Yes / A frequency tunable planar inverted F antenna (PIFA) is presented for use in the following bands: DCS, PCS, and UMTS. Initially, the tuning was achieved by placing a lumped capacitor, with values in the range of 1.5 to 4 pF, along the slot of the radiator. The final tuning circuit uses a varactor diode, and discrete lumped elements are fully integrated with the antenna. The antenna prototype is tunable over from 1850 MHz to 2200 MHz, with an associated volume of 21×13.5×5 mm3, making it suitable for potential integration in a commercial handset or mobile user terminal.

This thesis presents the analysis, design, and fabrication of a spherical inverted-F antenna (SIFA). The SIFA consists of a spherically conformal rectangular patch antenna recessed into a quarter section of a metallic sphere. The sphere acts as a ground plane, and a metal strip shorts the patch to the metallic sphere. The SIFA incorporates planar microstrip design into a conformal spherical geometry to better meet the design constraints for integrated wireless sensors. The SIFA extends a well-established technology into a new application space, including microsatellites, mobile sensor networks, and wireless biomedical implants. The complete SIFA design depends on several parameters, several of which parallel planar design variables. A modified transmission line model determines the antenna input impedance based on the sphere's inner and outer radii, the patch length and width, short length and width, and feed position. The SIFA can be tuned to the desired frequency band by choosing the proper outer radius, after which the antenna can be matched by tuning the short characteristics, patch dimensions, and feed position. The fabricated design was chosen to operate at the MICS band (402-405 MHz), a popular band for biomedically implanted devices. An initial design was constructed with Styrofoam (epsilon r approximately equal to 1) and copper tape. Simulation in HFSS corroborates that SIFA operation incorporates the MICS band, with resonant frequency of 404 MHz and 32 MHz (7.9%) bandwidth. The fabricated prototype performs similarly, with a resonant frequency of 407 MHz and 19 (4.7%) MHz bandwidth. Following fabrication, several modifications were implemented to miniaturize the SIFA and introduce additional functionality. Slot loading and dielectric coating were implemented to achieve SIFA miniaturization. Multiple elements were also introduced to achieve dual band operation and beam steering. A miniaturized SIFA was investigated in several biological media, and a lossy coating implemented to maintain impedance match in several different media, with the goal of retaining a matched impedance bandwidth in the MICS band.

This thesis proposes a variety of antenna designs suitable for modern of mobile products, such as mobile phones, PDAs and so forth, on both the 2G and 3G communication systems according to the mobile communication development. Based on the integration of monopole or planar inverted-F antenna with the system ground planes, multi-frequency, broadband, and high radiation efficiency can be achieved, which is very promising to be adapted into communication products. Furthermore, an antenna capable of WLAN and UWB is proposed for future wireless communication applications.

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.

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.

yes / A novel miniaturized planar double inverted-F antenna is presented. The antenna design is based on the electromagnetic coupling of two air dielectric PIFA antennas, combined with a broadband rectangular plate feed structure to achieve ultra-wideband characteristics. The computed and experimental impedance bandwidths show good agreement over an UWB frequency band from 3.1 GHz to 10.6 GHz for |S11| < -10dB. The antenna is electrically small, with size 0.31 x 0.16 x 0.09 wavelengths at 3.1 GHz and 1.06 x 0.55 x 0.31 wavelengths at 10.6 GHz. The simulated and measured gain and radiation patterns show acceptable agreement and confirm that the antenna has appropriate characteristics for short range wireless applications. / MSCRC

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.