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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]

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]

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]

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]

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]

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 comparison between different modern heuristic optimization methods applied to antenna far-field radiation pattern reconstruction from planar near-field data is presented in this paper. The antenna under test is represented by means of equivalent magnetic currents (EMC) whose components are optimized using several heuristic algorithms such as simulated annealing (SA), genetic algorithms (GA), and particle swarm optimization (PSO), as well as a traditional local optimization method, the Nelder Mead downhill simplex algorithm. Several schemes for GA (classical real-valued and binary encoding, and their hybrid versions) and PSO (global or local topologies with synchronous or asynchronous updates of the swarm) have been considered in the analysis and the pros and cons of each one are reported and discussed. A study of the performance and limitations of each algorithm using as a canonical problem a small size antenna aperture, along with results of near-field to far-field (NF-FF) transformation are also included [ABSTRACT FROM PUBLISHER]

By supporting an L-probe coupled circular patch antenna with four metallic posts at appropriate locations, it is demonstrated that the conical and the broadside modes which are excited separately by two different sets of L-shaped probes, can be operated at the same frequency range. For a tested antenna operated at 1.85 GHz, the bandwidth (SWR<2) achieved is 24%, and the isolation between the two input ports is 28 dB. The gains of the conical and broadside modes are 4 and 8.5 dBi, respectively. With suitable switching feed networks, the antenna can be reconfigurable in radiation pattern. The antenna can also be used as a pattern diversity antenna for modern mobile communications. [ABSTRACT FROM PUBLISHER]

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]

Testing of satellite antennas at high millimeter and submillimeter wavelengths has some specific problems not encountered at lower frequencies. The atmospheric attenuation due to water and oxygen molecule resonances at certain frequency bands can be substantial. Therefore, conventional far-field test methods for electrically large antennas are ruled out by the required far-field distance of kilometers or even tens of kilometers. However, the compact antenna test range (CATR) makes such far-field tests possible within an indoor chamber having a controlled atmosphere. The application and ongoing development of a CATR based on a hologram as the focusing element are outlined [ABSTRACT FROM PUBLISHER]

In this work, the influence of resistive absorbers in the vicinity of small antennas was investigated, in order to define a lower limit for the size of a small anechoic chamber for antenna calibration and radiation pattern measurements, with respect to the distance between the antenna under test (AUT) and the RF absorbers lining the walls. Furthermore, the influence of a relatively narrow transmission channel, formed by the absorbers on the side walls between the measurement antenna and the AUT was investigated. It was found by measurements that absorbers with the length of 610 mm do not have a measurable effect on the radiation characteristics of a small antenna at around 1.8 GHz, as long as they are kept more than 100 mm from the AUT, and the transmission channel formed by the absorbers between the antennas is wider than 100 mm [ABSTRACT FROM PUBLISHER]

The photoconductive terahertz measurement technique was used for measurement of the radiation pattern from thick metal slits. Picosecond pulses were generated and detected by an ultrafast optoelectronic technique using a femtosecond pulse laser and a subpicosecond photoconductor. Photoconductive sampling measurements of the polarization-dependent diffraction of the picosecond electromagnetic pulses showed the highly polarized radiation characteristics of the photoconductive probing antenna (PCPA) compared with the finite-difference time-domain simulation. The radiation patterns from the slits were measured using a fiber-coupled PCPA. Investigation of the spatiotemporal radiation pattern from a thick metal slit shows the usefulness of the measurement set-up for time-domain and broadband antenna characterization. Together with the time-domain radiation pattern, the frequency-domain radiation pattern from the experimental transient response is presented in both amplitude and phase. It is demonstrated that the time-domain radiation pattern measurement using the photoconductive terahertz radiation technique is a promising characterization method for millimeter-wave and submillimeter-wave antenna time-domain testing [ABSTRACT FROM PUBLISHER]

If modern airborne radar systems are to function properly, the radar antenna radiation patterns must meet certain specifications. Until recently, most radar antennas were designed and tested in a clean antenna environment, i.e., there is no near field scattering from host structures or radome effects. However, these higher order effects are the matter of increasing concern with added performance demands in the ever-increasing jammer and clutter interference environments. We investigated the capabilities and limitations of currently available analysis techniques and computer codes for installed performance of airborne radar antenna systems. Then we developed an extended ray-optical technique that could predict total installed performance of airborne radar antenna systems, i.e., the near field scattering from aircraft structures and radome effects. The new analysis technique utilized a ray-tracing method in both airframe and radome simulation. Thus, it can efficiently predict the total installed performance of large radar antenna systems on an aircraft structure [ABSTRACT FROM PUBLISHER]

Indirect holography provides a quick and inexpensive three-dimensional (3-D) imaging technique at optical frequencies which has not been directly adapted to microwave imaging. This letter describes a technique whereby a radiated offset reference plane wave can be electronically synthesized allowing this technique to be used at microwave frequencies. In this letter, this technique has been applied to the problem of determining antenna radiation patterns and reconstructing complex near fields. Early experimental results compare favorably with results taken using traditional methods. [ABSTRACT FROM PUBLISHER]