Hybrid OTA Chamber for Multidirectional Testing of Wireless Devices: Plane Wave Spectrum Generator Design and Experimental Demonstration

Abstract

This paper investigates practical implementation aspects of a novel hybrid chamber concept that has been recently introduced for over-the-air testing of wireless devices. The chamber allows to synthesize a spectrum of plane waves (PWs) incident on a device under test from a wide range of anglesof-arrival (AoAs) through exploiting multiple field scattering inside the overmoded waveguide chamber. An optimal design approach for the plane wave spectrum generator (PWSG) array inside the chamber is presented considering: (i) array antenna impedance matching for the desired test zone (TZ) quality and AoAs range; (ii) an operational frequency bandwidth of the test environment and an instantaneous signal bandwidth; and (iii) the impact of the PWSG excitation errors. A robust linearly constrained minimum variance (LCMV) beamformer is formulated to realize the desired test environment over a wide frequency band, while accounting for the varying number of the waveguide propagating modes as excited by the PWSG array. Numerical simulations and measurements with the first prototype of the hybrid chamber for FR1 frequency band (∼3.5 GHz) are presented. This prototype includes a 7 × 7 bowtie antenna element PWSG array, a 1.00 × 1.25 × 1.75 m metal waveguide chamber, an off-line optimal array beamforming setup, and a planar scanner for the TZ characterization.

A Review of Over-the-Air Testing Methods for Performance Measurement of Antennas and Devices in Communication Systems

“…0.0347 CDL-B in [57] 0.0669 CDL-C in [57] 0.0251 International Journal of RF and Microwave Computer-Aided Engineering kind of antenna array which generates uniform plane wave within its near field. A far-field environment can be generated through allocating proper complex weight to each element of the array.…”

“…However, the proposals above ignored the problems occurring in practical implementation including mutual 13 International Journal of RF and Microwave Computer-Aided Engineering coupling effect between antennas, and only performance at single frequency was validated, and the robustness of the optimal solution of excitation was ignored. Regarding the above issues, Iupikov et al proposed a designing method of element in PWG and a prototype of the mixed chamber was achieved and some testing results were shown [57]. This kind of novel fixed chambers represent excellent performance.…”

Characterization and Calibration of the Hybrid OTA Chamber Using a Field Scanner

“…On the other hand, 3GPP standard specifications [15] define the maximum standard uncertainty of the TZ ripples experienced by the DUT as 0.25 dB. Taking into account that it can be described by the Gaussian probability distribution [16], the maximum ripples are 1.28 dB at 99% confidence level. In this paper, we use the σ mag metric to present our results according to the 3GPP specifications.…”

Plane-Wave Generation through General Near-Field In-Band Reflectarray Direct Layout Optimization with Figure of Merit Constraints in mm-Wave Band

“…They consist of array antennas that are optimized to generate a plane wave in their NF region. Although the concept is not new [19,20], it has gained traction in the past few years for over-the-air measurements of 5G devices in the mm-wave ranges [21,22]. The use of conventional arrays generates an issue of requiring complex feeding networks to control the excitation of the array elements [21].…”

“…Although the concept is not new [19,20], it has gained traction in the past few years for over-the-air measurements of 5G devices in the mm-wave ranges [21,22]. The use of conventional arrays generates an issue of requiring complex feeding networks to control the excitation of the array elements [21]. This, in turn, may make the in-band synthesis of these arrays more challenging since the feeding network would, ideally, have to be considered in the simulations to obtain more accurate results [23].…”