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This paper proposes the measurement technique for the phase of 5G NR modulation signal using the fast spherical near-tofar field measurements utilizing the multi-probe combing the multi-receivers. The bandwidth of the 5G NR signal is 100 MHz at 28 GHz with 16-QAM (Quadrature Amplitude Modulation) or 64- QAM TDD (time division duplexing). The reference receiver is utilized since an absolute phase is changed every time. The relative phase at each receiver was recorded, and the medium value was calculated. It can be asserted that the middle value of phase could be similar to the exact value with a little error even for the 5G NR modulated signal.
Extrapolation method is regarded as one of the most accurate methods for obtaining the absolute far-field gain of an antenna. This paper will compare the efficacy of several data processing techniques for calibrating low frequency antennas with long ring down time. Traditionally, measurement data are preprocessed to remove ripples from multipath reflections before a curving fitting is applied. We will first investigate two traditional data processing techniques. The first technique is to apply time domain gating to the vector response vs. frequency data at each separation distance. Then the gated data as a function of distance is fitted to the polynomial equation. The second technique is spectrum domain filtering. The vector response as a function of distance is transformed to k domain at each frequency. A band pass filter is applied in k domain to keep only the direct antenna response. In this study, we propose a new approach - the magnitudes of the antenna response as a function of distance including the ripples is fitted to a more complete generalized antenna response equation with the antenna-to-antenna multiple reflection terms included. This paper will compare the three techniques using a set of measurement data on double-ridged waveguide horn antennas in a fully anechoic extrapolation range.
Compressive Sensing (CS) has been deployed in a variety of fields including wideband spectrum sensing, active user detection and antenna arrays. In massive MIMO arrays, CS has been applied to reduce the number of measurements required to verify the arrays excitation in a production environment. All follow the general approach of creating the sparsity needed for CS by subtracting the measured far-field or near-field of the test array from that of a 'gold standard' array measured under identical conditions. In a previous paper [1] the authors have shown that using a Far-Field Multi-Probe Anechoic Chamber (FF-MPAC) and an optimal sampling strategy CS can offer accurate reconstruction of array excitation with a mean square error (MSE) approaching -40dB using a sampling strategy of just 1.4% of the Nyquist rate. The approach assumed production standard arrays with failure rates up to around 2%. In this paper we extend the concept to using a planar near-field (NF) measurement offering a much more compact test facility that is more suited to the production environment for these antennas. In our initial work the reconstruction of array excitation with a mean square error (MSE) of -30dB was achieved for a 20 x 28 element array antenna at half wavelength spacing using just 1.5% (177 samples) of the samples needed for a conventional NF measurement (12,100 samples) employing back projection to the aperture. Critical to the performance is the realization that the CS samples need to be confined to the central region of the NF measurement plane which for a conventional NF to FF planar antenna pattern measurement would offer a massive truncation error. This paper addresses the optimal sampling strategy needed for this NF approach and presents a statistical performance analysis of the reconstruction accuracy.
The success and efficiency of many classical iterative plane-to-plane based phase retrieval algorithms is to a large extent dependent upon the fidelity of the initializing, i.e. guiding, phase estimation [1], [2]. This is especially so when using these techniques to recover the phase of active electronically scanned array antennas such as those employed within beam-steering mm-wave Massive MIMO antenna systems intended for 5G New Radio applications where the performance of the algorithm, and its ability to not become trapped within one of the (possibly many) local minima, is particularly dependent upon the quality of the initializing guess where access to a phase reference is not always convenient, or even possible. Many traditional phase recovery iterative Fourier methods employ simulation or passive measurement supported phase initialization [1], however this information is not always readily available, or in the measurement may require a destructive, invasive, examination of the device under test (DUT). In this work we address this issue by presenting a proof of concept which employs a machine learning based neural network [3] to estimate the initializing phase function based on the assessment of the measured amplitude only near-field pattern. Here, we show that there is sufficient information contained within the difference between the two near-field amplitude only scans to be able to determine the antenna beam steering characteristics. A simplified beam steering case with electronic scanning in one, or more, scanning axes is demonstrated and verifies the power of the novel method, as well as illustrating its inherent resilience to noise within the amplitude only measurements, and verification of the robustness of the approach thereby extending the range of measurement applications for which this class of iterative Fourier algorithms may be successfully deployed [4].
The BIOMASS Calibration Transponder Antenna (BCT) has been developed to track the BIOMASS satellite and to send calibration signals to it. It has been measured in the ESAESTEC HERTZ facility to ensure its performance before installation. As this anechoic chamber has not been designed to measure antennas at P-Band, its range of applications had to be extended. To this end, spherical nearfield measurements were carried out in order to minimize reflections and decrease measurement uncertainties. Using an average of several measurements, the very high requirements on gain accuracy, crosspolar values, and group delay could be met. However, certain effects in the phase patterns stemming from the chamber that affect the calculation of the phase centre have been observed. This work provides an account on the methods applied to extend the usability of the HERTZ facility, discusses their effectiveness, and infers some generalizations.
