Correlate measurements at different test sites

The measurement of radiated emission (RE) in an anechoic chamber becomes very challenging at high frequencies, up to 60 GHz, because the scanning plane of the receiver is in measurement standard deviation from the actual wavefront. As a result, the RE intensity of the devices may be underestimated, resulting in electromagnetic interference. The deviation between the electric field at the far-field vertical scanning point and the actual wavefront is researched. Then, in an anechoic chamber, a hybrid deep learning amendment model of convolutional neural network (CNN) and transformer is proposed to correct the RE measurement at a 3 m distance. The results indicate that the correction is reliable, with an average error of 6.35% for a 3 m distance in a semianechoic chamber and less than 4.83% for other test scenarios. The proposed method provides a promising solution for RE measurement at a millimeter wave band in an anechoic chamber.

In this paper we look into a near-field measurement setup consisting of a cylindrical reflector and a linear array feed. The main application is Random Line-Of-Sight Over-The- Air measurements in anechoic or semi-anechoic chambers (i.e., anechoic chamber with reflecting floor). More specifically, the aim is testing the wireless communication systems on automotive vehicles. The aim is to generate the uniform field distribution of a plane wave over a pre-defined test zone containing the car or at least the part of the car containing the antenna(s). The field intensity variations over the testing zone have been investigated for reference measurements over the testing frequency bandwidth, i.e., 1.6–2.8 GHz.

Antenna measurements in anechoic chambers are increasingly carried out using special field strength probe (mainly for antenna measurements in the near field using the holographic method), the characteristics of which have a great influence on the accuracy of the measurement results. Therefore, in the case of using field strength probe in the measurement process, it is necessary to calibrate them and evaluate the extended error in order to increase the measurement accuracy and improve the measurement repeatability, which ultimately makes it possible to manufacture antenna devices with high characteristics. The article discusses methods for measuring the uncertainty sources that have the greatest impact on the accuracy of measurements in anechoic chambers, their numerical values and ways to deal with them. Also, the characteristics of the radar absorbing material and the configuration of the anechoic chamber itself have a significant impact on the value of the total uncertainty. A method for calculating the total uncertainty is shown.

The aim of this work is to put forward a new method for systematic retrieval of results obtained in an anechoic chamber from results measured in a semi anechoic chamber. The strategy employed is to identify the different propagating components, viz., the direct and the reflected wave components using the generalised pencil of function method. Once identified, the reflected component can be removed.

Performance improvement of a planar antenna array system has been proposed, focused in give a solution to novel satellite applications that are looking for deploy a big network of small low orbit satellites, routing data by hopping inter satellites through the shortest path. The need of having onboard low profile, high gain antenna system dynamically orientable from one to other satellite with strict constraints of weight and volume make of this an excellent challenge where apply this metamaterial approach. Simulation results with FEKO software has been compared with measurements in semi anechoic chamber.

A novel dual-band textile hexagonal AMC design covering the entire 2.5/5.5 GHz WiFi bands for wearable applications is presented through FEM simulations and reflection coefficient phase measurements in anechoic chamber. The designed structure shows polarization-angle independence under normal incidence and its angular stability under oblique incidence is also analyzed.

Radar scattering amplitudes contain pole singularities whose importance was recognized in the context of the Singularity Expansion Method: S.E.M. This method uses the fact that the late time domain response rt(t) of a target, illuminated by an E.M. wave, is mainly defined in a frequency band corresponding to the resonance region of the object. The knowledge of the singularities is useful information for discrimination of radar targets and has been used for different purposes of discrimination and identification. In this paper, we propose a modified scheme of radar target identification. The method presented is based on E-Pulse technique. In practical cases, direct application of classical E-Pulse techniques is not very efficient. Its performances are damaged by the characteristics of the exciting signal (antenna output signal). We propose a modified scheme of E-Pulse technique, which allows more accurate target discrimination and improves radar target identification. This procedure requires the deconvolution of the target response by the antenna signal and the application of an equivalent gaussian impulse excitation. This process has been successfully tested to FDTD simulations and measurements in anechoic chamber. 40 Toribio, Saillard, and Pouliguen

This paper presents a theoretical model to extract the orientation of any scatterer under normal incidence. Analytical expressions are given for mono-static configuration in co-polarization and can easily be extended in crosspolarization. The proposed approach is particularly interesting to determine chipless tag orientation, i.e., to use a chipless tag as an orientation sensor. Since the method is valid for any scatterer, antenna mode do not have to be separated from the structural mode before estimation, thus the proposed approach can directly be applied on raw signal without time gating. Measurements in anechoic chamber are done to evaluate the performance of the proposed solution.

