Yes / This paper presents a circular polarization reconfigurable antenna for 5G applications, which is compact in size and has good axial ratio and frequency response. The proposed microstrip antenna is designed on a FR-4 substrate with a relative dielectric constant of 4.3 and has a maximum size of 30×30 mm2 with 50 Ω coaxial probe feeding. This design has two PIN diode switches controlling reconfiguration between right hand circular polarization (RHCP) and left hand circular polarization (LHCP). To achieve reconfigurability, a C-slot rectangular patch antenna with truncated corner techniques is employed by cutting off two corners on the radiating patch. The proposed antenna has been simulated using CST microwave studio software: it has 3.35-3.77 GHz and 3.4-3.72 GHz bands for both states of reconfiguration, and each is suitable for 5G applications with a good axial ratio of less than 1.8 dB and good gain of 4.8 dB for both modes of operation. / Innovation programme under grant agreement H2020-MSCA-ITN-2016 SECRET-722424, UK Engineering and Physical Sciences Research Council (EPSRC) under grant EP/E022936/1.

The bandwidth-enhancement characteristics of slot-loaded rectangular microstrip antennas constructed on a thin microwave substrate have been investigated in this dissertation. The primary design process about this topic is demonstrated. Firstly, a new antenna design idea is provided from pre-determined antenna design specifications or obtained antenna performances from the previous antenna design, which lead to a novel antenna configuration. From the results of the simulation software IE3DTM, the characteristics of this new antenna configuration are obtained and compared with the experimental results. The antenna configuration is also modified to achieve a final optimal design from the comparison results. The study of the single-feed dual-frequency rectangular microstrip antenna with a pair of bent slots is first presented. By embedding properly-designed slots on a rectangular microstrip patch, the impedance characteristics of this antenna design have been effectively changed to exhibit dual-resonant behavior, which result in the excitation of two adjacent resonant modes with similar radiation characteristics. Furthermore, the two resonant modes can be excited at frequencies very close to each other to form a wider operating bandwidth by embedding additional perturbation slots. Four successful antenna designs with different embedded-slot shapes for bandwidth enhancement have been implemented and discussed in this dissertation.

Novel broadband designs of patch antennas with an air substrate have been proposed in this dissertation. In the dual-frequency design, the study of single-fed dual-frequency microstrip antenna with a V-shaped slot has been first presented. As for the broadband patch antenna design, antennas with a U-shaped slot or a pair of wide slits can have an operating bandwidth more than 2.0 times that of a conventional one at a given operating frequency. The antenna bandwidth of then can be enhanced about 25%. In the designs of reducing cross-polarization, by using dual capacitive feeds with equal input powers, but with a 180¢X-phase shift, The cross-polarization radiation can be reduce about 10 to 15dB in the H-plane. Finally, A broadband shorted patch antenna fed by an aperture-coupled feed with an H-shaped coupling slot is proposed. By using an air substrate of thickness about 0.07 free-space wavelength of the center operating frequency, the proposed antenna can have an impedance bandwidth of about 26.2%. And the antenna design reduced the antenna size to be 40%~50%of the simple case.

Les antennes microruban et en particulier l’antenne microruban rectangulaire sont étudiées et utilisées depuis plusieurs dizaines d’années.<p>Comme pour toute antenne, il est important de disposer pour ces antennes d’un modèle analytique qui permette une bonne compréhension du fonctionnement et fournisse de manière rapide des valeurs pour les principaux paramètres (fréquence de travail, impédance, gain, rendement et bande passante).<p>Au fil des ans, deux modèles, chacun comprenant de nombreuses variantes, ont été développés :le modèle dit « de la ligne de transmission » et le modèle dit « de la cavité ». Ces modèles sont soit peu rigoureux, soit complexes et donnent souvent des résultats assez éloignés de la réalité.<p>L’objectif de ce travail est double :définir un modèle qui soit d’une part aussi simple et direct que possible et d’autre part aussi précis que possible.<p>Le premier objectif est atteint dans la mesure où on n’utilise que la loi fondamentale du rayonnement des courants réels (électriques) en excluant tout recours à des courants virtuels (magnétiques).<p>Concernant l’objectif de précision, des comparaisons nombreuses avec des résultats d’un simulateur purement numérique et des mesures indiquent une amélioration pour tous les paramètres mais en particulier pour l’impédance qui est le point faible de tous les modèles existants.<p><p><p>Microstrip antennas and the rectangular microstrip antenna in particular have been studied and used for several decades.<p>As every antenna, the microstrip antenna requires a good analytical model that provides physical insight and an easy prediction of the antenna parameters (resonance frequency, impedance, gain, efficiency and bandwidth).<p>Over the years, two families of models have been developed, each involving many variants: the “transmission line” and the “cavity” models. These models either lack accuracy or are very complex and produce results that may be far away from reality. <p>The objective of this work is double: defining a model as simple and direct as possible and on the other hand as accurate as possible.<p>The first objective has been reached as all our calculations rest on the fundamental radiation formula by real (electrical) currents excluding any virtual (magnetic) currents.<p>Regarding accuracy, comparisons to numerical simulations and measurements show an improvement, in particular with regard to the prediction of the impedance parameters, which is the weak point of all existing models.<p> / Doctorat en Sciences de l'ingénieur / info:eu-repo/semantics/nonPublished

