Doctor of Science in Engineering - Engineering / This paper describes the formulation of a design procedure for the rectangular, probe-fed and rectangular, electromagnetically coupled patch antennas. The design procedure is presented in the form of design curves. The design curve data was generated by solving a bandwidth optimization problem subject to a specified minimum gain constraint. Given a particular performance requirement, an appropriate antenna geometry can be found using the design curves. An unavoidable tradeoff between the gain and impedance bandwidth performance parameters is evident from the design curves. The bandwidth and minimum gain configurations for design of the probe-fed patch range from 6.2% and 9.9dBi to 13.2% and 6.1dBi respectively. The bandwidth and minimum gain configurations for design of the electromagentically coupled patch range from 9.5% and 9.7dBi to 44% and 6.0dBi respectively.

Abstract In this paper, an algorithm for accurately finding the position, orientation and dipole moment of a transmitting dipole antenna buried in rock is presented. The algorithm is based on simplified radiation equations that are shown to be valid within a region of space in the extreme near field surrounding the antenna called termed quasi-static region. Within this region, medium dependent propagation effects are negligible, allowing accurate, medium independent resolution of position, orientation and dipole moment. The magnetic field magnitude and direction values observed at a number of arbitrarily located points in space are used by the algorithm to generate a system of nonlinear equations. This system of equations is solved using a simultaneous multi-variable Newton-Raphson solver with line searches and backtracking providing a measure of global convergence. An additional method, based on an iterated random search, further improves the global convergence capability of the algorithm. If the dipole moment of the transmitting antenna is known, measurements from two observer points are sufficient to resolve the position and orientation of the dipole. If the dipole moment is unknown, three observer points are required to solve for the unknown position, orientation and dipole moment. The algorithm is able to find an exact solution using exact theoretical measurements, and a minimised least squares solution where measurements are subject to noise. The theory relating to the algorithm is discussed including distance-frequency relations for the quasistatic region of a number of common rock types. Probabilistic modelling, simulation and test results of the algorithm are also included.

Optimal missile guidance and flight performance require accurate and continuously updated in-flight coordinate data. The Global Positioning System (GPS) is used for this positional awareness. However, due to missile rotation and orientation variations during flight, GPS signal reception using traditional antennas may be intermittent. To remain cost competitive, Stellar Exploration Inc. is developing a low-cost omnidirectional GPS antenna for guided missile prototypes. In this thesis, existing products and design techniques are examined, design constraints for supersonic missile applications are investigated, and corresponding performance goals are established. A conformal microstrip patch antenna is developed and simulated in Agilent’s Advanced Design System (ADS). The resulting antenna is constructed and characterized. Prototype testing verifies that the antenna maintains GPS signal lock regardless of orientation. The final cost is significantly lower than existing conformal products. A second revision investigates enhanced modeling, dimensional reductions (via increased dielectric constant), and radome construction. Performance is compared to first revision antenna results and differences are examined. Suggestions for further revisions are discussed.

<p>The study is concerned with how the hane effects on matching on mobile terminal antennas.</p>

Thesis (Ph.D.)--City University of Hong Kong, 2006. / "Submitted to Department of Electronic Engineering in partial fulfillment of the requirements for the degree of Doctor of Philosophy" Includes bibliographical references (leaves 179-189)

<p>Patch antenna is one of the most rapidly popular topics in the antenna field in the past twenty years. In high-performance aircraft, spacecraft, satellite and missile applications, where size, weight, cost, performance, ease of installation, and aerodynamic profile are constraints, low profile antennas may be required. [7].</p><p>The project is to develop a single patch antenna operating on a specific frequency 1420MHz. The frequencies near to 1420MHz are worth to observe because the hydrogen in throughout of the space can be mapped by the observation of the 21 – cm wavelength line which is corresponding to 1420 MHz radiation. The final product antenna will be used in a radio telescope as a part of the signal receiving system.</p><p> The work within the project contains simulation, fabrication and test of final antenna. The simulation work was carried out in advanced design system which is developed by Agilent technologies, USA. The most different feature of the project is that, comparing to normal patch antenna, usually 50 ohms is selected as the matching impedance, while in this project we made it conjugate to the input impedance of the LNA. In this way we can save extra components, as well as energy consuming.</p>

