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.

藉由研究無線通信產業標準的制訂過程與主流標準的形成機制，本研究探討過去有關影響產業標準建立的文獻與個案，提出系統發展過程中，各影響因素扮演的角色與提供的功能，以瞭解在無線通信產業中，影響一標準脫穎而出成為市場主流的關鍵因素。本研究主要的研究發現如下： 一、政府的政策對標準後續發展相當重要，若政府態度是採開放競爭，則將在境內形成多種標準競爭而耗掉大部分能量，未來在標準向外推展上較吃虧。反之政府若能主導統一標準，常能使相關資源更集中焦點來發展單一標準，未來對外推展上較能成功。 二、協會能否發揮協商能力，使各業者提出之標準能相結合，是主流標準形成之關鍵之一，協會若能使各業者放棄成見，取得共識形成單一標準將有助於標準之發展。 三、對標準主導者而言，若能成為主流標準確實擁有很多潛在利益，為爭取標準的支持度，便會有很多遊說及策略聯盟產生，若能取得越多成員支持，常較能形成主流標準，因此標準擁有者若能降低權利金門檻，甚至將其免費授權並公開架構，標準成為市場主流之成長速度將會加快。但若成員過於複雜也容易阻礙標準演進的進度。 四、第三代行動電話的應用以多媒體為主，這是相當革命性的嚐試，故能否找到消費者公認的殺手級應用服務（killer application）成為成敗關鍵要素之一。 五、標準形成之發源地需有足夠的經濟規模量的支持，才能累積足夠資源向境外擴展。 六、標準形成在發酵期必須取得單一標準共識，在漸進變化期於境內快速建立成功經驗，並順利將成功複製於境外地區，這個模式較能成功成為主流標準。另在建立標準時需有明確的願景與目標、具國際化的規格設計，才可減少在對外擴展時之障礙。 / This thesis is intended to make explicit the roles played and functions provided by the various factors in the process of system development by means of an investigation of the process of the formation of a wireless communications standard and the mechanism that makes it a dominant. By studying the documents and cases on the factors affecting the establishment of a standard, we have come to recognize six fundamentals that make it stand out as a dominant. These six fundamentals are summarized as follows: 1. The policy made by the government plays an essential part in the further development of the formation of a given standard. If the government adopts an attitude of open competition, then lots of related resources will be wasted on the keen competition between vying forces in the local market, which is, in turn, detrimental to outward expansion. On the contrary, if the government integrates the related resources and helps form a unitary standard, the standard may succeed in opening other markets. 2. The Association is also an important positive contributor in the process of the formation of a unitary standard. The Association should do its best to mediate between each vying standard to reach an agreement and adopt a unitary standard, which is definitely instrumental in the further development. 3. For those who want to direct the formation of a standard and get the tremendous potential profits from it, they will do a lot of lobbying and form strategic alliances to attract more supports for the standard. When succeeding in doing so, the owners of the unitary standard can speed up the growth of its market by lowering the royalty and license limit, or even by opening its architecture with a free authorization. 4. The application of the third-generation cellular phones features multi-media, which is a considerably revolutionary attempt. Therefore, the success of it depends on whether the standard can come up with a killer application that appeals to consumers. 5. The local market from which the standard originates should be big enough to support it, so the standard can stand firm on the strong basis and reach out for other markets. 6. The formation of a standard should be based on an agreement of a unitary standard at the ferment stage. And at the transition stage, it should build up a successful experience as soon as possible in the local market and then successfully duplicate the model in the international ones. Besides, a definite goal and a clear vision as well as internationalized regulations and designs all contribute to lifting the barriers in its expanding outwards.

No description available.

The main objectives of this research are to investigate and design low profile antennas for mobile handsets applications using the balanced concept. These antennas are considered to cover a wide range of wireless standards such as: DCS (1710¿1880 MHz), PCS (1850¿1990 MHz), UMTS (1920¿2170 MHz), WLAN (2400¿2500 MHz and 5000 ¿ 5800 MHz) and UWB frequency bands. Various antennas are implemented based on built-in planar dipole with a folded arm structure. The performance of several designed antennas in terms of input return loss, radiation patterns, radiation efficiency and power gain are presented and several remarkable results are obtained. The measurements confirm the theoretical design concept and show reasonable agreement with computations. The stability performance of the proposed antenna is also evaluated by analysing the current distribution on the mobile phone ground plane. The specific absorption rate (SAR) performance of the antenna is also studied experimentally by measuring antenna near field exposure. The measurement results are correlated with the calculated ones. A new dual-band balanced antenna using coplanar waveguide structure is also proposed, discussed and tested; this is intended to eliminate the balanced feed network. The predicted and measured results show good agreement, confirming good impedance bandwidth characteristics and excellent dual-band performance. In addition, a hybrid method to model the human body interaction with a dual band balanced antenna structure covering the 2.4 GHz and 5.2 GHz bands is presented. Results for several test cases of antenna locations on the body are presented and discussed. The near and far fields were incorporated to provide a full understanding of the impact on human tissue. The cumulative distribution function of the radiation efficiency and absorbed power are also evaluated. / UK Engineering and Physical Sciences Research Council (EPSRC)

