Showing papers on "Metamaterial antenna published in 1995"

Microstrip antennas : the analysis and design of microstrip antennas and arrays

Abstract: Microstrip antennas: the analysis and design of microstrip antennas and arrays , Microstrip antennas: the analysis and design of microstrip antennas and arrays , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

Dual-frequency microstrip reflectarray

Abstract: Microstrip antennas are known to have a narrow bandwidth. However, they exhibit many other advantages that make them suitable for mobile and satellite communications. While narrow in bandwidth, microstrip antennas are well-suited for dual-frequency operation. Developments in microstrip reflectarrays have further demonstrated the viability of printed-circuit technology for space communications. Combining the novel characteristics of microstrip reflectarrays with the concept of dual-frequency operation, we examine the feasibility of a stacked dual-frequency microstrip reflectarray. Our results show that accurate CAD tools are essential in the design of dual-frequency microstrip reflectarray.

Two stage double layer microstrip spatial amplifiers

Abstract: Several two stage spatial amplifiers are presented. The amplifiers were constructed on double layer back to back microstrip circuits with a shared ground plane. The ground plane provides an effective isolation between the receiving antenna array and the transmitting antenna array. Furthermore, it serves as a heat sink in high-power amplifier design. The coupling between the two stages is accomplished through microstrip to slot transitions, therefore there is no electrical contact from one layer to another. This facilitates monolithic fabrication of such amplifiers. The measured gain of a 3/spl times/3 spatial amplifier at 9.95 GHz is 18.0 dB. >

Corporate-fed 2/spl times/2 planar microstrip patch sub-array for the 35 GHz band

Abstract: A classical configuration of a planar array of microstrip rectangular patches, fed by a corporate-feed arrangement, is widely used for many applications. There are several reports devoted to the design of such antennas. However, they are based on semi-empirical approaches, especially at mm-wave frequencies. A good choice of an array-feeding-network layout is a cornerstone problem for the antenna's design. The purpose of this report is to give a description of a 2/spl times/2 element planar microstrip-patch sub-array, which can be used as a basis configuration for design of large, high-gain arrays, for the 35 GHz band.

Electric field distribution measurement of microstrip antennas and arrays using electro-optic sampling

Abstract: This paper proposes an electric field distribution measurement method for microwave integrated circuit arrays that uses electro-optic sampling (EOS). The electric fields of a microstrip patch antenna are measured by EOS and compared with the theoretical results calculated by the spectral domain approach. Good agreement between measurement and theory is found. An array antenna composed of two microstrip patches is also assessed by the EOS method and the expected results are experimentally verified. The EOS proposed in this paper is promising to evaluate the electric field distribution of individual antenna elements in large scaled integrated array antennas. >

Analysis and treatment of edge effects on the radiation pattern of a microstrip patch antenna

Abstract: Microstrip antennas have many applications on structures where size and weight constraints are critical. Because of their low profile and conformal nature, they are especially useful for airborne and spacecraft systems. When designing these antennas, it is often assumed that the microstrip elements are mounted on infinitely large ground planes so that the diffraction from the edges of the ground plane are neglected. In practical applications, however, the diffraction from these edges can have a significant affect on the radiation pattern. It would be desirable to have an analytical model that can be used to understand exactly how great this affect is. Treatment of these edges may be necessary to control their effect on the radiation pattern, which can often be accomplished by placing lossy materials in the vicinity of the edges to minimise the fields which diffract from them. Such a technique has been previously successfully applied to control the scattering from the vertex of a wedge using resistive cards, and will be extended here for the problem of controlling radiation patterns.

A microstrip-based quasi-optical polarization rotator array

Abstract: A low-loss quasi-optical Ka-band polarization rotator array with 18% bandwidth has been designed and tested. Each cell of the array consists of a pair of input probe antennas connected via microstrip lines to orthogonally oriented output probe antennas. The design shows promise for use as an active array, as multistage MMIC amplifiers can be inserted in a straightforward manner into each cell. >

A novel slotline-fed microstrip patch antenna

Abstract: A microstrip patch antenna employing a novel feed arrangement is presented. By using the slotline to microstrip coupling, energy is coupled to the radiating patches via a continuous slotline in the microstrip ground plane. This allows the patches and the feeding slotlines to be fabricated on a single substrate minimising device areas in MMICs. Using Hewlett Packard's high frequency structure simulator (HFSS) the electric and magnetic field distribution on a single patch design have been analysed. The results of measurements performed in an anechoic chamber are presented which show the radiation characteristics of a 10 GHz prototype antenna using the new feed mechanism. >

Rigorous analysis of rectangular microstrip antennas with parasitic patches

Abstract: It has been reported that the antenna bandwidth of a microstrip antenna can be significantly increased by adding parasitic patches. Recently, a new microstrip antenna structure with several parasitic patches called the microstrip Yagi array antenna has found applications in mobile satellite systems. One reason for such applications is that the antenna's mainbeam radiation can be tilted away from the broadside direction, due to strong coupling between the driven and parasitic patches. Because of this strong coupling, the performance of a microstrip Yagi array is very sensitive to various array parameters. A rigorous analysis is thus required to accurately determine the performance of a microstrip Yagi array. This problem is studied by using a full-wave analysis and a moment-method calculation. The characteristics of a microstrip Yagi array are studied.

