Sara Burgos

New Reflection Suppression Method in Antenna Measurement Systems Based on Diagnostic Techniques

A new method to reduce the unwanted reflection effects in antenna measurements is presented. The proposed method can be applied to measurements performed in semi-anechoic chambers, outdoor systems or even anechoic environments with a poor reflectivity level to remove reflected components and to retrieve the results one would obtain in an ideal anechoic chamber. The method is based on spatial filtering over the plane where the antenna under test (AUT) is placed. To calculate the field in this plane, a diagnostic technique is employed. However, in contrast to classic application (error source identification), the reconstructed field has to be obtained in a zone larger than the antenna dimensions. Thus, it is possible to identify virtual sources out of the antenna aperture, which appear due to the presence of reflections (image theory). Then, by cancelling the virtual and unwanted sources, the related reflected components can be suppressed. Finally, by employing this filtered reconstructed field, a new radiation pattern similar to the one obtained in a fully anechoic environment is calculated. To verify the effectiveness of the method, three examples are presented.

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

A method to reduce the noise power in a far-field pattern without modifying the desired signal is proposed. An important signal-to-noise-ratio improvement may thereby be achieved. The method is used when the antenna measurement is performed in the planar near-field, where the recorded data are assumed to be corrupted with white Gaussian and space-stationary noise, because of the receivers additive noise. Back-propagating the measured field from the scan plane to the plane of the antenna under test (AUT), 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, canceling the field that is located out of the AUTs dimensions and that is only composed of 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 are presented using both simulated and measured near-field data.

Overview of Novel Post-Processing Techniques to Reduce Uncertainty in Antenna Measurements

The error analysis has been investigated since 1975 since recent publications, as shown in references as (Newell et al., 1975) where the classical 18 terms for planar near field systems where established. It is also worth mentioning the more recent studies developed inside the actions under the “Antenna Measurement” activity of the “Antenna Centre of Excellence (ACE)” within the sixth framework research program of the European Union. In particular, that work pretended to establish common error calculation criteria in spherical near-field and far-field antenna measurement systems. The results of that research were summarized in an exhaustive deliverable (Alexandridis et al., 2007), which detailed the observations stated by several research institutions. In that deliverable it was agreed that the causes of uncertainties and errors in a spherical near-field antenna measurement are divided in six categories:

Compact antenna test range implementation in IETR millimetre wave antenna test facility

A Compact Antenna Test Range (CATR) has been implemented in the millimeter wave antenna test facility of the Institute of Electronic and Telecommunications of Rennes in order to improve its measurements capabilities. This paper describes the main lines of this project, from the technical requirements to the verification of the CATR capabilities. Measurements of the Quiet Zone (QZ) in V-band are presented to show the performance of this equipment.