Design and realization of a dual band, dual polarized composite monopulse tracking feed, covering S-(2.0-2.3 GHz) and X-band (7.8-8.5 GHz) is reported in this article. X-band feed is a five element monopulse feed, comprising a corrugated horn acting as the main or Sum element surrounded by four circular septum polarizers serving as tracking elements. S-band feed is a four element monopulse feed consisting of square dielectric array arranged in 2×2 configurations. Illumination efficiency of the proposed composite feed, positioned in the same Cassegrain plane, is above 90 % for both the bands. S/X composite feed is systematically designed, fabricated and experimentally characterized revealing excellent correspondence with the simulated result. The realized composite feed is installed in 7.5m antenna system at NRSC Hyderabad, ISRO, India and currently fully operational. Expected / targeted G/T of 32 dB/K is achieved with the realized antenna system. The proposed feed is highly efficient, compact, simple and costeffective, uses generic design style and perfectly suitable as ground station reflector feed antenna, meeting stringent industry specification.INDEX TERMS Monopulse feed, dual band, corrugated horn, circular septum polarizer, cassegrain, secondary pattern.
Linear-array of circular split ring resonators (C-SRR) integrated wideband notched filtering horn antenna with very strong rejection-band is proposed in this article. The linear C-SRR array, consisting of 3-sub arrays each having 4 identical C-SRR-elements, is printed on a dielectric substrate and is integrated into the throat or waveguide-section of the standard X-band horn (Narada 641). Staggered arrangement of the multiple C-SRRs based in-line filter contributes to the wideband notch filtering response with measured rejection band (S11< 3-dB) of 315 MHz in proposed horn-filtenna. The realized horn-filtenna yields co-and cross-polar peak gain suppression of 35.42 dB and 24.6 dB at and around the centre of notch-band (9.8 GHz) while at the pass band of the C-SRR filter, the proposed antenna inherits the impedance and radiation characteristics of the standalone horn antenna. The proposed technique is simple, easy to integrate and can be used to eliminate adjacent band noise/interference for faithful reception of data without using any additional filter section.
Feature selection is the process of identifying statistically most relevant features to improve the predictive capabilities of the classifiers. To find the best features subsets, the population based approaches like Particle Swarm Optimization(PSO) and genetic algorithms are being widely employed. However, it is a general observation that not having right set of particles in the swarm may result in sub-optimal solutions, affecting the accuracies of classifiers. To address this issue, we propose a novel tunable swarm size approach to reconfigure the particles in a standard PSO, based on the data sets, in real time. The proposed algorithm is named as Tunable Particle Swarm Size Optimization Algorithm (TPSO). It is a wrapper based approach wherein an Alternating Decision Tree (ADT) classifier is used for identifying influential feature subset, which is further evaluated by a new objective function which integrates the Classification Accuracy (CA) with a modified F-Score, to ensure better classification accuracy over varying population sizes. Experimental studies on bench mark data sets and Wilcoxon statistical test have proved the fact that the proposed algorithm (TPSO) is efficient in identifying optimal feature subsets that improve classification accuracies of base classifiers in comparison to its standalone form. 1
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