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Antenna chambers are RF‐shielded enclosures which are required for antenna and radio performance measurements. Typically, anechoic chambers (ACs) are used for measuring directional metrics (e.g. antenna pattern, effective isotropic power etc.), while reverberation chambers (RCs) are widely used for non‐directional measurements (e.g. antenna efficiency, total radiated power etc.). When a device under test requires both types of measurements, testing needs to be conducted sequentially in an AC and an RC. This leads to significant time inefficiencies due to the need to set up and calibrate two separate measurement setups in two different chambers. To address these issues, this letter proposes a programmable chamber framework capable of electronically switching between AC and RC modes by programming the reflective intelligent surface‐enabled sidewalls. This framework is highly attractive for the industry as it supports both directional and non‐directional measurements within a single chamber. The letter outlines the conceptual framework, discusses design considerations, and presents preliminary experimental validation of reflective intelligent surface‐enabled sidewall with the designed phase‐setting configurations to emulate the radio absorber sidewall of an AC and the metal plate sidewall of an RC. The experimental results demonstrate the effectiveness and potential of the proposed approach. [ABSTRACT FROM AUTHOR]

Automotive antennas are gaining importance due to their increasingly important role for autonomous driving with the development of the Internet of Vehicles. However, over‐the‐air testing on automotive antennas is difficult owing to its large volume and complex body structure. Plane wave generators can approximate uniform plane waves in the near field of the device under test, which can greatly reduce the measurement distance and thereby decreasing the cost compared with direct far‐field solutions. This letter designs three plane wave generators for three quiet zone sizes selected according to the vehicle structure at 5.9 GHz, achieving quiet zone sizes of 1.45 m ×0.23$\times 0.23$ m, 2.9m ×0.56$\times 0.56$ m, and 3.9 m ×1.27$\times 1.27$ m, respectively. Within the three quiet zones, amplitude deviations of 0.82, 0.34, and 0.34 dB and phase deviations of 9.4∘${9.4^\circ }$, 6.72∘${6.72^\circ }$ and 1.42∘${1.42^\circ }$ are realized, respectively, according to the numerical simulations. Uncertainty analysis is further implemented to investigate the robustness of the designed PWGs proposed in this letter. [ABSTRACT FROM AUTHOR]

The integration of directive elements into a circular switched parasitic array at 868 MHz is presented. The typical usage of reflective parasitic monopoles is supplemented with additional, shorter monopole elements which are positioned closer to the central active monopole to induce directive behaviour. This allows for more degrees of freedom with the steering of the antennas beam and to increase the gain of the antenna. This leads to a greater flexibility of the system and enables power reduction of the amplifiers for enhanced battery life time. The design and configuration of a circular switched parasitic array with directive elements is shown and a prototype is built for validation. [ABSTRACT FROM AUTHOR]

Ever‐increasing bandwidth requirements from various industries drive the need for the ever‐increasing bandwidth of antennas used for testing. Broadband Double‐Ridged Guide Horn (DRGH) antennas are used extensively in antenna measurement and ElectroMagnetic Compatibility/Interference (EMC/I) testing. The current state‐of‐the‐art broadband DRGH antennas reported in the literature for use in measurement applications cover bandwidth ratios as large as 36:1 (0.5–18 GHz). This paper presents the design and realisation of a DRGH antenna with a 100:1 bandwidth ratio (0.5–50 GHz). To achieve such a wide bandwidth, the ridge gap, width and feed were optimised, and a novel coaxial‐to‐ridge waveguide launcher section based on a typical Vivaldi antenna was developed. Backward radiation was reduced using an absorber‐filled cavity. A prototype DRGH antenna was manufactured using additive manufacturing, also referred to as 3D printing. Simulated and measured results obtained in an anechoic chamber are presented. [ABSTRACT FROM AUTHOR]