With the increasing demand for high performance communication networks and the proliferation of mobile devices, significant advances in antenna design are essential. In recent years the rising demands of the mobile wireless communication industry have forced antennas to have increased performance while being limited to an ever decreasing footprint. Such design constraints have forced antenna designers to consider frequency agile antennas so that their behavior can adapt with changing system requirements or environmental conditions. Frequency agile antennas used for mobile handset applications must also be inexpensive, robust, and make use of electronic switching with reasonable DC power consumption. Previous works have addressed a number of these requirements but relatively little work has been performed on frequency agile dielectric resonator antennas (DRAs). The objective of this thesis is to investigate the use of DRAs for frequency reconfigurability. DRAs are an attractive option due to their compactness, very low losses leading to high radiation efficiencies (better than 95%) and fairly wide bandwidths compared to alternatives. DRA’s are also well suited for mobile communications since they can be placed on a ground plane and are by nature low gain antennas whose radiation patterns typically resemble those of short electric or magnetic dipoles. One way to electronically reconfigure a DRA, in the sense of altering the frequency band over which the input reflection coefficient of the antenna is below some threshold, is to partially load one face of the DRA with a conducting surface. By altering the way in which this surface connects to the groundplane on which the DRA is mounted, the DRA can be reconfigured due to changes in its mode structure. This connection was first made using several conducting tabs which resulted in a tuning range of 69% while having poor cross polarization performance. In order to address the poor cross polarization performance a second conducting surface was placed on the opposing DRA wall. This technique significantly reduced the cross polarization levels while obtaining a tuning range of 83%. The dual-wall conductively loaded DRA was then extended to include a full electronic implementation using PIN diodes and varactor diodes in order to achieve discrete and continuous tuning respectively. The two techniques both achieved discrete tuning ranges of 95% while the varactor implementation also had a continuous tuning range of 59% while both maintaining an acceptable cross polarization level.

With the increasing demand for high performance communication networks and the proliferation of mobile devices, significant advances in antenna design are essential. In recent years the rising demands of the mobile wireless communication industry have forced antennas to have increased performance while being limited to an ever decreasing footprint. Such design constraints have forced antenna designers to consider frequency agile antennas so that their behavior can adapt with changing system requirements or environmental conditions. Frequency agile antennas used for mobile handset applications must also be inexpensive, robust, and make use of electronic switching with reasonable DC power consumption. Previous works have addressed a number of these requirements but relatively little work has been performed on frequency agile dielectric resonator antennas (DRAs). The objective of this thesis is to investigate the use of DRAs for frequency reconfigurability. DRAs are an attractive option due to their compactness, very low losses leading to high radiation efficiencies (better than 95%) and fairly wide bandwidths compared to alternatives. DRA’s are also well suited for mobile communications since they can be placed on a ground plane and are by nature low gain antennas whose radiation patterns typically resemble those of short electric or magnetic dipoles. One way to electronically reconfigure a DRA, in the sense of altering the frequency band over which the input reflection coefficient of the antenna is below some threshold, is to partially load one face of the DRA with a conducting surface. By altering the way in which this surface connects to the groundplane on which the DRA is mounted, the DRA can be reconfigured due to changes in its mode structure. This connection was first made using several conducting tabs which resulted in a tuning range of 69% while having poor cross polarization performance. In order to address the poor cross polarization performance a second conducting surface was placed on the opposing DRA wall. This technique significantly reduced the cross polarization levels while obtaining a tuning range of 83%. The dual-wall conductively loaded DRA was then extended to include a full electronic implementation using PIN diodes and varactor diodes in order to achieve discrete and continuous tuning respectively. The two techniques both achieved discrete tuning ranges of 95% while the varactor implementation also had a continuous tuning range of 59% while both maintaining an acceptable cross polarization level.

The study is concerned with how the hane effects on matching on mobile terminal antennas.

This thesis work is concerned with the design and performance analysis of purely textile antenna for wireless applications. The materials used for radiating element, ground plane and dielectric substrate are purely textile. Two types of antennas are studied, the microstrip patch antenna and RFID tag antenna. Each type of antenna is designed and fabricated using two different conductive textile materials as radiating element.  The radiating element and ground plane of conventional printed antenna is manufactured with the metal plating on a solid dielectric substrate. The radiating element which is used in this thesis work has different characteristics as compared to printed antenna because it is made of conductive textile material which is less conductive than metal and elastic in nature. Each conductive textile material has different surface resistivity. The study has been made to analyze the effect on gain and radiation efficiency of the antenna when different conductive textile material is used as the radiating element. The measured results of the fabricated antennas present the full potential of conductive textile materials to be used as an antenna.