Showing papers on "Metamaterial antenna published in 1985"

Electric surface current model for the analysis of microstrip antennas on cylindrical bodies

Abstract: An approach to the analysis of microstrip antennas on cylindrical bodies is presented. The printed radiator is replaced by as assumed surface current distribution, and the fields are solved taking into account the presence of the dielectric layer and the metallic cylinder. Calculation takes place in the Fourier domain. The far field, calculated asymptotically from this solution, is used to get the radiation patterns of the wraparound antenna for any dielectric and the half-wavelength patch for \epsilon_{r} = 1 .

Directly coupled multiple resonator wide-band microstrip antennas

Abstract: Three new configurations for increasing the impedance bandwidth of the microstrip patch antennas are described. In these configurations, additional resonators are directly coupled through short sections of microstrip line to the radiating edges, nonradiating edges, and all the four edges of the rectangular patch antennas, respectively. Green's function approach and segmentation method are used for the analysis. The experimental results are in reasonable agreement with the analysis and impedance bandwidths of 548 MHz, 605 MHz, and 810 MHz are obtained for these three configurations, respectively in S -band (substrate thickness = 0.318 cm and \epsilon_{r} = 2.55 ). The variation in the radiation pattern over this impedance bandwidth is discussed.

Analysis of a microstrip array and feed network

Abstract: An analysis technique for a microstrip array is presented. The array elements and mutual coupling between elements are analyzed by a method of moments (MM) solution of the exact integral equation. The combination of the microstrip array elements, plus the microstrip transmission line feed network is analyzed using a generalized Thevenin theorem. The method is applied to the specific problem of the series fed microstrip array.

Monolithic design of dual-band microstrip antennas using reactive loading

Abstract: Design To most simply model the previously investigated coaxially loaded antennas one can straightforwardly substitute a short-circuited microstrip line attached to the edge of a rectangular patch element. Use of a coaxial load was considerably more flexible, however, since the separation between resonances as well as the resonant frequencies themselves could also be adjusted by moving the load position away from the edge. To emulate this variation the microstrip line has also been designed with a specified "inset" dimension as shown in figure 1. Unfortunately positioning the load in the interior of the patch results in yet another parameter, g, the gap spacing between the line and the radiator. This parameter seems to have little effect on the upper resonance but tends to reduce the lower resonant frequency as the gap spacing is

Characteristics of microstrip antennas with a superstrate

Abstract: A method of analyzing and/or improving printed circuit antenna performance by the addition of a superstrate (cover) layer has recently been discussed for the case of a Hertzian dipole [1]. In this paper, the characteristics of rectangularly shaped microstrip antennas involving a superstrate are investigated using the method of moments. Results for center fed microstrip dipoles as well as microstrip antennas excited by electromagnetic coupling from a microstrip transmission line are presented. Mutual coupling is also discussed and the effect of the superstrate layer on microstrip antenna parameters is analyzed.

The open-ring microstrip antenna

Abstract: The open ring microstrip structure has been studied in recent years for various applications in microwave circuits and as antenna element [1-3]. Even though a considerable amount of analytical and experimental work has been done on the resonant frequency, the corresponding field distribution for various modes, the Green's function and the input impedance of such an open ring structure, the work on the radiation characteristics such as the radiation pattern and the directivity have been somewhat limited [1-5]. In this paper the expressions for the radiation fields of an open ring structure are derived by utilizing the simple theory based on the cavity model and the resultes for the radiation pattern for typical lower order modes are presented.

Frequency Agile Circular Microstrip Antennas

Abstract: A method to control the operating frequency of circular microstrip antennas has been investigated theoretically and experimentally. The method consists in the placement of shorting posts at appropriate locations within the input region of the antenna. The analytic and measured results have been compared to prove the validity of the models developed.

Geometrical theory of a one‐dimensional microstrip resonator: The effect of topside charges and currents

Abstract: The effects of fields which penetrate from underneath a microstrip patch antenna to the top of the patch can affect the resonance condition for this antenna. Previous cavity models for the rectangular patch have ignored this effect. In this paper, we present an analysis of a one-dimensional microstrip resonator where topside effects are accounted for. The influences on the unloaded radiation Q and on the resonant frequency are examined as functions of the substrate permittivity.

Accurate estimation of microstrip transmission line impedance

Abstract: This paper describes work done on the modelling of microstrip transmission line structures on dielectric substrates, and measurements performed on test structures fabricated on almina. The work employs new techniques in both of these areas. The importance of accurate analysis and measurement of these types of circuits is paramount, as they are important building blocks in microwave integrated circuit design with applications to a variety of microstrip antenna and device structures. This is especially

Radiation characterstics of annular microstrip antenna

Abstract: A considerable amount of work has been done in recent years on the resonant behavior and the radiation characteristics of annular microstrip structures. The radiation fields have been evaluated by utilizing a host of techniques ranging from the use of a simple cavity model to the use of the spectral domain technique in Fourier-Hankel transform domain and the use of the method of matched asymptotic expansion. In this paper, known closed form expressions for radiation fields based on the cavity model are used to derive the expressions for radiation resistance, directivity, bandwidth and other characteristics of annular microstrip antennas. The results conform to similar results for other microstrip antennas. A simple method to calculate radiation characteristics such as radiation resistance, directivity, and bandwidth together with some typical results for annular micros trip antennas has been considered. The results should be helpful in design of such antennas.