Traditional microstrip antennas have problems with heavy weight and poor gain. In order to reduce the weight of the antenna itself and improve its gain, the preforms of the 3-D woven rectangular hollow structure conformal bearing microstrip antenna (3DWRHS-CB-MA)with different heights were woven from ultra-high molecular weight polyethylene (UHMWPE) filament yarns and copper wires on a common loom through reasonable design. The preform was used as the reinforcement and epoxy resin was used as the matrix, four different heights (2, 4, 6, and 8mm) of 3DWRHS-CB-MA were prepared by vacuum-assisted resin transfer molding (VARTM) process. Finally, the electromagnetic performance was analyzed by high-frequency structure simulator (HFSS) and experimental testing. The results showed that the frequency deviation of the 2 mm height microstrip antenna was minimal; while the 4 mm height microstrip antenna had better gain efficiency and directional diagram compared to others. The 4 mm height microstrip antenna has good radiation performance with a weight of only 35 g which shows that 3DWRHS-CB-MA are potential candidates for future intelligent textile materials and wireless communication fields. Highlights • Weaving with UHMWPE filament yarns and copper wires on common looms. • The preform was used as the reinforcement, and epoxy resin was used as the matrix. • Simulation of electromagnetic characteristics of antennas using HFSS software. • Proving the effectiveness of the electromagnetic simulation model. • Revealing the electromagnetic radiation mechanisms. [ABSTRACT FROM AUTHOR]

Since the total number of the antenna elements can be up to hundreds in a massive multiple‐input multiple‐output (MIMO) system, subarray‐structured base station (BS) array configurations are widely adopted to achieve a good cell coverage and to reduce the required number of radio frequency chains at the same time. It is crucial for any BS product to ensure that the antenna elements perform correctly as expected. Therefore, the necessity of array diagnosis is evident, especially for large BS arrays. Furthermore, it is essential that the diagnosis can be achieved in a compact and cost‐effective setup with high measurement efficiency (i.e. only a few measurement samples are required). The principle of the diagnosis method presented in this article is to obtain the S‐parameters between the subarrays and the probe via solving linear equations. In the simulation, a BS array composed of 16 subarrays with each containing 3 elements is used to validate the diagnosis method at 3.5 GHz. An array composed of 4 subarrays with each containing 3 elements was used in the measurements to verify the diagnosis method with two different phase tuning matrices at 3 GHz. Successful diagnosis results have been achieved in both the simulations and the measurements. [ABSTRACT FROM AUTHOR]

This letter presents a comprehensive analysis of the radiation behaviour exhibited by nine distinct on‐wafer radio‐freqeuncy (RF) probes used for device characterization in the mm‐wave bands of integrated circuits and antennas. The tested probes are sourced from two different manufacturers and feature various probe pitches. All probes are intended for use with the WR‐3.4 waveguide band ranging from 220 to 330 GHz. To the best of the authors' knowledge, such a detailed examination of RF probes operating in this band with respect to their radiation behaviour has not been demonstrated before. [ABSTRACT FROM AUTHOR]

An effective, probe‐compensated, phaseless Near‐Field‐Far‐Field (NF–FF) transformation technique with planar spiral scanning is presented. The phase retrieval problem is solved by a quadratic inverse process, whose data are the voltage squared amplitudes of the NF samples acquired on two scanning surfaces. The available information on the antenna under test and on the scanning geometry are used to provide efficient representations for both the unknowns and the data, thus improving the accuracy and reliability of the technique. Furthermore, disconnected apertures are dealt with by adopting two different sets of prolate spheroidal wave functions to represent the aperture fields. Experimental results are reported to assess the effectiveness of the proposed approach. A drastic reduction (about 90%) of the required NF samples, as compared to standard λ/4 measurements (λ being the wavelength), is observed. Aggregating the measurements on the two scanning surfaces, the technique uses less samples even when compared to the case of complex, λ/2 measurements performed on a single surface. Our approach exhibits an accuracy comparable to that achieved when adopting complex measurements with non‐redundant sampling or classical, λ/2 plane‐rectangular NF–FF transformations. [ABSTRACT FROM AUTHOR]

Canonical objects with known radar cross section (RCS), for example, the trihedral corner reflector (TCR), play a crucial role in the calibration of automotive radar sensors. Moreover, these canonical objects are also used in the validation of simulated RCS obtained using asymptotic methods, such as hybrid geometric optics (GO) and the physical optics (PO) based methods. However, accurate RCS prediction with asymptotic methods is highly dependent on the individual scattering mechanisms considered in a simulation, for example reflection and diffraction from the TCR surfaces and edges, respectively. Reliable measurements are therefore required to evaluate if a particular interaction mechanism can be neglected to reduce computation complexity without adversely affecting the accuracy of the predicted RCS. In this letter, the monostatic scattering characteristics of three metallic TCRs are investigated with varying geometrical sizes in the E‐band, that is, from 60 GHz to 90 GHz. The ultra‐wideband (UWB) measurements, which offer a high delay resolution, can enable the identification of the individual scattering mechanisms. Diffraction from the TCR edges is experimentally demonstrated to contribute to a non‐negligible scattered power in this frequency band. [ABSTRACT FROM AUTHOR]

