Showing papers by "Constantine A. Balanis published in 2011"
TL;DR: In this article, a modified bow-tie antenna with reduced metallization was designed and fabricated at the Flexible Display Center (FDC) of Arizona State University (ASU).
Abstract: Design, simulation, fabrication and measurement of two different novel flexible bow-tie antennas, a conventional and a modified bow-tie antenna with reduced metallization, are reported in this paper. The antennas are mounted on a flexible substrate fabricated at the Flexible Display Center (FDC) of Arizona State University (ASU). The substrate is heat stabilized polyethylene naphthalate (PEN) which allows the antennas to be flexible. The antennas are fed by a microstrip-to-coplanar feed network balun. The reduction of the metallization is based on the observation that the majority of the current density is confined towards the edges of the regular bow-tie antenna. Hence, the centers of the triangular parts of the conventional bow-tie antenna are removed without compromising significantly its performance. The return losses and radiation patterns of the antennas are simulated with HFSS and the results are compared with measurements, for bow-tie elements mounted on flat and curved surfaces. The comparisons show that there is an excellent agreement between the simulations and measurements for both cases. Furthermore, the radiation performance of the modified bow-tie antenna is verified, by simulations and measurements, to be very close to the conventional bow-tie.
109 citations
TL;DR: In this paper, a three-element compact Yagi-Uda antenna is proposed that maintains a high absolute gain and low VSWR over a 10% fractional bandwidth with an element spacing of 0.053λ.
Abstract: A three-element compact Yagi-Uda antenna is pro posed that maintains a high absolute gain and low VSWR over a 10% fractional bandwidth with an element spacing of 0.053λ. The proposed Yagi-Uda antenna uses a director and reflector to create a dual resonance and approach superdirectivity at each resonant frequency. By adjusting the reflector and director's resonant frequency, the gain and bandwidth of the antenna can be maximized. The driven element has one folded arm to increase the impedance of the antenna. The reflector and director elements are bowtie de signs to increase the bandwidth. The measured impedance and gain agrees well with the computational model.
23 citations
07 Mar 2011
TL;DR: In this article, a modified bow-tie antenna with reduced metallization is presented, where the antenna is mounted on a flexible substrate which is fabricated at the Flexible Display Center (FDC) of Arizona State University (ASU).
Abstract: This paper presents design, simulation, fabrication and measurement of a modified bow-tie antenna with reduced metallization. The antenna is mounted on a flexible substrate which is fabricated at the Flexible Display Center (FDC) of Arizona State University (ASU). The substrate is heat stabilized polyethylene naphthalate (PEN) which allows the antenna to be flexible. The antenna is fed by the aid of a microstrip-to-coplanar feed network balun. The reduction of the metallization is based on the observation that the majority of the current density is confined towards the edges of the regular bow-tie antenna. Hence, the centers of the triangular parts of the bow-tie antenna are removed. The radiation performance of the modified bow-tie is verified to be very close to the conventional bow-tie by simulations and measurements.
14 citations
TL;DR: A seven-element helicopter-mounted microstrip-patch switched-beam antenna array for satellite communications (SATCOM) is described and the effects of the blades of the helicopter on the patterns of the antenna were investigated.
Abstract: A seven-element helicopter-mounted microstrip-patch switched-beam antenna array for satellite communications (SATCOM) is described. The performance of the array antenna was simulated. A prototype was constructed, and measurements of the antenna's patterns were made. The effects of the blades of the helicopter on the patterns of the antenna were investigated. Fluctuations of 10 dB or more in magnitude due to the effects of the blades were observed in the patterns.
12 citations
03 Jul 2011
TL;DR: In this article, the reflection phase response of a flexible high impedance surface (FHIS) is measured in the anechoic chamber and compared with that of a flat FHIS.
Abstract: This paper presents the fabrication and reflection phase measurements of a flexible high impedance surface (FHIS). The surface is fabricated by using DuPont pyralux polyimide as the substrate. Cyanoacrylate is used to adhere the samples of polyimide. The reflection phase response of the FHIS, which is curved in the form of a cylinder, is measured in the anechoic chamber and compared with that of the flat FHIS. As expected, reflection phase characteristics of the curved FHIS are polarization dependent and slightly different than those of the flat one. The measured reflection phase characteristics of the curved FHIS will be compared with simulations which presently are under consideration.
6 citations
Patent•
29 Nov 2011TL;DR: Embodiments of flexible identification systems are described in this article, and related methods are also disclosed in the same publication, as well as in the references therein, and in the present publication.
Abstract: Embodiments of flexible identification systems are described herein. Other embodiments and related methods are also disclosed herein.
6 citations
03 Jul 2011
TL;DR: Results show an improvement in the bit-error-rate (BER) performance when non-uniformly spaced taps are used and some alternatives to improve the performance of the GPS system are reported.
Abstract: The Global Positioning System (GPS) is widely used for many applications but its performance can be impacted significantly by the environment. This can be overcome to a large extend by processing the signal in space and time. The space processing is achieved with a seven element planar array followed by an algorithm to calculate the antenna weights in such a way that the interferences can be nulled. The time processing is implemented with uniformly-spaced tap delays. This paper reports some alternatives to improve the performance of the system. First, a spherical array replaces the present planar array to increase the line-of-sight (LOS) at low elevation angles. Then, the tap delay spacing is incorporated. Results show an improvement in the bit-error-rate (BER) performance when non-uniformly spaced taps are used.
4 citations
07 Mar 2011
TL;DR: This paper compares simulations and measurements of the input impedance of a ferrite-loaded CBS antenna based on the non-uniform field distribution with thosebased on the uniform field distribution.
Abstract: When computing the permeability tensor of the ferrite material, it is often assumed that the internal magnetic field is uniform. In this paper we compare simulations and measurements of the input impedance of a ferrite-loaded CBS antenna based on the non-uniform field distribution with those based on the uniform field distribution.
1 citations
03 Jul 2011
TL;DR: In this article, a flexible bow-tie was fabricated at the Flexible Display Center (FDC) of Arizona State University (ASU), where the antenna was flexed in the form of a cylinder and its radiation properties were obtained for different radii of curvature.
Abstract: This paper presents simulation and measurement of a flexible bow-tie which is fabricated at the Flexible Display Center (FDC) of Arizona State University (ASU). The substrate is heat stabilized polyethylene naphthalate (PEN) which allows the antenna to be flexible. The antenna is flexed in the form of a cylinder and its radiation properties are obtained for different radii of curvature. The return loss, radiation patterns and realized gain of the flexed antenna were compared with those of the flat antenna.
1 citations
20 Oct 2011
TL;DR: In this paper, the development of the Kouyoumjian & Pathak diffraction coefficient is summarized and applications of the UTD on basic and complex structures (from ground planes to airframes), based on my own personal experience, are presented and the impact of the K & P UTD diffractions coefficient is highlighted.
Abstract: The development of the Kouyoumjian & Pathak UTD diffraction coefficient will be summarized Applications of the UTD on basic and complex structures (from ground planes to airframes), based on my own personal experience, will be presented and the impact of the K & P UTD diffractions coefficient will be highlighted
1 citations
07 Mar 2011
TL;DR: In this paper, it was shown that the known stochastic fading models, Rayleigh and Rician, can be obtained by treating multipath deterministically, that is, by solving the electromagnetic scattering problem.
Abstract: Multipath modeling is presented using infinitely long cylinders. It is shown that the known stochastic fading models, Rayleigh and Rician, can be obtained by treating multipath deterministically, that is, by solving the electromagnetic scattering problem.