improve the functionality of the channel, a simple notch filter has been introduced through a local modification to the broadband feed plate, this takes the form of a simple slotted rectangular spiral resonator which is etched directly onto the plate. This allows the proposed antenna to maintain its full band UWB coverage, with the HYPERLAN/2 band centered at 5.35 GHz to be effectively rejected over the sub-band 5.15–5.725 GHz, without the need for substantial re-optimization of its principal structure parameters. The impedance bandwidth operates over the full UWB band, with VSWR better than 2, this performance is not degraded by the presence of the band rejection. The observed gains, radiation patterns, and group delay confirm that the antenna has appropriate characteristics for short range wireless applications.

In recent years, the demand for compact handheld communication devices has grown significantly. Devices having internal antennas have appeared to fill this need. Antenna size is a major factor that limits device miniaturization. In the past few years, new designs based on the microstrip antennas (MSA) and planar inverted-F antennas have been used for handheld wireless devices because these antennas have low-profile geometry and can be embedded into the devices. New wireless applications requiring operation in more than one frequency band are emerging. Dual-band and tri-band phones have gained popularity because of the multiple frequency bands used for wireless applications. One prominent application is to include bluetooth, operating band at 2.4 GHz, for short-range wireless use. This thesis examines two antennas that are potential candidates for small and low-profile structures: microstrip antennas and planar inverted-F antennas. Two techniques for widening the antenna impedance bandwidth are examined by adding parasitic elements. Reducing antenna size generally degrades antenna performance. It is therefore important to also examine the fundamental limits and parameter tradeoffs involved in size reduction. In the handheld environment, antennas are mounted on a small ground plane. Ground plane size effects on antennas are investigated and the results from a thorough numerical study on the performance of a PIFA with various ground planes sizes and shapes is reported. Finally, a new wideband compact PIFA antenna (WC-PIFA) is proposed. Preliminary work is presented along with numerical and experimental results for various environments such as free space, plastic casing, and the proximity of a hand. This new antenna covers frequencies from 1700 MHz to 2500 MHz, which basically include the following operating bands: DCS-1800m PCS-1900, IMT-2000, ISM, and Bluetooth. / Master of Science

This paper proposes novel antenna designs for cellular phones and WLAN (Wireless LAN) applications. For cellular phones, a dual- frequency PIFA (Planar Inverted-F Antenna) loaded with a chip inductor is constructed. In order to decrease the construction cost, PIFAs without a loading chip inductor for GMS/DCS phones are devised. Besides, a PIFA-monopole antenna for GSM/DCS/PCS is also proposed. For WLAN application, a dual-band PIFA for 2.4/5.8 GHz and a dual-band integrated monopole antenna for 2.4/5.2 GHz are shown. Finally, a novel metal-plate WLAN antenna, having a simple structure and being easy to construct with low cost, is presented.

A variety of internal mobile phone antennas with a coupling feed are proposed. The antennas are suitable to be embedded in the mobile communication devices. At first, the coupling feed is incorporated to the conventional dual-band PIFA (planar inverted-F antenna) to achieve a dual-resonance excitation at about 900 MHz such that the obtained bandwidths can easily cover GSM850, GSM900, DCS and PCS operations. Then, the coupling feed is further applied to the PIFA with a single resonant path close to about one-eighth wavelength at 900 MHz. In this design, the large input impedance at 900 and 1900 MHz can be greatly decreased to allow the PIFA to generate two operating bands at about 900 and 1900 MHz to cover GSM900, DCS, PCS and UMTS operations. Finally, a compact quad-band folder-type mobile phone antenna with a coupling feed is proposed. The one-eighth wavelength mode can be excited, and the obtained bandwidths cover GSM850, GSM900, DCS and PCS operations.