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

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.

The beginning of the 21 st century is characterised, among others, by the evolution in telecommunications. The rapid growth of mobile communications and the variety of applications proposed for the third generation (3G) systems require long operation time, low weight and cost for terminals, as well as improved link quality. For this reason a good efficiency and low profile antennas with low absorption losses by the user are desirable. The Planar Inverted-F Antenna (PIFA) is shown to result into low SAR values and high efficiency when operating in the proximity of the user. Despite these advantages, PIFA is also characterised by narrow bandwidth that limits its practical use. The first part of this work is dedicated to the measurements and evaluation of the radiation characteristics of the PIFA and other wire antennas both in the near and far fields. In addition, novel methods of PIFA tuning are presented. These include the repositioning of the shorting pin and modification of its capacitance. By using these techniques, the effective bandwidth of the PIFA can be increased to satisfy the GSM900 and DCS 1800 system bandwidth requirements. Dual-band and electronically tuned PIFA prototypes are also included. The effects of the handset size on the mass averaged Specific Absorption Rate (SAR), and antenna efficiency are investigated. The appropriate choice of handset can result in up to 30%-reduced peak SAR. The computed SAR values from PIFA are compared with those resulting from the use of a handset equipped with quarter wavelength monopole antenna. A new measure referred to as the 3dB SAR volume is proposed. This measure provides better understanding of the absorbed power distribution in the operator's head. Results obtained in the course of study show that low profile handset antennas, such as the PIFA, present in addition to dual resonance and low reflection losses, reduced SAR values, high efficiency and low 3dB SAR volume. Finally, SAR and 3dB SAR volume values from simulations on 5- and 10- years old child head models are compared with their equivalents for adult models from which appropriate conclusions are drawn.

In this thesis, the studies mainly focus on recent trends in novel MIMO antennas for indoor wireless communication system. Firstly, we propose a novel MIMO antenna for access-point application. This proposed antenna can reduce the lateral length of the conventional access-point antenna for MIMO application. Then, we present MIMO antenna designs for mobile devices such as PDA phones and laptop computers. Although these two devices are of different configurations, the PIFAs are applicable in these two devices, and their design rules are basically the same. Thus, for this study, the design consideration of the MIMO antenna will focus on S-parameter analysis. Detailed antenna designs and experimental results are presented and discussed in this thesis.

The main objective of this research is to design, model and implement several antenna geometries using electromagnetic band gap (EBG) material and a defected ground plane. Several antenna applications are addressed with the aim of improving performance, particularly the mutual coupling between the elements. The EBG structures have the unique capability to prevent or assist the propagation of electromagnetic waves in a specific band of frequencies, and have been incorporated here in antenna structures to improve patterns and reduce mutual coupling in multielement arrays. A neutralization technique and defected ground plane structures have also been investigated as alternative approaches, and may be more practical in real applications. A new Uni-planar Compact EBG (UC-EBG) formed from a compact unit cell was presented, giving a stop band in the 2.4 GHz WLAN range. Dual band forms of the neutralization and defected ground plane techniques have also been developed and measured. The recorded results for all antenna configurations show good improvement in terms of the mutual coupling effect. The MIMO antenna performance with EBG, neutralization and defected ground of several wireless communication applications were analysed and evaluated. The correlation coefficient, total active reflection coefficient (TARC), channel capacity and capacity loss of the array antenna were computed and the results compared to measurements with good agreement. In addition, a computational method combining Genetic Algorithm (GA) with surface meshing code for the analysis of a 2×2 antenna arrays on EBG was developed. Here the impedance matrix resulting from the meshing analysis is manipulated by the GA process in order to find the optimal antenna and EBG operated at 2.4 GHz with the goal of targeting a specific fitness function. Furthermore, an investigation of GA on 2×2 printed slot on DGS was also done.

