Showing papers on "Metamaterial antenna published in 1993"
28 Jun 1993
TL;DR: In this article, a dual-band microstrip antenna is proposed, which is within a single structure and does not require vertical connections, and the input impedances are matched at both resonant frequencies in a much easier manner.
Abstract: The authors introduce a novel dual-frequency microstrip antenna which is within a single structure and does not require vertical connections. The resonant frequencies can be varied over a wide range of frequency. The input impedances are matched at both resonant frequencies in a much easier manner than the available dual-band microstrip antennas. The fabrication process is relatively simple. >
21 citations
01 Jan 1993
TL;DR: In this article, a method for the analysis of phased arrays of rectangular slacked microstrip antennas is used in combination with the exact spectral domain Green's function in order to calculate the unknown currents on each array element.
Abstract: This report deals with a method for the analysis of phased arrays of rectangular slacked microstrip antennas. The method of moments is used in combination with the exact spectral domain Green's function in order to calculate the unknown currents on each array element. First arrays based on electrically thin dielectric substrates are investigated. Lateron this model is extended to the case of arrays on electrically thick substrates. In this case a proper model for the feeding coaxial cables has to be used including an attachment mode that ensures continuity of current at the probe/patch transitions. When analysing arrays it is extremely important that the asymptotic-form extraction technique is used. Without this analytical method it is almost impossible to analyse large arrays accurately with an acceptable computation time. More computation time can be saved if interactions in the method of moments matrices between basis functions that are located far away from each other are neglected. In this way these matrices become sparse matrices. Mutual coupling measurements were made on a 7 x 7 array with a single patch layer. The measurements agreed fairly well with our calculations. Two broadband configurations have been investigated, namely a stacked microstrip array on a thick substrate and an array with electromagnetically coupled (EMC) microstrip elements. The mutual coupling level is relatively high in both configurations. Despite of this, it seems that an EMC-microstrip antenna is a very good candidate for the design of broadband microstrip arrays. Smolders, AB. FINITE STACKED MICROSTRIP ARRAYS WITH THICK SUBSTRATES Eindhoven: Fac·ulty of Electrical Engineering, Eindhoven University of Technology, The Netherlands, 1993. EUT Report 93-E-273, ISBN 90-6144-273-7 Address of the author Electromagnetics Division Faculty of Electrical Engineering, Eindhoven University of Technology P.O. Box 513 5600 MB Eindhoven The Netherlands
13 citations
02 Jun 1993
TL;DR: In this paper, a general technique for calculating the radiated electromagnetic fields from an electrically small bulk acoustic wave (BAW) resonator in the vicinity of acoustic resonance is presented.
Abstract: A general technique for calculating the radiated electromagnetic fields from an electrically small bulk acoustic wave (BAW) resonator in the vicinity of acoustic resonance is presented. The BAW resonator is analyzed as an electrically small microstrip antenna on a piezoelectric substrate. By the application of the surface equivalence principle, the device is replaced by equivalent sources. The radiated far fields found from the equivalent sources are integrated over the upper half plane to determine the total amount of radiated electromagnetic (EM) power as a function of frequency. The result is general enough to characterize the EM radiation from arbitrarily shaped metallizations, and the antenna pattern and polarization of the radiation may also be determined. The theoretical results are experimentally confirmed by measuring the radiated EM power spectrum from lithium niobate and quartz resonators. >
10 citations
01 Jan 1993
TL;DR: In this article, the authors presented an experimental and computer simulated appraisal of the operational characteristics of an active antenna module in free running mode and also under the influence of a frequency entrainment signal applied at the first subharmonic and at first harmonic of the free running frequency.
Abstract: Presents an experimental and computer simulated appraisal of the operational characteristics of an active antenna module. The module is operated in free running mode and also under the influence of a frequency entrainment signal applied at the first subharmonic and at the first harmonic of the free running frequency. The degree to which the behaviour of the module can be influenced in each case is examined and potential application areas for each resultant effect described. Further it is shown that it is possible to quantitatively simulate the behaviour of the module for each case examined using a nonlinear circuit based model.