Radiation characteristics of transmission line in PCBs

Abstract: The paper discusses radiated emission at the far zones from PCB circuits, which can be treated as equivalent transmission lines. The differential-mode and common-mode current distributions are analysed by means of a transmission line approach. Then, with the assistance of line antenna theory, the radiated emission produced by these currents are calculated. Finally, computational results are given and compared with experimental results.

Hole-coupled patch antennas

Abstract: An accurate and numerically efficient model for the electromagnetic coupling between a microstrip line and a microstrip patch via an hole is presented. In the framework of the cavity model both the antenna excitation and the reflection coefficient on the line are computed taking into account all the modes in the cavity. Both theoretical and measured results are presented, to assess the accuracy of the model.

Some experimental investigations on aperture‐coupled microstrip antennas at TM11 mode

Abstract: Experimental investigation on the effect of shifting the position of the slot from the center of the aperture-coupled microstrip patch antenna on input impedance, bahdwidth, and resonance frequency at TM11 mode, has been presented. This method is found to be useful for impedance matching in mobile communications, where antennas excited at higher-order modes are preferred. © 1995 John Wiley & Sons, Inc.

CAD for the synthesis of rectangular microstrip antennas

Abstract: There are many powerful CAD-packages for the analysis of microstrip antennas. But the literature hasn't reported any CAD-package for the synthesis of this type of antenna. A PC software for the synthesis of coaxially fed rectangular microstrip antennas is presented, using the improved transmission line method to predict the input characteristics of a rectangular microstrip antenna. Results are shown in which there is good agreement between the synthesis and experimental results obtained by other authors.

Analysis of cylindrical printed slot and slot-coupled microstrip antennas

Abstract: Analysis of microstripline-fed printed slot and slot-coupled microstrip antennas becomes complicated, when the actual currents on the feed line are modeled. Recently, the complexity of the theoretical analysis for such antenna structures has been reduced by using the reciprocity analysis, which considers only the fundamental-mode propagation on the microstrip feedline. The obtained results based on the reciprocity analysis are also found to be in good agreement with the measured data. In this paper, the extension of this method to the analysis of such antenna structures on a cylindrical body is described. Both the input impedance and radiation pattern for the cylindrical printed slot and slot-coupled microstrip antennas with various curvature radii are calculated and discussed.

Reciprocity analysis of an infinite array of offset dual-patch antennas

Abstract: The infinite arrays of probe-fed stacked microstrip patches were investigated in Aberle et al. (1994). It was found that the scan-bandwidth was increased if the dielectric constant of the upper layer was smaller than that of the lower layer according to a certain relationship. Frequency independent matching networks were inserted between the array elements and the feed lines. It is not easy to implement the desired dielectric constant of the upper layer and wideband frequency independent networks are difficult to design. To circumvent the above disadvantages, an infinite array of offset dual-patch microstrip antennas is studied.

Circular polarization microstrip array on a conical surface

Abstract: Antenna elements based on microstrip technology are low profile, conformal, low weight and low cost, as such they are commonly used in many applications. Lately, extensive effort was devoted to compute the radiation characteristics of microstrip elements on flat and cylindrical surfaces, but only minor attention has been given to the analysis of microstrip elements on a conical surface. Such a geometry has a significant importance in satellite and space communication. In this study we utilized the cavity model (1979) to compute the input impedance of the patch. We used spherical wave functions expansion to compute the internal cavity fields and the external radiated fields. The circular polarization of the microstrip element was obtained by exciting two orthogonal modes with 90 deg. phase delay among them. To obtain an omnidirectional azimuth, coverage, three microstrip elements were interconnected and equally spaced along the cone surface. The antenna was built and tested and good agreement between the computed and measured results was obtained.

Scattering from a spherical-circular microstrip antenna

Abstract: Electromagnetic scattering by planar microstrip antennas has received much attention. However, the related scattering studies for conformal microstrip antennas are very scant. In this article, the scattering from a spherical-circular microstrip antenna is investigated. This study is performed by using a rigorous Green's-function formulation in the spectral domain, and the numerical results of the backscattering radar cross section (RCS) of the microstrip antenna are calculated by using Galerkin's moment method. The obtained RCS results of the spherical-circular microstrip antenna are also compared with the results of a corresponding planar circular microstrip antenna to analyze the curvature effect on the scattering from a microstrip antenna.