No / The bandwidth of a microstrip patch antenna is expressed in terms of minimum achievable reflection coefficient using an equivalent circuit and the Bode-Fano theory. The bandwidth-reflection coefficient product is found to be proportional to antenna height and largely independent of feed probe position, for small bandwidths. The product can be computed directly from a numerical evaluation of the first-order Bode-Fano integral. Curves are presented showing how the product becomes limited by the feed probe inductance at very large bandwidths. It is concluded that this effect is unlikely to be a limit on the potential bandwidth of a practical patch antenna. If as a minimal correction the feed inductance is tuned out, the realized bandwidth with low order matching or optimal over-coupling shows the expected relationship to the theoretical limit.

Modern wireless communication systems call for ultra wideband operations to meet the continuous growth in the number of users of these systems. Since antenna is an integral part of any wireless communication system (transmitter or receiver), designing antennas with good gain over large bandwidth needs to be considered first. To meet the popular demand, wireless communication systems should be as cheap as possible which require antennas with small size, light weight, low profile and low cost, and that are easy to fabricate and assemble. A type of antenna that satisfies most of these requirements is the microstrip antenna. Most of the wideband techniques for microstrip antennas utilize complicated geometries such as stacked multiple metal/dielectric layers, complicated feed arrangements etc., which elude the primary attraction of microstrip antennas. On the other hand, single layer suspended configurations are considered the best choice as these are simple to fabricate and assemble. The objective of this research is to investigate simple microstrip antennas with large bandwidth. A single layer suspended microstrip configuration was chosen for the purpose. In the first part of the research, the bandwidth was increased to about 50% with linear phase characteristics by optimizing the feed configurations while retaining the overall simplicity. This study has resulted in proposing a criterion for obtaining maximum bandwidth in the suspended microstrip configuration. An analytical model has been developed for such an antenna configuration. Although several analytical tools are available for the microstrip antenna analysis, equivalent circuit based approach proves to be a simple one and offers convincingly accurate results. Another advantage of the proposed equivalent circuit modeling scheme is that it is suitable for computer aided design (CAD). In order to make this approach even more useful, the antenna designed in the first part was modified to meet desired specifications such as reduction in the air gap to make the antenna compact, symmetrical patterns, making antenna circularly polarized (LHCP or RHCP) without changing the feed configuration. Nearly symmetrical patterns were obtained throughout the band of operation by modifying the profile of patch close to the feed strip. Circular polarization (CP) operation has been obtained from the basic antenna by cutting a diagonal slot on the radiator patch. Here the slot orientation decides the type of CP i.e., LHCP or RHCP. In this work obtained of 7.1% axial ratio (3dB) bandwidth with other characteristics unaffected. The overall height of the antenna is reduced by 55% by cutting a slot and re-optimizing the feed strip dimensions. These studies emphasize flexibility offered by the design approach in realizing practical antennas for various applications.

The novel designs of circular microstrip antennas have been investigated in this dissertation. In the linearly polarized designs, the study of single-feed dual-frequency circular microstrip antenna with an open-ring slot has been firstly presented. As for the broadband circular microstrip antenna designs, antennas with two open-ring slots, embedded reactive loading by probe feed and microstrip-line feed have been presented. The antenna bandwidth of them can be enhanced about 4% to 6%. In the circularly polarized designs, we have proposed a circularly polarized microstrip antenna with a spur line. By choosing a suitable length of the spur line, CP operation can be obtained. And then, such a design can be applied to a compact circular patch antenna with bent slots. These reduced the antenna size to be 40%~50% of that of the simple case. Finally, we use the ideas of CP operation with elliptic patch and dual-frequency operation with stacked patch to propose a dual-band circularly polarized stacked elliptic microstrip antenna design. The frequency ratio of this design is about 1.39.