Antenna measurements in the VHF band are challenging because of the sensitivity to surroundings in both outdoor and indoor ranges. The large size of the antennas involved makes them difficult to manipulate and therefore more susceptible to damage. In addition, the gain tables for standard gain antennas at these low frequencies is often sparse, especially for older models. This paper proposes to use the three-antenna gain method to mitigate some of these problems by calculating the gains more accurately than other gain calculation methods or the original manufacturer’s datasheets. To this end, a new custom NSI2000 script was written and trialed with a trio of antennas commonly used to test new devices for satellite and space related applications. Using our newly refurbished large anechoic chamber with a nearfield system, gain data calculated in the 200 – 325 MHz frequency range shows notable differences relative to the datasheets. As compared to other methods of gain calculation, the results for the three-antenna method displayed smaller mean values and standard deviations – indicating a reduction in the influence of any single error on the overall outcome. The lessons learned from this experiment can help improve measurement accuracy at these frequencies.
This paper presents a new test procedure to asses and validate key performance indicators for NGSO antennas, and serves to introduce said methodology to the antenna measurement community to foster a discussion on future evaluation procedures for modern day ground segments. Beyond introducing the proposed test methodology we also present results highlighting the actual accuracy of a UAV based measurement system enabling the proposed measurement procedure. The paper is intended to be viewed as an initial proposal for a qualification methodology.
This paper presents a new test procedure to asses and validate key performance indicators for NGSO antennas, and serves to introduce said methodology to the antenna measurement community to foster a discussion on future evaluation procedures for modern day ground segments. Beyond introducing the proposed test methodology we also present results highlighting the actual accuracy of a UAV based measurement system enabling the proposed measurement procedure. The paper is intended to be viewed as an initial proposal for a qualification methodology.
One of the main advantages of a robot-based antenna measurement systems compared to traditional positioning systems like roll-over azimuth positioners are the additional degrees of freedom and, thus, the increased flexibility with respect to the sampling grid and the placement of the antenna under test (AUT). However, this flexibility also requires a precise alignment of probe antenna and AUT to obtain accurate measurement results. In this paper, an electrical alignment technique based on a six term error model is introduced. The misalignment errors are estimated from measurement of single θ-cuts of a reference AUT, using a least-squares optimization approach. The estimation results can be used subsequently to correctly align the probe antenna to the physical position of arbitrary AUTs, independent of the sampling grid. The technique is validated by measurements in the mm-wave frequency range. Results show that the proposed method allows a correction in the same order of magnitude as the repeatability of the robotic system, therefore contributing to an increased overall accuracy of the obtained measurement results.
One of the main advantages of a robot-based antenna measurement systems compared to traditional positioning systems like roll-over azimuth positioners are the additional degrees of freedom and, thus, the increased flexibility with respect to the sampling grid and the placement of the antenna under test (AUT). However, this flexibility also requires a precise alignment of probe antenna and AUT to obtain accurate measurement results. In this paper, an electrical alignment technique based on a six term error model is introduced. The misalignment errors are estimated from measurement of single θ-cuts of a reference AUT, using a least-squares optimization approach. The estimation results can be used subsequently to correctly align the probe antenna to the physical position of arbitrary AUTs, independent of the sampling grid. The technique is validated by measurements in the mm-wave frequency range. Results show that the proposed method allows a correction in the same order of magnitude as the repeatability of the robotic system, therefore contributing to an increased overall accuracy of the obtained measurement results.
In this paper, we propose quantifying the radiated power of phased arrays or, in general, directive antennas, by the Constrained-View Radiated Power (CVRP). The constrained view shall be interpreted here as the Field-of-View (FoV) of an antenna that defines a region in space where focusing the radiated power is highly desired. In the limiting cases, we have that CVRP equals the Total Radiated Power (TRP) when the FoV covers the whole sphere, while, if the FoV reduces to a single point in space, the CVRP equals the Equivalent Isotropic Radiated Power (EIRP). We further present an analysis based on measured radiation patterns of a 16-element, linearly polarized, millimeter- Wave (mmWave), planar phased array antenna operating at 28 GHz. We compare the results to two ideal planar array antennas with the same number of Huygens and cosine elements. The evaluated figure of merit is computed for different scanning angles, as well as for different malfunctions of antenna elements, both for the real and simulated arrays. The results show that the introduced figure of merit could be potentially used for the detection of malfunctioning elements in antenna arrays as well as to characterize the impact of scan loss. Furthermore, CVRP is useful to straightforwardly and significantly characterize the performance of a directive antenna in terms of the power radiated towards a specific region in space.