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 ¿ 90 ¿ 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. / General Secretariat of Education and Scientific Research Libya

General Secretariat of Education and Scientific Research, Libya. / The only available copy is the print version kept in the J.B.Priestley Library for reference.

Multiple-Input-Multiple-Output (MIMO) antenna technology refers to an antenna with multiple radiators at both transmitter and receiver ends. It is designed to increase the data rate in wireless communication systems by achieving multiple channels occupying the same bandwidth in a multipath environment. The main drawback associated with this technology is the coupling between the radiating elements. A MIMO antenna system merely acts as an antenna array if the coupling between the radiating elements is high. For this reason, strong decoupling between the radiating elements should be achieved, in order to utilize the benefits of MIMO technology. The main objectives of this thesis are to investigate and implement several printed MIMO antenna geometries with integrated decoupling approaches for WLAN, WiMAX, and 5G applications. The characteristics of MIMO antenna performance have been reported in terms of scattering parameters, envelope correlation coefficient (ECC), total active reflection coefficient (TARC), channel capacity loss (CCL), diversity gain (DG), antenna efficiency, antenna peak gain and antenna radiation patterns. Three new 2×2 MIMO array antennas are proposed, covering dual and multiple spectrum bandwidths for WLAN (2.4/5.2/5.8 GHz) and WiMAX (3.5 GHz) applications. These designs employ a combination of DGS and neutralization line methods to reduce the coupling caused by the surface current in the ground plane and between the radiating antenna elements. The minimum achieved isolation between the MIMO antennas is found to be better than 15 dB and in some bands exceeds 30 dB. The matching impedance is improved and the correlation coefficient values achieved for all three antennas are very low. In addition, the diversity gains over all spectrum bands are very close to the ideal value (DG = 10 dB). The forth proposed MIMO antenna is a compact dual-band MIMO antenna operating at WLAN bands (2.4/5.2/5.8 GHz). The antenna structure consists of two concentric double square rings radiating elements printed symmetrically. A new method is applied which combines the defected ground structure (DGS) decoupling method with five parasitic elements to reduce the coupling between the radiating antennas in the two required bands. A metamaterial-based isolation enhancement structure is investigated in the fifth proposed MIMO antenna design. This MIMO antenna consists of two dual-band arc-shaped radiating elements working in WLAN and Sub-6 GHz 5th generation (5G) bands. The antenna placement and orientation decoupling method is applied to improve the isolation in the second band while four split-ring resonators (SRRs) are added between the radiating elements to enhance the isolation in the first band. All the designs presented in this thesis have been fabricated and measured, with the simulated and measured results agreeing well in most cases. / Higher Committee for Education Development in Iraq (HCED)

The main objectives of this research are to investigate and design low profile antennas for mobile handsets applications using the balanced concept. These antennas are considered to cover a wide range of wireless standards such as: DCS (1710-1880 MHz), PCS (1850-1990 MHz), UMTS (1920-2170 MHz), WLAN (2400-2500 MHz and 5000-5800 MHz) and UWB frequency bands. Various antennas are implemented based on built-in planar dipole with a folded arm structure. The performance of several designed antennas in terms of input return loss, radiation patterns, radiation efficiency and power gain are presented and several remarkable results are obtained. The measurements confirm the theoretical design concept and show reasonable agreement with computations. The stability performance of the proposed antenna is also evaluated by analysing the current distribution on the mobile phone ground plane. The specific absorption rate (SAR) performance of the antenna is also studied experimentally by measuring antenna near field exposure. The measurement results are correlated with the calculated ones. A new dual-band balanced antenna using coplanar waveguide structure is also proposed, discussed and tested; this is intended to eliminate the balanced feed network. The predicted and measured results show good agreement, confirming good impedance bandwidth characteristics and excellent dual-band performance. In addition, a hybrid method to model the human body interaction with a dual band balanced antenna structure covering the 2.4 GHz and 5.2 GHz bands is presented. Results for several test cases of antenna locations on the body are presented and discussed. The near and far fields were incorporated to provide a full understanding of the impact on human tissue. The cumulative distribution function of the radiation efficiency and absorbed power are also evaluated.