In millimetre wave (mmWave) frequency band, radio resource management (RRM) performance is characterised in plane wave conditions using radiated over‐the‐air test method, which is a challenging combination of protocol and radio frequency performance measurement. This article presents a novel design of multiple lens‐based compact antenna test ranges (CATRs) to simulate multiple angles of arrival from different base‐stations in RRM measurement. Only four lens‐based CATRs are proposed to create plane wave conditions at the device under test with six different angles of arrival and capable of accurately constructing the wireless propagation condition and minimising the diffraction and scattering between adjacent CATRs. The lens‐based CATR is the key element in the RRM measurement system, which is composed of a metasurface lens for phase alignment and a 2 × 2 feed array antenna for the emission of electromagnetic signals. The function and capability of the proposed lens‐based CATR is validated through simulation and measurement, that the worst‐case amplitude variation in the quiet zone region is lower than ±0.8 dB at 26 GHz, and phase variation is lower than ±7.5° in the designed quiet zone, which could be used in the fifth‐generation mmWave RRM measurement. [ABSTRACT FROM AUTHOR]

The theoretical foundations of the near to far field transformation (NTFFT) techniques with spiral scannings have been properly applied to develop a non‐redundant spherical spiral NTFFT which properly accounts for a mounting of a volumetric antenna under test (AUT) in an offset configuration, due to any practical constraints. Such an NTFFT, based on the non‐redundant sampling representations of electromagnetic fields using spherical modelling of the AUT, requires the same number of near‐field (NF) spiral data when the AUT is mounted both in onset and offset configuration because this number depends only on the area of the modelling sphere centred at the AUT centre. Moreover, it employs an efficient two‐dimensional (2D) optimal sampling interpolation (OSI) formula to recover, from the spiral NF samples, the massive number of NF data required by the classical spherical NTFFT, which is related to the radius of the smallest sphere enclosing the AUT and centred at the scanning sphere centre. It is so possible to get a remarkable measurement time saving when the AUT is offset mounted. Numerical and experimental results, fully assessing the effectiveness of the developed NTFFT and the related 2D OSI algorithm, are shown. [ABSTRACT FROM AUTHOR]

This investigation primarily promotes a ultra-high frequency radiofrequency identification (RFID) tag antenna for complex environment applications of smart card in free space and near body scenarios. It also considers other high dielectric materials such as water and metallic objects. A dual dipole antenna with T-match structure is chosen due to the advantage of providing high resilience towards change in impedance of high dielectrics, and to ensure the reception of maximum signals at the blind spots of the antenna. The proposed geometry facilitates placement of other off-the-shelf high and low-frequency antennas on the card, enabling more features, higher performance, and minimum field interaction between different frequencies. A presented RLC equivalent circuit model estimates the impact of body layers on antenna impedance. A high read range of 7.7 m in free space, 5.2 m near body and 2.8 m at the blind spots is obtained. The novelty is shown by testing the antenna near metals and water, achieving high read range without any design modifications. The proposed tag aims to provide new RFID applications that demand small size, less volume, low cost and multifunctionality over various constraints while showing good agreement with sensitivity, impedance matching and the read range. [ABSTRACT FROM AUTHOR]

The classic method of testing array antenna is measuring the beam pattern separately, which suffers from low efficiency. In this study, a fast measurement method used for received array antenna has been present. Firstly, the patterns of element antennas have been tested using multi-channel receiver. Then the entire pattern could be computed by weighting the information of elements. The information contains amplitude and phase, which could be obtained by theory or measurement. [ABSTRACT FROM AUTHOR]

The authors present a test method for quantifying and reducing systematic errors arising from antenna proximity to lossy objects in over‐the‐air performance testing of lossy large‐form‐factor wireless devices. The method determines the extent to which antenna proximity to lossy, large‐form‐factor objects influences the measured reference power transfer function. The test may be used to pre‐characterise a given chamber set‐up in terms of a minimum distance between antennas and lossy objects. They illustrate the use of the method in a total radiated power measurement of a large, commercially available, machine‐to‐machine device, where agreement to anechoic‐chamber measurements is demonstrated to within the measurement uncertainty. [ABSTRACT FROM AUTHOR]

