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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]

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]

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]

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]