Novel Method to Improve the Signal to Noise Ratio in the Far-field Results Obtained from Planar Near Field Measurements.

A method to reduce the noise power in far-field pattern without modifying the desired signal is proposed. Therefore, an important signal-to-noise ratio improvement may be achieved. The method is used when the antenna measurement is performed in planar nearfield, where the recorded data are assumed to be corrupted with white Gaussian and space-stationary noise, because of the receiver additive noise. Back-propagating the measured field from the scan plane to the antenna under test (AUT) plane, the noise remains white Gaussian and space-stationary, whereas the desired field is theoretically concentrated in the aperture antenna. Thanks to this fact, a spatial filtering may be applied, cancelling the field which is located out of the AUT dimensions and which is only composed by noise. Next, a planar field to far-field transformation is carried out, achieving a great improvement compared to the pattern obtained directly from the measurement. To verify the effectiveness of the method, two examples will be presented using both simulated and measured near-field data

Application of sources reconstruction techniques: Theory and practical results.

In this paper, four new applications of sources reconstruction techniques (also called diagnostic techniques) are presented. First of all, the important information of such techniques will be mentioned, seeing that they are a tool to obtain the extremely near field from the measured data. Depending on the region where these data are taken (near field or far field), the reconstruction method will be different. Also, all of them may be classified in other two groups depending on its features: Integral Equation Methods (IEM) or Modal Expansion Methods. Classical applications of such techniques are errors detection, like phase errors in arrays or conformai errors in reflectors, therefore, they constitute an important antenna design tool. But also and it has been said, they can be used as the basis to other applications whose aim is to improve the measurement results in anechoic chambers or non anechoic environments. Here, four of them are presented, being the reflection cancelling, the detection of unwanted radiation points, the truncation error reduction in planar or cylindrical near-field and the noise reduction

Resistance acquisition after seven cycles of in vitro bleomycin exposure

Bleomycin is an antineoplastic drug that causes DNA damage by intra- and inter-strand crosslink and DNA strand breaks. This drug is used to treat several types of cancer. The aim of this work is to study the effect of Bleomycin on S. cerevisiae cells and select bleomycin-resistant cells to study the process of resistance acquisition to establish new protocols in in vitro drugs exposure.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Selection of resistance to cisplatin in saccharomyces cerevisiae as a model for antineoplastic drugs studies

The budding yeast (S. cerevisiae) is an excellent eukaryotic model to study the antineoplastic drugs effects, due to the well-characterized metabolic and genetic characteristics and the conserved similarity in molecular mechanisms with other species including human cells. The aim of this work is to study the effect of cisplatin on S. cerevisiae cells and select cisplatin-resistant cells of this organism as a model of study of resistance to antineoplastic drugs.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Applications of the Diagnosis Techniques in Antenna for the Reduction of the Measurements Errors

This paper shows several applications of the diagnostic techniques for the reduction of some error or uncertainty factors in antenna measurements. The method is based in the calculation of the extremely near field from the far field using FFT (Fast Fourier Transform) Techniques, improved with the Gerchberg-Papoulis Algorithm. The classical applications of the diagnostic techniques are errors detection, like phase errors in arrays or conformal errors in reflectors. Therefore, they constitute an important antenna design tool. Also, they can be used for other applications whose aim is improve the measurements in anechoic chambers. This paper shows different process applied to reduce the effect of the reflections, the effect of the leakage from AUT (Antenna under test), to improve the signal to noise and to reduce the truncation error in the planar or cylindrical near field

Error Analysis and Simulator in Cylindrical Near-Field Antenna Measurement Systems

