Modeling and synthesis of circular-sectoral arrays of log-periodic antennas using multilevel fast multipole algorithm and genetic algorithms

Circular-sectoral arrays of log-periodic (LP) antennas are presented for frequency-independent operation and beam-steering capability. Specifically, nonplanar trapezoidal tooth LP antennas are considered in a circular array configuration, where closely spaced antennas occupy a sector of the circle. Electromagnetic interactions of the array elements, each of which is a complicated LP antenna structure, are rigorously computed with the multilevel fast multipole algorithm (MLFMA). Genetic algorithms (GAs) are also employed in combination with MLFMA for synthesis and design purposes. By optimizing the excitations of the array elements via GAs, beam-steering ability is achieved in addition to the broadband (nearly frequency-independent) characteristics of the designed arrays. Computational results are presented to demonstrate the important properties of LP arrays.


Nonplanar trapezoidal tooth log-periodic antennas: Design and electromagnetic modeling
Ergül, Özgür Salih (American Geophysical Union (AGU), 2005-10-18)
Nonplanar trapezoidal tooth log-periodic (LP) antennas are investigated by combining the wisdom of theoretical design procedures with the power of accurate numerical simulation environments. Once the theoretical design is completed, electromagnetic simulations employing accurate integral equation solvers are utilized to test and correct the original design. A two-element array of trapezoidal tooth LP antennas is designed. The array features beam-steering ability as a novelty, in addition to frequency indepe...
Sectorized approach and measurement reduction for mutual coupling calibration of non-omnidirectional antenna arrays
Aksoy, Taylan; Tuncer, Temel Engin (American Geophysical Union (AGU), 2013-03-01)
Mutual coupling calibration is an important problem for antenna arrays. There are different methods proposed for omnidirectional antennas in the literature. However, many practical antennas have non-omnidirectional (NOD) characteristics. Hence, the previous mutual coupling calibration methods cannot be applied directly since the mutual coupling matrix of an NOD antenna array has angular dependency. In this paper, a sectorized approach is proposed with a transformation matrix for mutual coupling calibration ...
Performance of IRI-based ionospheric critical frequency calculations with reference to forecasting
ÜNAL, İBRAHİM; Senalp, Erdem Turker; YEŞİL, ALİ; Tulunay, Ersin; Tulunay, Yurdanur (American Geophysical Union (AGU), 2011-01-27)
Ionospheric critical frequency (foF2) is an important ionospheric parameter in telecommunication. Ionospheric processes are highly nonlinear and time varying. Thus, mathematical modeling based on physical principles is extremely difficult if not impossible. The authors forecast foF2 values by using neural networks and, in parallel, they calculate foF2 values based on the IRI model. The foF2 values were forecast 1 h in advance by using the Middle East Technical University Neural Network model (METU-NN) and t...
Uniform and nonuniform V-shaped planar arrays for 2-D direction-of-arrival estimation
Filik, T.; Tuncer, Temel Engin (American Geophysical Union (AGU), 2009-09-22)
In this paper, isotropic and directional uniform and nonuniform V-shaped arrays are considered for azimuth and elevation direction-of-arrival (DOA) angle estimation simultaneously. It is shown that the uniform isotropic V-shaped arrays (UI V arrays) have no angle coupling between the azimuth and elevation DOA. The design of the UI V arrays is investigated, and closed form expressions are presented for the parameters of the UI V arrays and nonuniform V arrays. These expressions allow one to find the isotropi...
Fabrication of 15-mu m Pitch 640 x 512 InAs/GaSb Type-II Superlattice Focal Plane Arrays
Oguz, Fikri; Arslan, Yetkin; Ulker, Erkin; Bek, Alpan; Ozbay, Ekmel (Institute of Electrical and Electronics Engineers (IEEE), 2019-08-01)
We present the fabrication of large format 640 x 512, 15-mu m pitch, mid-wave infrared region (MWIR) InAs/GaSb type-II superlattice (T2SL) focal plane array (FPA). In this report, the details of device design and fabrication processes are withheld adhering to the common practice of most of the manufactures and developers because of the strategic importance; however, information about fabrication processes of T2SLs FPA is presented to a certain extent. Comparison of etching techniques, passivation materials ...
Citation Formats
Ö. S. Ergül, “Modeling and synthesis of circular-sectoral arrays of log-periodic antennas using multilevel fast multipole algorithm and genetic algorithms,” RADIO SCIENCE, pp. 0–0, 2007, Accessed: 00, 2020. [Online]. Available: