Novel broadband designs of planar antenna with an air substrate are proposed in this dissertation, The operating bands considered include the GSM/DCS band and ISM band. Several antenna designs capable of dual- polarized operation, circularly polarized radiation, and diversity operation are also presented.In these antenna designs, prototypes were constructed. The measured input impedance, return loss, radiation pattern, and antenna gain are presented and discussed. The commercially available simulation software are also used in verifying the measured results.As for the broadband planar antenna designs, the impedance bandwidth obtained reaches about 10% (1.5¡G1VSWR). For the circularly polarized designs, we propose a low-cost, broadband circularly polarized patch antenna fed by a coplanar probe feed, and circular polarization (CP) radiation over a wide frequency range (¡Ö10%) can be achieved. High isolation between two feeding ports (S21 less than ¡V30 dB) can be obtained for the constructed prototype of the proposed dual-polarized design. On the other hand, wrapping a planar monopole into a compact box-like structure allows the antenna¡¦s total height less then 5% of the wavelength at 900 MHz. The proposed antennas are suitable for wireless communications applications.

Yes / The antenna presented in this study is a compact wideband monopole with wideband circular polarization that can be used across the whole antenna bandwidth. A rectangular C-shaped patch is partially covered by a ground plane in the proposed planar monopole antenna. Inserting a rectangular stub to the ground plane, etching a slit at the antenna patch, and adding a semicircular stub at the top of the antenna feed line increase the antenna impedance bandwidth (BW) and axial ratio bandwidth (ARBW). An FR4 substrate with overall dimensions of 25 mm×25 mm×1.6 mm is used to create the antenna. The antenna's observed impedance BW is 70% (4.55 GHz in the 4.3-8.85 GHz band), while the measured broadside ARBW is improved to a value of 82.2 percent (5.3 GHz along the range 3.8-9.1 GHz). The impedance BW is perfectly covered by the ARBW; hence the antenna can be considered circularly polarized throughout its operational spectrum. Within the antenna BW, the measured gain is greater than 1.5 dB.

In this thesis, two novel antennas and three advanced design concepts for further studies are presented. Firstly, the design of diversity dual-band inverted-F monopole antenna using two back-to-back stacked metallic strips for operating in the 2.4 and 5.2 GHz WLAN band is presented. Secondly, the diversity dual-band inverted-F monopole antenna mounted vertically at the edge of a system circuit board is studied. Finally, three advanced design concepts are discussed to demonstrate the methods of controlling radiation patterns to achieve better radiation characteristics of the antenna.

This work deals with the principles on which they are based multiband antennas, especially for GSM (900/1800). It then focuses on different ways you can implement these multi-band antennas, mainly deals with structures that can be easily realized using planar technology. These antennas was designed and optimized in electromagnetic simulation software. Selected antenna was practically realized.

Approved for public release; distribution is unlimited / The Linearly Tapered Slot Antenna (LTSA) had been investigated and developed experimentally; its applications have primarily been based on empirical designs. An accurate theoretical model based on Moment Methods (MM) is developed here to study the radiation characteristics of the LTSA. Using the MM solutions to the reaction integral equation, this thesis presents an analysis to model and explain the LTSA behavior. The effects of variable design parameters on radiation patterns are studied. Discussion is augmented by relating predicted radiation patterns to calculated current distributions on the antenna surface. Conclusions are made regarding optimum designs for the LTSA. Relevant observations are made concerning the extensive computational tasks and the computer resources required for the MM model. / http://archive.org/details/modelingbehavior00kell / Major, United States Army

Novel printed monopole antennas, including diversity antennas, monopole array antennas and broadband antennas for WLAN operation, are experimentally studied and presented in this dissertation. These proposed antennas can be printed on dielectric substrates and practically integrated with system circuit boards by using printed circuit board technique. Also, the proposed antennas are low cost in fabrication and the reliability of system circuit boards can be improved. First, the design of the diversity antenna, which mainly comprises two substantially orthogonal printed monopoles and are placed symmetrically with respect to a protruded ground plane of T shape, shows good isolation between the two feeding ports of the proposed antenna. Second, the design of the printed array antenna, which comprises three equally-spaced equilateral-triangular monopoles, is proposed. Among the three monopoles, the center one has a larger size, which mainly controls the lower operation band, and the other two monopoles have a smaller size for higher operation band and show higher antenna gain and wider operating bandwidth. Finally, the quasi-self-complementary antenna is introduced. With compact size and wide bandwidth achieved, the proposed antenna is suitable for a mobile communication device, and can also provide good spatial diversity to combat the multi-path interference problem when mounting two proposed antennas appropriately spaced on a WLAN card.

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 paper, at the beginning, we focused our studies on the practical planar antenna designs for wireless communication. We also proposed several antenna designs operating at the widely used bands, such as the ISM, GSM, GPS, 3G bands and their combinations. For the antenna designs at these bands, the circularly polarized wide slot antenna and planar monopole antenna with the conducting plate loading for ISM band application, shorted stacked mircostrip antenna for 3G band application, and the low cost high gain 8Í8 stacked patch array for dual ISM band application have been presented. To provide mobile communication and the accurate position of the user as well, the GSM/GPS dual-band antenna suitable for vehicle application is presented. Finally, the GSM/ISM dual-band antenna designed for the personal communication and wireless local area network is also shown. The performance we have achieved in these antenna designs not only satisfy the specific requirements of the system, but also show good antenna pattern, and gain.

Novel designs of planar antennas including the feed network for improving the antenna performance improvement (CP axial-ratio bandwidth, XPL, port decoupling for dual-polarized operation, and harmonic control) or achieving dual-band operation are presented. This thesis, comprises five sections. Firstly, for obtaining broadband CP designs, the Wilkinson power divider and branch-line coupler are used. The 3-dB axial ratio CP bandwidths of all proposed antennas are larger than 30%. Secondly, the dual broadband patch antennas including a stopband network are proposed. Thirdly, the dual-polarized patch antenna with high XPL and isolation between two ports by using a Wilkinson power divider with a 180¢X phase shift between its two ports is proposed. Fourthly, the dual-band and dual-polarized patch antenna suitable for base-station antenna applications for mobile communications systems is studied. Finally, the harmonic control study of a square microstrip antenna is presented.

This study is focused on designing conformal antennas to be deployed with the inflatable wings for unmanned aerial vehicles (UAV). The main emphasis is on utilizing the structure of the wing to develop antennas for various frequency bands, while maintaining the wing’s aerodynamic performance. An antenna modeler and optimizer software called 4NEC2 and a program called WIRECODE were used to design and determine the characteristics of the antennas. The effect of flexibility of the inflatable wing on the antenna characteristics during flight is also evaluated.