Large antennas need special measurement systems because of their considerable dimensions. Typically, cylindrical near-field systems are appropriate measurement systems for omnidirectional antennas due to the characteristics of their radiation patterns. Furthermore, these systems are also appropriate for sizeable RADAR antennas, since they can be measured on their azimuthal positioner and the probe can be easily translated through a vertical linear slide. Thus, mechanical aspects of measurement systems are rather important since errors in the mechanical set-up can directly affect far-field radiation patterns. This chapter presents an error estimation tool to analyze the most important errors for large L-band RADAR antennas in an outdoor cylindrical acquisition system and the effect of these errors in the calculated far-field radiation pattern. This analysis can be very convenient to evaluate the error budget of the Antenna Under Test (AUT). The simulator computes the far-field with an array of vertical dipoles over a ground plane and compares an ideal infinite far-field with the electric field obtained using the cylindrical near-to-far-field (NF-FF) transformation algorithm. The influence of the inaccuracies on the final results is evaluated by introducing random and systematic sources of errors and then, analyzing the variations produced in the principal far-field patterns, antenna parameters and in the side lobe levels (SLL). Finally, this simulator can be employed to analyze the errors for L-band RADAR antennas. One of the objectives of this investigation is thus to analyse how mechanical and electrical inaccuracies could affect the results of a cylindrical antenna measurement system, in order to minimize them as much as possible. This is highly important not only to meet the specifications, but also to reach high accurate results. There are several error sources studies for near-field patterns: the most complete are the ones developed by Joy and Newell in [Joy, 1988], [Newell, 1988], [Newell & Stubenrauch, 1988] and Hansen in [Hansen, 1988]. Later on, other investigations have been carried out analyzing precise error studies. Another goal is the a-priori uncertainty analysis of these errors in the measurement of Lband RADAR antennas, detecting which are the main error sources for each antenn

Aplicación de técnicas de diagnóstico de antenas para aumentar el margen visible y cancelar reflexiones

A new method of array antenna diagnosis is proposed. The method uses far field information which it is possible to reconstruct the excitations of the elements and the field over the aperture of the array antennas, providing the module and the phase. A simple study of this module and this phase can detect errors, for example, errors in the alignment of the phase, connections or general structure of the array antennas. So, without a similar technique for antenna diagnosis, it would be necessary to check that elements, connections or structure. Therefore, when there are a lot of elements it would be a waste of time

Electrical and mechanical uncertainty study in cylindrical near field antenna measurement systems

In order to evaluate how mechanical or electrical errors may affect in the final results (i.e. radiation patterns, directivity, side lobe levels (SLL), beam width, maximum and null position…), an error simulator based on virtual acquisitions of the measurement of the radiation characteristics in a cylindrical near-field facility has been implemented [1], [2]. In this case, the Antenna Under Test (AUT) is modelled as an array of vertical dipoles and the probe is assumed to be a corrugated horn antenna. This tool allows simulating an acquisition containing mechanical errors – deterministic and random errors in the x-, yand z-position – and also electrical inaccuracies – such as phase errors or noise –. Then, after a near-to-far-field transformation [3], by comparing the results obtained in the ideal case and when including errors, the deviation produced can be estimated. As a result, through virtual simulations, it is possible to determine if the measurement accuracy requirements can be satisfied or not and the effect of the errors on the measurement results can be checked. This paper describes the error simulator implemented and the results achieved for some of the error sources considered for an L-band RADAR antennas in a 15 meters cylindrical near field system

Uncertainty simulator to evaluate the electrical and mechanical deviations in cylindrical near field antenna measurement systems

In order to evaluate how mechanical or electrical errors may affect in the final results (i.e. radiation patterns, directivity, side lobe levels (SLL), beam width, maximum and null position…), an error simulator based on virtual acquisitions of the measurement of the radiation characteristics in a cylindrical near-field facility has been implemented [1], [2]. In this case, the Antenna Under Test (AUT) is modelled as an array of vertical dipoles and the probe is assumed to be a corrugated horn antenna. This tool allows simulating an acquisition containing mechanical errors – deterministic and random errors in the x-, y- and z-position – and also electrical inaccuracies – such as phase errors or noise –. Then, after a near-to-far-field transformation [3], by comparing the results obtained in the ideal case and when including errors, the deviation produced can be estimated. As a result, through virtual simulations, it is possible to determine if the measurement accuracy requirements can be satisfied or not and the effect of the errors on the measurement results can be checked. This paper describes the error simulator implemented and the results achieved for some of the error sources considered for an L-band RADAR antennas in a 15 meters cylindrical near field syste