In a compact range when the antenna is used for both transmitting and receiving in a monostatic fashion, the wave packet senses everything within its view. An extended long object usually gives rise to a bright reflection (glint) when viewed near its surface normal. To take advantage of this phenomenon, a discrete Fourier transform (DFT) on RCS measurements would yield a spectrum of incident wave distribution along that object, provided the scattering property is uniform along its length. Compared with traditional field-probes which translate a sphere across the test zone in horizontal and vertical directions, this new method extends out from the usual quiet zone, and is faster and less interfering to the field being probed. Inspired by this idea, the progression to practical innovation is discussed.
In General, theoretical RF attenuation in free space is characterized according to the Friis equation in far field range The equation says that the free space propagation of electromagnetic waves is inversely proportional to the square of distance from source It holds only in far field range. We investigate a propagation characteristic of millimeter wave in all ranges of field. The study provides measurement results of free space insertion loss from 20GHz to 90GHz of frequency ranges, where the separation between transmitting and receiving antennas is increased from 1mm to 1400mm with 1mm step. The measurement distances cover all range including the reactive and Fresnel ranges as near field, and the far field too. The measuring values are fitted in the free space path loss factor (λ/4πr)2. There are discrepancies between theoretical and measuring values in near field ranges. We added an extra terms to the formula in order to resolve the difference in near field. The results calculated by new formula are shown in good agreement at Fresnel range and also at some parts of the reactive range. The new formula having the extra terms can be also proposed for antenna gain measurements in the near separation between antennas in the context of results according to this study.
Recently, due to rapid technological changes and the global economic system, conformity assessment for products has become international issue. Major countries have established and implemented standardization and management systems for electrical, electronic, and communication devices, including broadcasting and communication equipment, and manufacturers and consumers who use products and parts demand guarantees that they meet international regulations and required global standards. The Korea Radio Research Agency(RRA)'s Communications Conformity Assessment Center(CCAC) has been conducting performance tests on radio wave test antennas owned by domestic test agencies, but since December 2019, the Korea Accreditation Organization (KOLAS) calibration report issued by the domestic antenna calibration agency has been recognized as a performance test report, and indirect management has been carried out by document inspection of the measured value of the antenna for conformity assessment. Accordingly, a proficient test of antenna performance between the CCAC and the antenna accreditation calibration agencies is promoted to get the measurement reliability of the antenna for radio wave test owned by the designated test agency and maintain the same performance test. The test materials for the proficiency test were sequentially tested by four accreditation calibration agencies for three years using several standard antennas mainly used to measure electromagnetic wavelength, resistance and emission characteristics, and field strength characteristics. The En-Score method, an international standard statistical method used to evaluate proficiency test in the calibration field, was applied to the measurement results between the CCAC and antenna accreditation calibration agencies, and it was determined to be meet in all bands of antenna characteristics. Proficiency test promotes the improvement of test capabilities by verifying and correcting the own test capabilities of designated testing agencies through the development and application of test samples. In this paper, we would like to conduct a proficiency test and analyze the identity of the performance test for indirect management of the antenna performance for the conformity assessment.
Recently, due to rapid technological changes and the global economic system, conformity assessment for products has become international issue. Major countries have established and implemented standardization and management systems for electrical, electronic, and communication devices, including broadcasting and communication equipment, and manufacturers and consumers who use products and parts demand guarantees that they meet international regulations and required global standards. The Korea Radio Research Agency(RRA)'s Communications Conformity Assessment Center(CCAC) has been conducting performance tests on radio wave test antennas owned by domestic test agencies, but since December 2019, the Korea Accreditation Organization (KOLAS) calibration report issued by the domestic antenna calibration agency has been recognized as a performance test report, and indirect management has been carried out by document inspection of the measured value of the antenna for conformity assessment. Accordingly, a proficient test of antenna performance between the CCAC and the antenna accreditation calibration agencies is promoted to get the measurement reliability of the antenna for radio wave test owned by the designated test agency and maintain the same performance test. The test materials for the proficiency test were sequentially tested by four accreditation calibration agencies for three years using several standard antennas mainly used to measure electromagnetic wavelength, resistance and emission characteristics, and field strength characteristics. The En-Score method, an international standard statistical method used to evaluate proficiency test in the calibration field, was applied to the measurement results between the CCAC and antenna accreditation calibration agencies, and it was determined to be meet in all bands of antenna characteristics. Proficiency test promotes the improvement of test capabilities by verifying and correcting the own test capabilities of designated testing agencies through the development and application of test samples. In this paper, we would like to conduct a proficiency test and analyze the identity of the performance test for indirect management of the antenna performance for the conformity assessment.