International Telemetering Conference Proceedings / October 30-November 02, 1995 / Riviera Hotel, Las Vegas, Nevada / Conformal printed antennas of arbitrary shape are used for telemetry applications on high velocity vehicles due to their small size and light weight. The design of these antennas is difficult, however, since there are few accurate analytical models that take the effects of curvature into account. This paper discusses a computer aided design (CAD) tool for arbitrarily shaped printed antennas on cylindrical structures based on a rigorous analytical model. The tool is combined with a graphical user interface and can help antenna designers achieve close to optimal performance. An overview of the mathematical model is given here and the CAD tool is used to highlight the effects of curvature on printed antenna performance. Methods of obtaining circular polarization are reviewed.

Lee Wai Ki. / Thesis submitted in: May 2004. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 62-66). / Abstracts in English and Chinese. / Chapter Chapter 1: --- Introduction --- p.8 / Chapter 1.1 --- Motivation --- p.8 / Chapter 1.2 --- Organization of the thesis --- p.10 / Chapter Chapter 2: --- Background Technology --- p.12 / Chapter 2.1 --- Introduction: FUZZY EM CAD formula for impedance of the edge of the patch antenna --- p.12 / Chapter 2.2 --- Fringe field extension of the patch: --- p.12 / Chapter 2.2.1 --- Applying the root of area capacitance formula --- p.12 / Chapter 2.2.2 --- Defining microstrip parallel plate capacitor with infinite substrate --- p.13 / Chapter 2.2.3 --- The parallel plate capacitor formula --- p.14 / Chapter 2.2.4 --- DC fringe field leading to the patch extension --- p.15 / Chapter 2.3 --- Cavity model of the patch --- p.16 / Chapter 2.3.1 --- Cavity model analysis on its internal field --- p.16 / Chapter 2.3.2 --- Input impedance derived from cavity model --- p.19 / Chapter 2.3.3 --- Quality factor of patch antenna --- p.19 / Chapter 2.4 --- Fringe extension applied to cavity model in RF --- p.23 / Chapter Chapter 3: --- Simple one Port wide band multi-layer patch Antenna --- p.24 / Chapter 3.1 --- Introduction --- p.24 / Chapter 3.2 --- Antenna design --- p.25 / Chapter 3.3 --- Measured results --- p.26 / Chapter 3.4 --- Antenna Analysis --- p.29 / Chapter 3.5 --- Conclusion --- p.30 / Chapter Chapter 4: --- Design synthesis of patch antennas of the T-square Probe --- p.31 / Chapter 4.1 --- Introduction --- p.31 / Chapter 4.2 --- The physics interpretation --- p.32 / Chapter 4.3 --- The Smith chart movement by the T-square feed on the patch --- p.33 / Chapter 4.4 --- Conclusion --- p.35 / Chapter Chapter 5: --- Design synthesis of the wideband tuning-fork-shaped feeding for patch antenna --- p.36 / Chapter 5.1 --- Introduction --- p.36 / Chapter 5.2 --- Antenna design --- p.36 / Chapter 5.3 --- The Smith chart movements of the tuning-fork shaped feeding on the patch --- p.37 / Chapter 5.4 --- Conclusion --- p.41 / Chapter Chapter 6: --- "Fork on H-slot feed of multilayer microstrip antenna for wideband, high isolation and low cross polarization" --- p.42 / Chapter 6.1 --- Introduction --- p.42 / Chapter 6.2 --- Antenna analysis - Isolation improvement considerations --- p.44 / Chapter 6.3 --- Antenna design and measured results --- p.46 / Chapter 6.3.1 --- The simulated return loss and current distribution s in various structure of the two port. --- p.47 / Chapter 6.3.2. --- The hardware and the comparison of results --- p.50 / Chapter 6.3.3. --- The simulated properties of the radiation patterns and cross-polarizations --- p.52 / Chapter 6.3.4. --- The comparison of radiation patterns between simulation and hardware --- p.56 / Chapter 6.4 --- Further improvements --- p.58 / Chapter 6.5 --- Conclusion --- p.59 / Chapter Chapter 7: --- Conclusions --- p.60 / Reference --- p.62 / List of Publication --- p.66

Thesis (M.S.)--Florida State University, 2004. / Advisor: Dr. Frank Gross, Florida State University, College of Engineering, Dept. of Electrical and Computer Engineering. Title and description from dissertation home page (viewed 6/15/04). Includes bibliographical references.