6 citations
28 Jun 1993
TL;DR: In this paper, a novel technique for feeding microstrip antennas is proposed, which is designed to propagate standing waves, instead of traveling waves as is usually done, resulting in a stable and periodic field distribution along this network.
Abstract: A novel technique for feeding microstrip antennas is proposed. The feeding network, made of microstrip lines, is designed to propagate standing waves, instead of traveling waves as is usually done. At its resonance, the incident and reflected signals combine with each other, resulting in a stable and periodic field distribution along this network. Thus, coupled patches can be excited with equal magnitude, and either equal phase or phase opposition, depending on the desired radiation pattern. They also bring an additional resonance, which, added to that of the patch, enhances the input impedance bandwidth. No power dividers or matching stubs are necessary, leading to structural simplicity. Three examples of resonant feeding networks are presented, which provide three different resonating modes. >
6 citations
6 citations
TL;DR: In this article, a novel application of a microstrip array is presented, which uses such flexibility to achieve cosecant-squared beam shaping, and the antenna developed is the shovel-microstrip array antenna.
Abstract: A novel application of a microstrip array is presented. Although microstrip arrays are often made on mechanically flexible substrates for conformal applications, this approach uses such flexibility to achieve cosecant-squared beam shaping. The antenna developed is the shovel-microstrip array antenna. >
4 citations
01 Oct 1993
TL;DR: In this article, a 12-element rectangular microstrip antanna array is used for microwave heating at the frequency of 2.4 GHz with dimensions of 40 × 30 × 2.1 cm3 and a CW power of 1 kW.
Abstract: This paper describes the preliminary considerations, design and first experimental results of a 12-element rectangular microstrip antanna array (applicator) used for microwave heating at the frequency of 2.4 GHz with dimensions of 40 × 30 × 2.1 cm3 and a CW-power of 1 kW The innovative applicator consists of a planararray of electrically thick rectangular microstrip antennas and a stripline reactive power splitter with thick copper conductors at the inner strips and filled with a heat conducting insulation in the input section. Although the applicator is used in the radiating near-field, it is also possible to design a transmit antenna, e.g. for FM - CW radar applications.
3 citations
28 Jun 1993
TL;DR: In this article, the authors presented the analysis and design of a circular microstrip antenna coupled through an annular slot to a coaxial line, which yields a symmetric radiation pattern and a linear polarization that is different from that of the conventionally fed microstrip antennas.
Abstract: The author presents the analysis and design of a circular microstrip antenna coupled through an annular slot to a coaxial line. The annular slot is concentric with the circular patch. This method of coupling yields a symmetric radiation pattern and a linear polarization that is different from that of the conventionally fed microstrip antennas. The structure is analyzed using the finite-difference time-domain (FDTD) technique in cylindrical coordinates. Numerical results are presented. >
3 citations
01 Mar 1993
TL;DR: In this article, three antenna architectures at K and Ka-band frequencies are examined, including directly coupled, gap coupled, and electromagnetically coupled to a microstrip transmission line.
Abstract: The recent discovery of high temperature superconductors (HTS) has generated a substantial amount of interest in microstrip antenna applications. However, the high permittivity of substrates compatible with HTS results in narrow bandwidths and high patch edge impedances of such antennas. To investigate the performance of superconducting microstrip antennas, three antenna architectures at K and Ka-band frequencies are examined. Superconducting microstrip antennas that are directly coupled, gap coupled, and electromagnetically coupled to a microstrip transmission line were designed and fabricated on lanthanum aluminate substrates using YBa2Cu3O7 superconducting thin films. For each architecture, a single patch antenna and a four element array were fabricated. Measurements from these antennas, including input impedance, bandwidth, patterns, efficiency, and gain are presented. The measured results show usable antennas can be constructed using any of the architectures. All architectures show excellent gain characteristics, with less than 2 dB of total loss in the four element arrays. Although the direct and gap coupled antennas are the simplest antennas to design and fabricate, they suffer from narrow bandwidths. The electromagnetically coupled antenna, on the other hand, allows the flexibility of using a low permittivity substrate for the patch radiator, while using HTS for the feed network, thus increasing the bandwidth while effectively utilizing the low loss properties of HTS. Each antenna investigated in this research is the first of its kind reported.