Abstract In this thesis, bandwidth (BW) enhanced antennas for mobile terminals and multilayer ceramic packages are presented. The thesis is divided into two parts. In the first part, electrically frequency-tunable mobile terminal antennas have been studied. The first three antennas presented were of a dual-band planar inverted-F type (PIFA) and were tuned to operate in frequency bands appropriate to the GSM850 (824–894 MHz), GSM900 (880–960 MHz), GSM1800 (1710–1880 MHz), GSM1900 (1850–1990 MHz) and UMTS (1920–2170 MHz) cellular telecommunication standards with RF PIN diode switches. The first antenna utilized a frequency-tuning method developed in this thesis. The method was based on an integration of the tuning circuitry into the antenna. The tuning of the second antenna was based on a switchable parasitic antenna element. By combining the two frequency-tuning approaches, a third PIFA could be switched to operate in eight frequency bands. The planar monopole antennas researched were varactor-tunable for digital television signal reception (470–702 MHz) and RF PIN diode switchable dual-band antenna for operation at four cellular bands. The key advantage of the former antenna was a compact size (0.7 cm3), while for the latter one, a tuning circuit was implemented without using separate DC wiring for controlling the switch component. The second part of the thesis is devoted to multilayer ceramic package integrated microwave antennas. In the beginning, the use of a laser micro-machined embedded air cavity was proposed to enable antenna size to impedance bandwidth (BW) trade-off for a microwave microstrip in a multilayer monolithic ceramic media. It was shown that the BW of a 10 GHz antenna fabricated on a low temperature co-fired ceramic (LTCC) substrate could be doubled with this technique. Next, the implementation of a compact surface mountable LTCC antenna package operating near 10 GHz was described. The package was composed of a BW optimized stacked patch microstrip antenna and a wide-band vertical ball grid array (BGA)-via interconnection. Along with the electrical performance optimization, an accurate circuit model describing the antenna structure was presented. Finally, the use of low-sintering temperature non-linear dielectric Barium Strontium Titanate (BST) thick films was demonstrated in a folded slot antenna operating at 3 GHz and frequency-tuned with an integrated BST varactor.

The main objective of this research is to design, model and implement several antenna geometries using electromagnetic band gap (EBG) material and a defected ground plane. Several antenna applications are addressed with the aim of improving performance, particularly the mutual coupling between the elements. The EBG structures have the unique capability to prevent or assist the propagation of electromagnetic waves in a specific band of frequencies, and have been incorporated here in antenna structures to improve patterns and reduce mutual coupling in multielement arrays. A neutralization technique and defected ground plane structures have also been investigated as alternative approaches, and may be more practical in real applications. A new Uni-planar Compact EBG (UC-EBG) formed from a compact unit cell was presented, giving a stop band in the 2.4 GHz WLAN range. Dual band forms of the neutralization and defected ground plane techniques have also been developed and measured. The recorded results for all antenna configurations show good improvement in terms of the mutual coupling effect. The MIMO antenna performance with EBG, neutralization and defected ground of several wireless communication applications were analysed and evaluated. The correlation coefficient, total active reflection coefficient (TARC), channel capacity and capacity loss of the array antenna were computed and the results compared to measurements with good agreement. In addition, a computational method combining Genetic Algorithm (GA) with surface meshing code for the analysis of a 2×2 antenna arrays on EBG was developed. Here the impedance matrix resulting from the meshing analysis is manipulated by the GA process in order to find the optimal antenna and EBG operated at 2.4 GHz with the goal of targeting a specific fitness function. Furthermore, an investigation of GA on 2×2 printed slot on DGS was also done. / Ministry of Higher Education Malaysia and Universiti Tun Hussein Onn Malaysia (UTHM)

The rapidly growing demand for UWB as high data rates wireless communications technology, since the Federal Communications Commission (FCC) allocated the bandwidth of UWB from 3.1GHz to 10.6 GHz. Antenna also plays an essential role in UWB system. However, there are some difficulties in designing UWB antenna as compared to narrowband antenna. The primary requirement of UWB antennas is be able to operate over frequencies released by the FCC. Moreover, the satisfaction of radiation properties and good time domain performance over the entire frequency range are also necessary. In this thesis, designing and analysing printed crescent shape monopole antenna, Planar Inverted F-L Antenna (PIFLA) and Planar Inverted FF Antenna (PIFFA) are focused. A Planar Inverted FF Antenna (PIFFA) can be created to reduce the potential for interference between a UWB system and other communications protocols by using spiral slot. The antennas exhibits broadside directional pattern. The performances such as return loss, radiation pattern and current distribution of the UWB antennas are extensively investigated and carried out. All the results have been demonstrated using simulation and experimentally whereby all results satisfy the performance under - 10dB point in the bandwidth of UWB. In addition the miniaturization of MIMO/diversity Planar Inverted-F antenna (PIFA) which is suitable for pattern diversity in UWB applications is presented. This antenna assembly is formed by two identical PIFAs, a T-shaped decoupling structure which connects the two PIFAs and a finite ground plane with a total compact envelope dimension of 50 x 90 x 7.5mm³. The radiation performance of the proposed MIMO antenna was quite encouraging and provided an acceptable agreement between the computed and measured envelope correlation coefficient and channel capacity loss.