Radiation characteristics of spherical triangular array antenna
TL;DR: In this article, a type of spherical triangular array composed of turnstile elements is numerically analyzed and discussed, and it is found that the spherical array proposed here is able to scan its beam up to large angle without variation of the directivity and the circular polarization property.
Abstract: Radiation characteristics of a type of spherical triangular array composed of turnstile elements are numerically analyzed and discussed. It is found that the spherical array proposed here is able to scan its beam up to large angle without variation of the directivity and the circular polarization property.
Citations
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TL;DR: A full solid angle scanning cylindrical-and-conical (CYLCON) conformal phased array antenna (PAA) is designed and a microstrip Yagi antenna with low profile and small size is proposed and discussed.
Abstract: In this paper, a full solid angle scanning cylindrical-and-conical (CYLCON) conformal phased array antenna (PAA) is designed. First, a microstrip Yagi antenna with low profile and small size is proposed and discussed. Second, a cylindrical conformal Yagi antenna array consisting of 24 aforementioned 8-element Yagi antennas is designed and optimized. Simulation results show that the Yagi antenna array can realize low-elevation beam scanning in the region of $ 0 {^{\circ }} \le \theta \le 30 {^{\circ }}$ , $30 {^{\circ }} \le \varphi \le 150 {^{\circ }}$ with low sidelobe levels and sharp beams. Third, CYLCON conformal microstrip antenna arrays are developed to realize the broadside beam scanning. Afterwards, an integrated PAA by combining the aforementioned conformal arrays along with feeding networks is constructed to achieve full solid angle scanning. Finally, a prototype is fabricated, the measured results show that it can realize beam scanning in the regions of $ 0 {^{\circ }} \le \theta \le 30 {^{\circ }}$ , $30 {^{\circ }} \le \varphi \le 150 {^{\circ }}$ , and $30 {^{\circ }} \le \theta \le 180 {^{\circ }}$ , $60 {^{\circ }} \le \varphi \le 120 {^{\circ }}$ , which meet well with those of the simulated. By arranging proper number of arrays along the perimeter accompanied with the switchable feeding configurations, a full solid angle scanning can be achieved.
42 citations
TL;DR: In this paper, the spherical-coordinate finite-difference time-domain method is applied to numerical analysis of phased array of monopoles distributed over a sphere, where the outer boundary of the given problem is modeled by accurate spherical coordinate anisotropic perfectly matched layer.
Abstract: In this paper, the spherical-coordinate finite-difference time-domain method is applied to numerical analysis of phased array of monopoles distributed over a sphere. Outer boundary of the given problem is modeled by accurate spherical- coordinate anisotropic perfectly matched layer. The problem of increased cell aspect ratio near the sphere poles causing degradation of results is solved by dispersion optimization through artificial anisotropy. The accuracy of the approach is verified by comparing a model case with an exact solution. Finally, radiation patterns obtained by frequency-domain near-to-far-field transform and s-parameters of the array elements are presented and validated by comparing with measurement data.
30 citations
Cites background from "Radiation characteristics of spheri..."
...Another version of spherical array, with turnstile antennas as array elements, is numerically analyzed and discussed in [6]....
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Dissertation•
01 Jan 2005
TL;DR: This dissertation considers beamformer design and direction finding for a broadband source using concentric ring array (CRA), that contains many concentric rings of different radii that has several advantages including the flexibility in array pattern synthesis and adaptive array design.
Abstract: Sensor arrays have been used widely in applications including radar, sonar, seismology, biomedicine, communications and imaging. A very popular type of sensor array is circular array, which has almost invariant array pattern in azimuthal plane. This dissertation considers beamformer design and direction finding for a broadband source using concentric ring array(CRA) that contains many concentric rings of different radii. The multi-ring structure of a CRA has several advantages including the flexibility in array pattern synthesis and adaptive array design. We first proposed three CRA array pattern synthesis techniques, which can be used to control the sidelobe and/or mainlobe width of the array pattern of a deterministic broadband beamformer. We then proposed a flexible partially adaptive broadband beamformer design based on element-space approach. Finally, we proposed an efficient direction finding technique for broadband source using CRA. The proposed design techniques are corroborated by experiments from simulated as well as measured data.
8 citations
Journal Article•
TL;DR: In this article, the radiation characteristics of a circularly polarized conical beam spherical slot array antenna for applying to the mobile satellite communication subscriber are presented. But the antenna is not suitable for the tracking system, since the azimuthal pattern is omnidirectional.
Abstract: SUMMARY This paper presents the radiation characteristics of a circularly polarized conical beam spherical slot array antenna for applying to the mobile satellite communication subscriber. The structure of the antenna is easy to fabricate i.e., a ring of perpendicular slot pairs cut on an outer surface of a concentric conducting spherical cavity enclosed by the conducting conical surface with the simple feeding structure, and a linear electric probe excited at the center of the inner surface of the cavity. Radiation fields of a spherical slot array antenna are calculated by superposing the patterns of all the slots. From the numerical results of the radiation pattern, in both elevational and azimuthal planes, it is obvious that the conical beam is realized. The elevational beam direction is low, which is suitable for installing in the land mobile subscriber unit located far from the equator. The tracking system is not necessary because the azimuthal pattern is omnidirectional. Directivity of the antenna for various spherical radii and angles of slot positions are illustrated as the guidelines for the design. Experimental results are in good agreement with the predictions.