Measurements in reverberation chamber (RC) produce data that are random, and therefore they need to be processed from the statistical point‐of‐view for obtaining the desired characteristics and the accuracy. The complex channel transfer function in the RC follows complex Gaussian distribution provided that the RC is well stirred. The authors have recently presented a new uncertainty model based on the presence of an unstirred component of the transfer function, which was modelled by introducing an average Rician K‐factor. The model was validated in two RCs with translating mode‐stirring plates, being able to correctly describe the improvement in accuracy by rotating the antenna under test, and by blocking the line‐of‐sight between this and the fixed RC antenna(s). In the present study, they apply this uncertainty model to four RCs with different settings (e.g. RC volumes, number of plates or fixed RC antennas, translating and rotating mode‐stirrers etc.). For each RC, they examine the measurement uncertainty under different loading conditions. To repeat (during the different measurements) the actual mode‐stirrer positions at which the transfer function is sampled, they conduct all the measurements with stepwise (instead of continuous) mode‐stirring. The model is shown to work well for all the cases. [ABSTRACT FROM AUTHOR]

In this Letter, a tri‐reflector compact antenna test range (CATR) with a paraboloidal main reflector and two shaped sub‐reflectors is synthesised by the kinematic and dynamic ray tracing method, while the high cross‐polarisation isolation is achieved through the proposed system geometry. Numerical simulations by general responsibility assignment software patterns demonstrate that a cross‐polarisation isolation >40 dB and a peak‐to‐peak amplitude (phase) ripple <1 dB (10°) can be achieved on the principal cuts of the designed quiet zone at 90–325 GHz. This clearly shows that the high cross‐polarisation isolation in such a tri‐reflector CATR can be achieved by the proposed antenna geometry without depolarisation control in the shaping procedure. [ABSTRACT FROM AUTHOR]

A planar super‐wideband (SWB) antenna fed by an asymmetric coplanar strip is proposed, fabricated, and tested. The antenna consists of a hexagonal loop strip in which a signal strip is prolonged, curved, and shorted to a ground plane to facilitate SWB characteristics. In addition, by adding a boomerang‐shaped strip to the ground plane, the effective electrical length is increased, thereby decreasing the lowest operating frequency. The simulated results show that the proposed antenna exhibits a −10 dB reflection bandwidth from 1.18 to 49.22 GHz corresponding to a ratio bandwidth of 41.7:1. The measured results of the fabricated antenna are also represented and compared with the simulated results. The antenna gain changes from 2.05 to 10.62 dBi within the measured frequency range. [ABSTRACT FROM AUTHOR]

A non-perturbing, fast, low-cost probe for near-field measurements is presented in this paper. The new sensing technique's capabilities in antenna fault diagnosis and direct measurement of field intensity distribution at subwavelength distance from the sources are demonstrated by test measurement on different microwave antennas and applicators. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 95–98, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10981 [ABSTRACT FROM AUTHOR]

A quick review of the planar phaseless near‐field antenna measurement technique is presented and some interesting aspects related to the size of the mask used at the aperture of the antenna under test (AUT) are pointed out. It is shown simulatively and experimentally that due to the edge fields the AUT aperture's mask needs to be larger than the physical aperture of the AUT to achieve better accuracy. In addition, the misalignment of the setup has a big impact on the achieved far‐field accuracy. This is emphasised experimentally. [ABSTRACT FROM AUTHOR]

A novel and simple approach to adjust the polarisation properties of a microstrip patch antenna in the entire axial ratio (AR) range is proposed. The proposed antenna consists of a radiating patch and a parasitic strip separated into two parts, and the separated strip is placed at the outer perimeter of the patch for capacitive coupling. This structure enables the antenna to induce opposite‐direction currents on the strip, which allows flexible polarisation adjustment by moving the separated positions of the strip. For evaluation, two antennas with linear and circular polarisations are fabricated, and their performance is measured in a full anechoic chamber. The results prove that the proposed approach is suitable for flexible AR adjustment without a significant degradation of the matching characteristics and the design complexity. [ABSTRACT FROM AUTHOR]

A beam‐deflection short backfire antenna (BD‐SBA) is proposed. The BD‐SBA consists of an SBA and a deflection plate. The deflection plate is designed to change the phase of the reflected waves, hence deflecting the beam of the BD‐SBA. The beam deflection can realise different beam pointing within about 20°. An X‐band antenna (10 GHz) with a beam pointing of 12° is fabricated and tested. The measured results demonstrate that the desired beam deflection is obtained. A gain of 14.3 dBi and a sidelobe level of −20.6 dB are realised. The BD‐SBA, with a simple structure, low cost and moderately high gain, is suitable for the application of fifth‐generation wireless backhauling potentially. [ABSTRACT FROM AUTHOR]