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The purpose of this research is to improve design flexibility of array antenna operating on traveling-wave excitation. Beam direction can be controlled by phase change caused by transmitting through the periodic structure in slotted waveguide. The slot array antenna on a left-handed waveguide (LHWG) is designed in this paper. The antenna was composed of slots on a left-handed waveguide in which pairs...
The compact multimode horn for circular coverage has been developed under the optimization design method. The numerical and experimental discussions have verified that the designed coaxial cavities work well for generating circular-waveguide higher-order modes.
The application of the Method of Moments to the analysis of large PEC structures is difficult due to the computational requirements when the structure is discretized in a high number of unknowns. To solve this problem we propose the Multilevel Field Interpolation Algorithm (MLFIA) based on a source domain decomposition that permits a fast matrix-vector multiplication within the iterative solution...
This paper proposes a novel imaging architecture suited for use in the mm and the sub-mm wave regimes. The structure is composed by a one dimensional array of radiators in order to enhance the image acquisition time with respect to single element detection. Moreover each of the antenna elements composing the array is characterized by a relatively broad band which opens the possibility for the array...
In this work, a new asymptotic phasefront extraction technique, based on a different setting of the AP-IE technique is proposed.It starts from standard ("elemental") basis functions fn(r;l), with a with a typical length these are aggregated to form larger functions that include the phase information; these are used as MoM basis functions.
Widely used method of moments (MoM) (R.F. Harrington, 1993) for numerical solution of electromagnetic (EM) radiation and scattering problems is severely limited by the electrical size of the problem due to the storage requirement of O(N2) (N = number of unknowns) and the direct solution time of O(N3). The latter can be reduced down to O(IN2) where / is the number of iterations for an iterative method...
The most common preconditioners are of algebraic nature, based on sparse inverse approximations of the MoM matrix Z, like the incomplete LU decomposition (ILU). An improvement in the condition number can be also obtained directly in Z using appropriate basis functions, such as higher order basis functions, and multi-resolution techniques. The asymptotic phase integral equation method (AP-IE) is also...
To facilitate the analysis of large problems, in this paper, all the full matrices are stored in a sparse form and the PFFT method is employed to accelerate all the matrix-vector products appearing in both hand sides of the matrix equation for the moments. The present method can deal with much larger problems than the traditional MoM-AWE method since the PFFT achieves great reduction in memory requirement...
Integral equation-based numerical models provide an important tool for the analysis and design in a variety of application areas. Traditional implementations of IE-based models lead to dense matrices, and this significantly limits the range of problems that can be addressed using such approaches. To treat more complex problems, it is necessary to use more sophisticated methods which rely on compressed...
Reconfigurable feature offers electronic control of each element which provides for easier implementation of the whole reflectarray system. Several potential reflectarray element designs were investigated with critical importance given to the consideration of MEMS implementation in the final design. The reflectarray element with variable slot on ground plane and fixed patch on top was selected for...
A novel reconfigurable single layer microstrip antenna fed using a coplanar waveguide through a cross-slot coupling combination range to achieve polarization diversity is investigated in the millimeter-wave. The cross-slot coupling combination allows for easy reconfigurability of the polarization diversities by incorporating switches in the feed network. The polarization diversity is obtained by switching...
This work presents a method to determine the required discrete surface distortions to correct errors. The algorithm starts by discretizing the entire reflector surface into triangular patches then by finding a linear relationship between the local distortion and the difference of the distorted and undistorted far fields patterns. A linear system of equations with the distortions as unknowns results...
In this paper, we proposed the multi element PIFA with an enhanced gain characteristic. It is 35 times 15 times 5 mm3 in size so that it can be put in the A-model handset case of the S-company. The radiator of the antenna is divided into 4 elements to obtain the antenna with high gain characteristic. The divided antenna can obtain enhanced gain characteristic as currents are uniformly distributed...
The design, microfabrication, and characterization of a multifunctional reconfigurable antenna (MRA), so called MRA annular slot, capable of changing its operating frequency are presented. Frequency reconfigurability is achieved through microelectromechanical systems (MEMS) actuators strategically located within the antenna architecture.
A star antenna with four symmetrical feeding points is proposed for switched beam applications. The feeding points are located on the four apexes of its 8 arms and when excited one by one, generate four tilted beams of the same characteristics in different quadrant, thus yielding a beam steerable antenna. Also, the return losses of the antenna under different feed configurations remain the same. The...
A novel beam switching antenna design is proposed in this work. This antenna uses a dipole as the fed and a cylindrical metal enclosure with a stack of circular slits is put around dipole. An array of RF switches made of pin diodes are placed across the slits. The antenna beam can be adjusted to the desired direction by changing on-off states of the switches, which in turn reconfigures the slot array...
This paper describes the design, fabrication, and characterization of a large scan angle FSS comprised of a periodic array of dielectric-filled tapered holes as shown in Figure 1(a). The performances of three FSSs with different taper profiles and equal hexagonal lattices are compared. FSSs with cylindrical, linearly tapered, and cosine tapered holes (Figure 1(b)) show dramatically different TE and...
This paper extends these initial efforts and attempts to increase the transmission and bandwidth by using multiple meanderline layers. A new ellipsometric method of characterization allows spectral measurements from 6-14 mum. The use of multiple layers reduces impedance mismatches at each meanderline layer. Therefore less reflection is seen at each interface. A dielectric superstrate layer is also...
To increase the capabilities of multifunction and multifrequency antennas, a frequency selective surface should also be designed to operate over multiple frequency bands.This paper deals with the scattering of a plane wave incident upon a two-dimensional periodic array of multiple conducting plates with different lengths. It is well known that the plate length is roughly half a wavelength where the...
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