Fully Probe-Corrected Near-Field Far-Field Transformations With Unknown Probe Antennas

Abstract

According to the electromagnetic uniqueness theorem, the radiation behavior of an antenna under test (AUT) can be recovered from measurements of two tangential components of its radiated fields on an enclosing surface. In practice, measurements conducted in the radiating near-field (NF) of an AUT utilize probe antennas of finite size. Thus, instead of discrete field values, spatially blurred probe signals are acquired. The probe influence can be compensated, however, this commonly requires precise knowledge about the probe antenna. In this work, the concept of NF far-field (FF) transformations (NFFFTs) with full correction of the influence of unknown probe antennas is introduced. Two nonconvex and two convex formulations are presented and their relation to the similar task of phase retrieval is highlighted. Simulation and measurement results illustrate the validity of the concept, shed light on the required complexity of measurement setups, and illustrate limitations of the approach. Special attention is paid to the case of high practical relevance when AUT and probe are identical.

A New Technique for Broadband Matching of Open-Ended Rectangular Waveguide Radiator

“…Since the first experiment in 1900 by Flemming [1] and the first scientific theory in 1938 [2], the rectangular waveguide open-end radiator, as one of the canonical radiating elements, has been used in a wide range of applications, including near-field antenna measurement [3][4][5][6][7][8][9], dielectric material characterization [10,11], electric field measurement [12,13], array antennas [14][15][16], electric field probe calibration [17], feeding a reflector antenna [18], non-destructive testing [19][20][21], imaging sensors [22] and the excitation of various radiating elements [23][24][25][26]. A comprehensive review of various open-ended waveguides has been presented in [27].…”

Near-Field-to-Far-Field RCS Prediction Using Only Amplitude Estimation Technique Based on State Space Method

“…Therefore, predicting a FF RCS from an NF extrapolation is an important research area. Recent studies have demonstrated that by processing the scattered EM field detected by a scanning probe around the target in the NF region, NF-to-FF transformation [1][2][3][4] (NFFFT) technology can predict the target's RCS in other regions.…”