Efficient and Accurate hybrid GO-Spectral Algorithm to Design Conformal Serrated-Edge Reflectors Operating as Collimators in Millimeter Wave Compact Ranges

This paper presents a hybrid analysis algorithm, which is used at Radiation Group (UPM) to carry out the design of a conformal serrated-edge reflector for the mm-Wave compact range UPM facility. Main features of this algorithm involve its capability of handling conformal serrated rim parabolic reflectors, accuracy and computational efficiency

Antenna Measurement System at 300 GHz for the Terasense Project

The aim of this paper is to introduce the design techniques used to develop the antenna measurement system for the Terasense Project. This project, funded by the Spanish Government, involves millimetre-wave systems design. One of these systems is an antenna measurement facility. The antenna measurement system operates in a banded range of frequency. The lower frequencies deal between 75–110 GHz (WR10 operation range) and the upper frequencies are set between 220–325 GHz (WR03). Among the different possible configurations, the reflector-based compact range is chosen. The quiet zone is generated by a serrated-edge reflector, fed by a low gain horn. In this paper we will focus on the reflector design. A serrations study is carried out and quiet zone acquisition results are obtained

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

Aperture Field Reconstruction by Calculated Cylindrical Near Field

An approximate general formula to calculate the directivity of an array of antennas by a cylindrical near field acquisition is proposed. We demonstrate the role of and scan area truncation effects. The derivation is based on the theory of cylindrical wave expansion of electromagnetic fields

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

An Agent Oriented Analysis and Modeling of Airborne Capabilities for Trajectory Based Operations

Current and future air traffic is requiring new procedures and systems to achieve a greater automation of air-traffic operations. Particular difficulty presents the automation of arrival air-traffic operations in terminal areas due to aircraft speeds and environment variability into a delimited airspace where multiple aircraft converge. Several projects have proposed guidelines to implement new operational concepts as well as airborne and ground systems to carry out corresponding procedures. Developing procedures and systems are closely related. Therefore, usually it requires to analyze and to design them in a combined manner. In this paper we present an agent-oriented analysis and modeling of airborne systems capabilities to perform automated arrival and approach procedures based on user preference trajectories. A detailed architecture model of airborne capabilities is achieved through a methodological analysis of an arrival traffic scenario within the trajectory based operations paradigm

Designing a Cockpit Functionalities Architecture for Trajectory Based Operations

Trajectory Based Operations (TBO) will require new procedures and systems to achieve a suitable automation of air traffic operations. Procedures and systems for automated operations are closely related and therefore frequently they need to be modeled in a combined way. Our group is currently employing recent agent-oriented methodological approaches to obtain conceptual models about TBO scenarios. Conceptual models define roles of air traffic entities as well as their interactions together with a detailed description of the entities’ architecture and dynamic behaviour. In this paper we present a cockpit functionality architecture built upon a methodological analysis and design of a TBO scenario as a multi-agent system. The proposed design has the advantage of mapping to an executable model for analytical simulation of TBO concepts and its modular architecture allows for a progressive integration of additional underlying models with specific functionalities

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

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