6 citations
14 Oct 2003
TL;DR: In this paper, two classes of possible element arrangements are devised by placing the radiating elements at the vertices of some canonical polyhedra and by randomly dispersing them on a spherical surface with uniform spatial density.
Abstract: Optimal three dimensional array configurations for adaptive applications are investigated in this paper. To accomplish uniform beam scanning, two classes of possible element arrangements are devised by placing the radiating elements at the vertices of some canonical polyhedra and by randomly dispersing the radiating elements on a spherical surface with uniform spatial density. In both these pseudo-uniform and pseudo-random configurations the advantage of polarization agility and broad band operation is achieved by using a spiral antenna as radiating element. The array radiation characteristics are evaluated by resorting to the active element pattern approach in conjunction with the method of moments (MoM), so as to properly account for mutual coupling between the elements. The scanning performance of two like size 32-element pseudo-uniform and pseudo-random arrays are thoroughly compared in terms of maximum gain, half power beamwidth and side lobe level and relevant numerical results are provided. The variations with beam steering of the active reflection coefficient are also studied.
3 citations
References
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TL;DR: A number of theorems are proved to show that it always converges and that it converges rapidly, and this method has been used to solve a system of one hundred non-linear simultaneous equations.
Abstract: © The British Computer Society Issue Section: Articles Download all figures A powerful iterative descent method for finding a local minimum of a function of several variables is described. A number of theorems are proved to show that it always converges and that it converges rapidly. Numerical tests on a variety of functions confirm these theorems. The method has been used to solve a system of one hundred non-linear simultaneous equations. Related articles in Web of Science
4,305 citations
TL;DR: In this paper, the radiated far field is determined from a rapidly convergent series representation of the radiation integral, where the coefficients of the series are independent of the observation angles, and the field may be determined very rapidly at large numbers of points.
Abstract: Given the true or any approximate current on a reflector, the radiated far-field is determined from a rapidly convergent series representation of the radiation integral. The leading term is a well-shaped J_{1}(x)/x beam pointing in a desired direction. Higher order terms provide perturbations to the leading term. The coefficients of the series are independent of the observation angles. Hence, once they are computed, the field may be determined very rapidly at large numbers of points. Initially, a suitable small angle approximation is made that places the radiation integral in the form of a Fourier transform on a circular disk. The theory is then extended such that the results are valid in both the near and the wide angle regions. Application to a rotationally symmetric paraboloid is presented herein. Other applications include the offset and dual reflectors and near- to far-field integrations. A modified form of the series can also be used for Fresnel zone computations.
110 citations
01 Jan 1966
TL;DR: In this paper, the radiation properties of a spherical phased-array antenna with circularly polarized elements are studied and a special distribution of elements on a spherical surface is developed to suppress the grating lobes in the pattern and thereby makes the antenna array broadband.
Abstract: The radiation properties of a spherical phased-array antenna with circularly polarized elements are studied. Each antenna element is assumed to have a cosine type of field pattern. It is found that such an array is capable of providing complete hemispherical coverage without appreciable loss of gain. The radiation produced by the array stays circularly polarized in all directions, and the state of polarization is independent of beam steering. A special distribution of elements on a spherical surface is developed. This considerably suppresses the grating lobes in the pattern and thereby makes the antenna array broadband. Numerical calculations are made to determine the directivity and half-power beamwidth for the radiation patterns produced under various situations.
82 citations
TL;DR: In this article, a series approach for the rapid computation of the vector secondary pattern of offset paraboloid reflectors wherein the feed is displaced is presented, which has been demonstrated to provide an efficient means for evaluating the radiation integral of symmetric parabolic reflectors without compromising the ease or speed of computation.
Abstract: A series approach for the rapid computation of the vector secondary pattern of offset paraboloid reflectors wherein the feed is displaced is presented. We show that the Jacobi polynomial series method, which has been demonstrated to provide an efficient means for evaluating the radiation integral of symmetric paraboloid reflectors, can be extended to the case of an offset paraboloid without compromising the ease or speed of computation. The analysis leading to the series formula is also useful for deriving an analytic expression for the optimum scan plane for the displacement of the feed. Representative numerical results illustrating the application of the method and the properties of the offset paraboloid are presented.
75 citations
01 May 1967
TL;DR: In this article, a general formulation of the gain-optimization procedure for an array with an arbitrary geometrical configuration is presented and specialised to apply to a planar array, and extensive computed data for the maximum obtainable directive gain of circular and elliptical arrays are presented and compared with those with a uniform amplitude and cophasal excitation.
Abstract: The paper begins with a general formulation of the gain-optimisation procedure for an array with an arbitrary geometrical configuration. The formulation is then specialised to apply to a planar array. In particular, extensive computed data for the maximum obtainable directive gain of circular and elliptical arrays are presented and compared with those with a uniform amplitude and cophasal excitation. For small element separations, a supergain situation results under optimum-gain conditions. A main-beam radiation efficiency is defined, which serves as an additional performance index. In a supergain situation, a proper design represents a suitable compromise between the directive gain and the main-beam radiation efficiency.
32 citations