Antenna Physical Poles Extracted From Measured Backscattered Fields

Abstract

International audienceThis paper presents a new approach to extract the physical poles of antennas. The Singularity Expansion Method (SEM) allows modelling the antenna backscattering using poles which are theoretically independent of the wave incident angle, making them useful for antenna identification. Nevertheless, only the physical poles respect this property while the spurious poles change for each incident angle. Indeed, we call physical the poles linked to the antenna itself and spurious the poles linked to anything but the antenna (excitation, noise…). The goal of this paper is to highlight the method to define the optimal time windowing applied on the antenna backscattering in order to obtain the physical poles of the antenna. The approach is based on the Window Decreasing Technique and the Window Increasing Technique. The SEM is applied on the backscattered field measured in the boresight direction of three antennas: a narrowband patch antenna, a wideband helix antenna and a UWB antenna. By using these poles to reconstruct the field backscattered in several directions, we show that the poles extracted from one direction with this new approach are relevant to reconstruct the backscattered field for any other directions. Moreover, we show that these poles can be extracted directly from these other directions

Accurate Characterization of Reverberation Chamber Resonant Modes From Scattering Parameters Measurement

“…We propose to use the Window Increasing Technique (WIT) [35], [38] in order to filter out the spurious poles. This technique is derived from the window moving technique already introduced in target identification [39], RFID interrogation [40], and antenna characterization [29]. The principle of the WIT is presented in Fig.…”

“…Although it is quite simple for the noiseless case, it becomes much more challenging once dealing with noisy data. Indeed, for such noisy cases, the extracted poles are a mix between the true poles, the ones with a physical meaning, and the spurious poles, the ones only due to the presence of noise [29]. Thus, if we set the number of poles N to be extracted to the exact number of true poles, the extraction of one spurious pole leads consequently to the non-extraction of one true pole.…”

Sensitivity of the singularity expansion method applied on dipole antenna backscattering

“…Indeed, it is shown in [5] that resonant poles correspond to the natural resonances of antennas, especially for narrow band ones. Moreover, we know that poles can be extracted from antenna backscattered field and these poles are similar to those extracted from the radiated field [6]. The objective of this paper is to look at the sensitivity of the SEM regarding the antenna considered in order to be able to discriminate two antennas with close dimensions.…”

Mode-Stirring Impact in Radar Cross Section Evaluation in Reverberation Chamber

“…Radar Cross Section (RCS) is the commonly used parameter to describe the scattering behavior of an object. It is of interest in a wide range of topics including stealth optimization, radar detection, RFID interrogation [1] and antenna characterization [2]. Its determination is usually obtained thanks to S11-parameters measurement performed in a large anechoic chamber.…”