Recently, due to rapid technological changes and the global economic system, conformity assessment for products has become international issue. Major countries have established and implemented standardization and management systems for electrical, electronic, and communication devices, including broadcasting and communication equipment, and manufacturers and consumers who use products and parts demand guarantees that they meet international regulations and required global standards. The Korea Radio Research Agency(RRA)'s Communications Conformity Assessment Center(CCAC) has been conducting performance tests on radio wave test antennas owned by domestic test agencies, but since December 2019, the Korea Accreditation Organization (KOLAS) calibration report issued by the domestic antenna calibration agency has been recognized as a performance test report, and indirect management has been carried out by document inspection of the measured value of the antenna for conformity assessment. Accordingly, a proficient test of antenna performance between the CCAC and the antenna accreditation calibration agencies is promoted to get the measurement reliability of the antenna for radio wave test owned by the designated test agency and maintain the same performance test. The test materials for the proficiency test were sequentially tested by four accreditation calibration agencies for three years using several standard antennas mainly used to measure electromagnetic wavelength, resistance and emission characteristics, and field strength characteristics. The En-Score method, an international standard statistical method used to evaluate proficiency test in the calibration field, was applied to the measurement results between the CCAC and antenna accreditation calibration agencies, and it was determined to be meet in all bands of antenna characteristics. Proficiency test promotes the improvement of test capabilities by verifying and correcting the own test capabilities of designated testing agencies through the development and application of test samples. In this paper, we would like to conduct a proficiency test and analyze the identity of the performance test for indirect management of the antenna performance for the conformity assessment.
As 5G mobile services keep pursuing higher speeds of data transmission based on the use of mm-Waves, they run across problems. The strength of the mm-Wave signal becomes weak very rapidly as the receiver moves away from the transmitter. To overcome the shortcoming, the antenna takes the form of an array of a large size and is fed by amplifiers along the branches of the power divider. It ends up with growth in size and cost. Metamaterials such as transmitarrays have been proposed to increase the antenna gain avoiding the conventional feed circuitry. A metasurface can play a role of the planar lens which is positioned over the primary source. It leads to enhanced antenna gain and reduction in cost and loss. The antenna performances of the metasurface working for 5G and 6G wireless communication are characterized by measuring the radiated field patterns based on the near-to-far field test method and compact range chamber setup (CATR). The measurements present the results of the two methods are in good agreement and the gain improvement.
Measuring the radiation behavior of antennas in an anechoic environment with far-field (FF) conditions requires large measurement sites resulting in high costs. To overcome this problem, near-field (NF) measurement techniques and nearfield to far-field (NFFF) transformation are used to derive the FF of an antenna under test. Thus, evaluating the accuracy and reliability of the NFFF transformation is highly important. The first step for this evaluation process is creating a valid and accurate reference data library consisting of NF and FF data. NF data is used as input to the NFFF transformation, whereas FF data is used as a reference for comparison to the FF obtained after the transformation. This paper explores analytical studies for different antenna models, namely a pyramidal horn antenna and an open-ended waveguide. Simulations of the models are carried out in a commercial full-wave electromagnetic software, considering the various input parameters influencing the FF results. The NF and FF data from the parameterized simulation model is used to evaluate the NFFF transformation methods. After optimization of the simulation parameters, the required accuracy levels of −30 dB and −40 dB for two different accuracy metrics defined throughout the paper are achieved.
Recent advancements in 3D printing technology have enabled the creation of more precise and accurate antennas, allowing for more complex and innovative designs. With the use of new printers and materials, the cost of producing prototype and customized antennas for specific frequency bands has also decreased. Additionally, 3D printing allows for the creation of single-unit devices to replace traditionally multi-part devices. However, challenges still exist, such as the permittivity of printable materials and the surface roughness of the final prints. In this study, standard gain horns and coaxial adapters were printed and coated to explore these challenges. The gain of the resulting horns has been estimated and compared to derive the performance of different printing materials.
In the past few years, the working group (WG) on antenna measurements, being part of the European antenna and propagation association (EurAAP), has spent a great deal of effort in carrying out a whole range of antenna measurement related activities and projects. These activities cover various areas of antenna measurements and are sub-divided into different tasks, such as measurements and comparisons of reference antennas, revisions of IEEE antenna measurement standards, self-assessment measurements of facilities, and emerging techniques for antenna over-the-air (OTA) measurements. This paper gives an update of the status of these activities carried out by the EurAAP WG on antenna measurements including the initial of a new campaign based for a first time on a low directive antenna, an MVG SMC2200 monocone antenna on a circular ground plane. Moreover, the new activities in collaboration with the EurAAP WG on software and modeling tools will be presented with the aim of promoting the benefits of the synergy between measurement and simulation modeling tools.