3 citations
01 Oct 1993
TL;DR: A proper treatment of absorbing boundaries is presented for accurate analysis of radiating structures in a time domain 3D-TLM algorithm applied to analyze a microstrip patch antenna.
Abstract: In this paper, a time domain 3D-TLM algorithm has been applied to analyze a microstrip patch antenna A proper treatment of absorbing boundaries is presented for accurate analysis of radiating structures The results obtained for a rectangular patch microstrip antenna compare well with available data
01 Jan 1993
TL;DR: In this paper, the authors present a computer model to study the response of a lossy coupled microstrip interconnect illuminated by an electromagnetic field generated by an in-farfield zone.
Abstract: The authors present a computer model to study the response of a lossy coupled microstrip interconnect illuminated by an electromagnetic field generated by an in the farfield zone. The model allows the computation of currents and voltages induced by the antenna fields of arbitrary angle of incidence and polarization at any point along the coupled microstrip line, which is terminated in passive loads at both ends. The effects of high substrate permittivity and loss tangent on the coupling of the antenna fields into the microstrip is investigated in detail. The author also presents a model for the coupling of the antenna fields to the microstrip when the line is placed in the near field zone of the antenna and the fields are highly nonuniform. The exact formulas for the wave coupling in this specific case contain complicated integrals which can not be evaluated analytically and numerical procedures are used to obtain the final results. >
28 Jun 1993
TL;DR: In this paper, the authors examined several design issues critical to the design of a dual-linear array element, such as feed mechanism and mutual coupling effect, and showed how the design process can be simplified by the aid of a new Printed Antenna Design (PAD) tool developed for designing microstrip antennas.
Abstract: The authors examine several design issues critical to the design of a dual-linear array element, such as feed mechanism and mutual coupling effect. They show how the design process can be simplified by the aid of a new Printed Antenna Design (PAD) tool developed for designing microstrip antennas. Using this tool, it was shown that the dimensions of the patch and the feedlines must be chosen carefully to yield the desired resonant frequency and to simplify the matching process for the feed network. >
18 Aug 1993
TL;DR: In this paper, a novel method of increasing the operational bandwidth of circular microstrip antennas is presented, which increases the operational frequency of the microstrip antenna by 1.O% to 1.5% of the resonant frequency.
Abstract: Aerodynamics and spatial considerations make it desirable to use microstrip antennas which have a very low profile in many applications. Most of the microstrip antennas in use have a resonant structure, and as a result operate over a narrow band of frequency, typically 1.O% to 1.5% of the resonant frequency. A novel method of increasing the operational bandwidth of circular microstrip antennas is presented. >
28 Jun 1993
TL;DR: In this article, a numerical analysis of the gain characteristics and radiation patterns of a circular patch microstrip antenna with a dielectric element is presented, which is confirmed that Hankel domain analysis is an effective method.
Abstract: A numerical analysis of the gain characteristics and radiation patterns of a circular patch microstrip antenna with a dielectric element is presented. Numerical results are found to be in a good agreement with experimental data. It is confirmed that Hankel domain analysis is an effective method. >
19 Oct 1993
TL;DR: In this paper, a microstrip array antenna directly coupled to nonradiating edges is analyzed and the equivalent circuit of the array antenna is obtained by the equivalent transmission line model and the radiation admittance parameters derived from the analysis method for the slotted parallel-plate waveguide filled with homogeneous dielectric.
Abstract: In order to improve directivity, a microstrip array antenna directly coupled to nonradiating edges is analysed. The equivalent circuit of the array antenna is obtained by the equivalent transmission line model and the radiation admittance parameters derived from the analysis method for the slotted parallel-plate waveguide filled with homogeneous dielectric. The calculated values of the return loss and the radiation pattern are presented and compared with the measured values. The calculated values are observed to be in fairly good agreement with the measured values. >