A method for producing a shaped contour radiation pattern using asingle shaped reflector and a single feed

Eliminating the corporate feed network in shaped contour beam antennas will reduce the expense, weight, and RF loss of the antenna system. One way of producing a shaped contour beam without using a feed network is to use a single shaped reflector with a single feed element. For a prescribed contour beam and feed, an optimization method for designing the reflector shape is given. As a design example, a shaped reflector is designed to produce a continental-United-States (CONUS) coverage beam. The RF performance of the shaped reflector is then verified by physical optics     

Compensation of reflector antenna surface distortion using an arrayfeed

Various aspects of reflector surface distortion compensation are explored by first assuming the reflector distortion is given and then designing the compensating feed array. The sensitivity of boresight directivity to changing surface distortion parameters for fixed feed-array geometries is examined. It is found that feed array compensation is feasible only for distortions with low spatial frequency content, such as those distortions induced by thermal and gravitational effects. The optimum directivity methods for determining element excitation is found to yield slightly better values of directivity than those for the conjugate field matching (CMF) technique. However, the CFM technique has, in general, much lower sidelobe levels and lends itself to simple realization in hardware. In view of these results, distortion compensation using an array feed is concluded to be a reasonable approach to improving antenna performance for large, space-based reflector antennas that are not easily accessible for tuning and have time-dependent surface distortions     

Porosimetry studies on polyacrylic acid-ZnO cements

The porosity of ZnO-polyacrylic acid (PAA) composites was studied by mercury intrusion porosimetry and scanning electron microscope. There seems to be a dependence of the porosity on the ZnO/PAA ratio and a particular value for which the pore volume is a minimum. These results are analysed and explained in terms of the reaction kinetics.     

Odor learning, recall, and recognition memory in young and elderly adults.

Use of an odor learning test and the California Verbal Learning Test in young and elderly adults enabled comparison of age-related effects on recall and recognition memory. Assessment of odor identification further enabled study of which odor function (recall, identification, recognition) is most affected by aging, the odor functions' interrelationships, and predictors of odor recall. Results suggested that both recall and recognition were significantly affected by aging and that the odor-recall decline cannot simply be referred to poor identification. Very similar age-related effect sizes were found for the 3 types of odor functions. Finally, the combined ability to encode, store, and retrieve odors appears to predict overall recall performance (including its identification component) better than do identification and recognition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Radiation characteristics of microstrip arrays with parasitic elements

The radiation characteristics of microstrip antennas consisting of one centre-fed patch and several identical parasitic patches are studied experimentally. The configurations investigated include a five-element cross and three- and seven-element linear arrays. A significant increase in gain is obtained by using close interelement spacing, with no degradation in pattern characteristics.     

Preparation and evaluation of fish portions from shrimp by-catch

Fish portions were obtained from a mixture of fish flesh from shrimp by-catch. Physical, chemical, microbiological and sensory tests were done to evaluate quality of raw materials, formulations and processing conditions. Several technological procedures proved to be feasible for this product. Stability of frozen products for four months was determined by physical, chemical and microbiological tests, the results of which indicated its stability during the study period. Findings of our study, therefore, suggest the potential of shrimp by-catch for the preparation of fish portions in view of its high acceptability and simple processing technique, by using marine resources not fully utilized at present.