This paper concerns the comparison between reverberation chamber (RC) and anechoic chamber (AC) measurements: In particular, the case of an immunity test is considered. A two-wire transmission line is adopted as a device under test (DUT), and the current induced on the line by the external field is monitored to construct a possible susceptibility profile. Both the averaged current over stirrer rotation and the maximum current are considered to show how robust the RC measurement is against the positioning and the orientation of the DUT inside the chamber. As expected from theory, the maximum value is related to the average one by means of the number of the independent positions of the stirrer. Finally, it is highlighted how in the RC it is possible to lose some worst case situations, related to a particular incident field polarization and incoming direction, and the underestimation of the induced current depends upon the chosen number of stirrer positions

This paper presents the design and implementation of a complete receiving smart antenna system. By using software radio techniques, the system can be re-programmed to meet different modulation standards. The platform consists of antenna array, RF module, digital IF module and digital signal processing module. Digital beam-forming and demodulation algorithms are all Implemented on DSP. Experimental results are shown for both anechoic chamber and outdoor measurements.

The measurement of an antenna in a reverberant or semi-anechoic chamber, or even in an anechoic chamber with non-ideal absorbing material, will include the effects of multipath propagation, which will be evident in a distorted radiation pattern. In those situations, an improvement of the measurement can be achieved through removal or compensation of the undesired contributions. A simple technique to eliminate those contributions, based on the well-known Fourier transform algorithm, is used in this paper. It starts from measurements of the system's response in the frequency domain, followed by Fourier transformation of data to the time domain, detection and gating of undesired echoes in the time domain, back to the frequency domain, and retrieval of the antenna radiation pattern at the frequency of interest. The method is evaluated under different measurement conditions.

The deterministic correlation of a fully anechoic chamber and open-area test-site (OATS) measurements is considered by experimental and theoretical methods using a spherical dipole antenna. The geometrical optics (GO) technique is employed to evaluate reflected waves from electromagnetic absorbers lined in the chamber. Results show that the experimental correlation factor agrees with the theoretical one within ±5 dB. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 25: 145–149, 2000.

Radiated emission test in a FAR (Fully Anechoic Room) site has been adopted as the latest version of CISPR32, IEC61000-6-3 and IEC61000-6-4 standards. Test in a FAR site without metal ground plane is expected to the measurement time reduction, since the height scan is not required to find the maximum emission because there is no reflective wave from the floor. Consequently, the severe limit of 5 dB than a test in OATS (Open Area Test Site) / SAC (Semi Anechoic Chamber) has been introduced to a test below 1 GHz in FAR. However, based on the comparative simulation results, the radiated emission limit in FAR site has been relaxed to plus 7 dB at 30 MHz from the 5 dB severe value at 230 MHz linearly with respect to the logarithm of the frequency, since the disturbance source in the equipment is affected by a metal ground plane of the test in OATS/SAC. The rationale of FAR test limit was indicated as a calculation result, but actual measurement data are not enough. Under this situation, we have performed comparison experiment measurement between SAC site and FAR site by using a same equipment to investigate the validity of the relaxed limit based on the calculation. From the experiment measurement result, the limit according to the polarization plane should be specified because it has a high possibility to mislead the product conformity assessment in a polarization of vertical to the ground plane.

An efficient method to analyze the electromagnetic field inside rectangular anechoic and semianechoic chambers from 30 to 100 MHz is shown. A modal expansion is employed to develop the homogeneous and the inhomogeneous field. This is combined with circuital techniques to compute the effect of the layers of ferrite and dielectrics in the walls of the chamber. Several numerical results of the Free Space Transmission Loss (FSTL) of an anechoic chamber and the Normalized Site Attenuation (NSA) of a semianechoic chamber are provided.

Radiated emissions measurements are commonly performed in open area test sites (OATS), anechoic and semi-anechoic chambers, and GTEM and TEM cells. The OATS test results are typically regarded as the reference standard and all other techniques must be correlatable to the OATS data. The accepted procedures all determine the maximum emissions within some defined solid angle. Reverberation chambers, which measure total radiated power, are not currently accepted in any emission standard. Simple probing of general directional emission patterns can demonstrate what fraction of the total equipment-under-test (EUT) emissions are observed in a particular test technique. In this article, the emissions from two battery-powered laptop computers were investigated using a short wire antenna in the near field.