Limitations of the Free Space VSWR Measurements for chamber validations

Chen, Zhong; Xiong, Zubiao; Enayati, Amin

doi:10.1109/amtap.2016.7806291

Cited by 9 publications

(5 citation statements)

References 1 publication

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“…Using (2) the computed reflectivity was -13 dB, almost 19dB difference. Using (6) to compute the angle of the reflected ray the new computed reflectivity is -29 dB which is much closer to the measured reflectivity.…”

Section: Revisiting Two Previous Casessupporting

confidence: 66%

“…As the analysis in range 1 showed, since the scanning is only conducted on the horizontal plane, only the reflectivity of the side walls is measured. These limitations of the technique in addition to the ones presented in [6] should be consider in future versions of the IEEE STD 149 [8]. Finally, the comparison has helped in getting a newer equation for the angle of incidence based on the frequency and the electrical thickness of the absorber that provides a more accurate prediction of the QZ reflectivity when compared to the free space VSWR measurements.…”

Section: Discussionmentioning

confidence: 99%

“…Descriptions of this method for evaluating QZ reflectivity levels can be found in [5]. Recently, this methodology has been challenged, since it is being used in cases where it does not apply, and it is dependent on the directivity of the probe antennas [6]. In this paper, four different anechoic range geometries are analyzed using the methods described in [2] and [3].…”

Section: Introductionmentioning

confidence: 99%

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Further refining and validation of RF absorber approximation equations for anechoic chamber predictions

Rodriguez¹

2018

12th European Conference on Antennas and Propagation (EuCAP 2018)

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Indoor antenna ranges must have walls, floor and ceiling treated with RF absorber. The normal incidence performance of the absorber is usually provided by the manufacturers of the materials; however, the bi-static or off angle performance must also be known. In a recent paper [1], a polynomial approximation was introduced that gave a prediction of the reflected energy from pyramidal absorber. In this paper, the approximations are used to predict the quiet zone (QZ) performance of several anechoic chambers. These predictions are compared with measurements performed per the free space VSWR method of four different chambers. Among the chambers analyzed are a 7.3m by 3.65m by 3.65m range with a 24-inch absorber, operating from 1 to 6 GHz with a 91 cm spherical QZ and a 5.18 m path length. Another chamber is 7 m long by 3.3 m wide with a 2.4 m height. 12-inch absorber is used to treat the internal surfaces and the QZ changes from 63 cm to 20 cm from 2 GHz to 18 GHz. The path length is 5.18m. While performing the comparison, changes are made to the calculations to further improve the predictions of the computations. A chamber previously analyzed is computed again after the changes to see whether there are improvements in the prediction. The results show that the polynomial approximations can be used to give a reasonably accurate and safe prediction of the QZ performance of anechoic chambers and improve some of the previous comparisons especially at lower frequencies where the ray tracing is not that accurate.

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Section: Revisiting Two Previous Casessupporting

confidence: 66%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Further refining and validation of RF absorber approximation equations for anechoic chamber predictions

Rodriguez¹

2018

12th European Conference on Antennas and Propagation (EuCAP 2018)

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“…The R level and QZ are two closely related terms in any anechoic chamber. Conventionally, a freespace voltage standing wave ratio (VSWR) method is used for the measurement of R level and QZ [18,25,26,36]. A linear scanning mechanism is generally used to measure the reflectivity.…”

Section: Determination Of Reflectivity Level and Quiet Zonementioning

confidence: 99%

Integration of 0.1 GHZ to 40 GHZ Rf and Microwave Anechoic Chamber and the Intricacies

Suganthi¹,

Patil²,

Chand³

2020

PIER C

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The aim of this paper is to highlight and elaborate the construction and establishment of a rectangular anechoic chamber (AC) of dimensions 7 m × 4 m × 3 m working from 0.1 GHz to 40 GHz. It is an informative checklist giving an insight on the reckoning of chamber dimensions and selection of appropriate absorbers as per the required specifications. It briefs the key features of validation of an anechoic chamber, namely, shielding effectiveness and reflectivity (quiet zone). It describes the intricacies of the integration of systems such as vector network analyzer (VNA), antenna mounting stands, three-axes motorized antenna rotation control circuitry, and customized software. The validation of the established chamber is accomplished for overall shielding effectiveness of −80 dB and reflectivity of −40 dB in one cubic meter area at the receiving antenna or the antenna under test (AUT) region far away from transmitter say, at 5.5 m separation. This paper covers the measurement results of three broadband horn antennas which can be used as reference antennas for characterization of other antennas in the chosen frequency range. The entire report will certainly be a guideline for any reader or aspirant who is interested in the development of a similar anechoic chamber and looking for complete intricacies.

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“…Traditionally, the Free-Space Voltage Standing Wave Ratio (FSVSWR) test is conducted to measure the anechoic chamber reflectivity measurements as mentioned in the IEEE149-1979 standard [123]. Although the FSVSWR test yields the chamber reflectivity, there are limitations to the technique, and the results vary based on the probe antenna used [124]. In addition to the FSVSWR test, another technique for chamber characterization is based on Fourier analysis [121,120] that has since been adopted in the next revision of the IEEE 149 standard.…”

Section: Introductionmentioning

confidence: 99%

Multiple UAVs for synchronous-shared tasks and longterm autonomy

Diddi¹

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Limitations of the Free Space VSWR Measurements for chamber validations

Cited by 9 publications

References 1 publication

Further refining and validation of RF absorber approximation equations for anechoic chamber predictions

Further refining and validation of RF absorber approximation equations for anechoic chamber predictions

Integration of 0.1 GHZ to 40 GHZ Rf and Microwave Anechoic Chamber and the Intricacies

Multiple UAVs for synchronous-shared tasks and longterm autonomy

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