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Measurement of the radiation properties of low gain antennas at VHF frequency is in many cases a challenging task. Measurements performed in shielded anechoic chambers are usually preferred to outdoor ranges because they are not subject to the electromagnetic pollution and less affected by the scattering of the environment. However, different source of errors, such as truncation of the scanning surface...
Recent use of measured data as near field sources in Computational Electro Magnetic (CEM) tools has opened the possibility to represent antennas in numerical simulations, even when the antenna characteristics and geometry are unknown and therefore cannot be included in a full wave model [1-4]. The near field source consists of an equivalent current representation of the antenna, which is prepared...
The inverse source technique is an accurate post processing and diagnostics method for antenna measurements [1-3]. Indeed, this technique has proven useful to suppress and filter disturbances in measurement scenarios such as presence of the feeding cable and mounting support [4-6]. Performing accurate measurements of on-chip antennas at millimeter wave frequencies is difficult in particular due to...
The accurate characterization of low-gain antennas at VHF frequencies is challenging. Such antennas can be tested outdoors for convenience or in very large and thus expensive indoor Far-Field (FF) ranges [1]. Indoor Near-Field (NF) systems are often considered a better cost compromise for such measurements, mainly due to the relaxed requirements on chamber size. However, reflectivity issues and other...
The measured source or Huygens box antenna representation has become an increasing popular solution to create accurate computational models of measured source antennas for the numerical analysis of antenna placement on complex platforms such as satellites. The equivalent representation of the measured antenna is obtained through the equivalent current (EQC) or inverse source technique, which is a...
Probe correction in Spherical Near Field (SNF) measurements is typically performed during the NF/FF transformation assuming a probe with limited |μ|=1 spectrum [1]–[2]. This requirement leads to challenging probe designs, especially if the required bandwidth is wide. For this reason, in many practical cases, higher order spherical modes could be radiated. In this paper, the source of higher order...
Integration of antenna measurements in numerical simulations, based on the equivalent current technique, has been validated in previous activities [1–8]. A link, enabling the export of an accurate numerical model, derived from the measured antenna pattern, to a number of commercial Computational Electromagnetic (CEM) solvers has been created and validated [9–14]. The equivalent current processing...
Accurate numerical models of a given antenna can be derived from measurements using the inverse source technique [1–3]. Using this technique, measured antenna patterns can currently be imported and used as numerical sources in a number of commercial Computational Electromagnetic (CEM) solvers [4–9]. This method has been validated experimentally and the achievable accuracy investigated for both stand-alone...
Electromagnetic models of measured antenna can be accurately computed by the inverse source technique, implemented in the MVG software INSIGHT [1–5]. The measurement processing is based on the expansion of the measured field using equivalent currents [7–10]. A recently created link enable the INSIGHT to export the electromagnetic model to a number of commercial Computational Electromagnetic (CEM)...
The equivalent current (EQC) technique applied on antenna measurements has been demonstrated to be an efficient tool for diagnostics in many measurement situations [15]. Indeed the equivalent currents can be applied in tasks such as the filtering of disturbances such as undesired coupling with the supporting structure or the feeding and in NF-NF transformation. In particular the filtering capabilities...
Classical probe corrected Spherical Near Field (SNF) measurement assumes probes with limited |µ|=1 spectrum [1]–[3]. This requirements is needed to fully compensate the effect of the probe during the NF/FF transformation [3]. If the probe spectrum contains higher order modes, a residual error will affect the measured pattern (probe modal truncation). This requirement leads to challenging probe designs,...
Computational Electromagnetics (CEM) solvers are important engineering tools in the characterization and optimization of antenna placement on large and complex platforms. The accuracy of the source representation has a strong influence on the simulation accuracy of such antenna systems. It is customary to use domain decomposition technique based on the near field description of the local domain in...
In this paper data coming from a GNSS satellite measurement campaign will be used to perform an advanced analysis regarding the interaction between antennas, satellite structure and appendages.
This paper describes the application of the inversesource also named source-reconstruction technique [1–4] applied to the practical case of a space antenna intended for the European Navigation System GALILEO. The antenna (a pre-development flying on the GALILEO In Orbit Validation Element-B (GIOVE-B) satellite) consists in an array of 42 patch elements, divided into six sectors and fed by a two levels...
The equivalent radiating current technique (EQC) is based on an integral equation formulation of the inverse source problem upon rigorous application of the equivalence principle [1]–[7]. This method offers a greater generality and flexibility since it allows reconstructing sources on arbitrary 3-D surfaces enclosing the antenna under test (AUT). Indeed the equivalent source approach is a true 3D...
Coaxial cable is often used for measurements of antennas inside anechoic chambers. In the measurement of a monopole antenna with a small ground-plane, the finite-sized ground causes the current to flow back from the radiator to the outer surface of the coaxial cable. This results in secondary radiation which introduces errors to the measured radiation pattern. To reduce the unwanted secondary radiation,...
This communication presents promising applications of the integral equation formulation of the inverse source problem. The technique is based on the extraction of equivalent sources on a 3-D closed surface enclosing the Antenna Under Test (AUT) from near or far field measured radiation patterns upon rigorous application of the equivalence principle. Such sources allow malfunction detection and design...
We want to reconstruct equivalent sources on a “reconstruction surface” ΣR that encloses a volume Ω where the equipment under test (EUT) lies; the EUT encompasses the antenna(s) and possible neighboring scatterers, as need in the application of interest. We employ the equivalence theorem to represent the fields outside the reconstruction surface ΣR and on it. Note that it is typically desirable or...
This communication presents a novel technique to deal with undesired interaction of the AUT with cables and other nearby disturbances. Its key features are: i) it allows removal of the effect of disturbances on antenna pattern, ii) it requires only approximate geometrical knowledge of the AUT and disturbing objects and iii) it is a fast data post-processing step that puts no special requirements on...
This paper discuss recent advances in antenna diagnostics from measured field data. The method proposed is based on field representation using equivalent magnetic and electric sources on arbitrary shaped geometries enclosing the antenna under test. This paper briefly outlines the standard formulation and shows the need of enhancement for the general case of fully blind reconstruction. Subsequently,...
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