A hologram-based compact antenna test range (CATR) is being developed to overcome challenges met in antenna testing at submillimeter wavelengths. For the first time, this type of CATR has been built for testing of a large reflector antenna at submillimeter wavelengths. The CATR is based on a 3-m computer-generated hologram as the focusing element. This paper discusses the design and the construction of the CATR, and the verification of the CATR operation with quiet-zone tests done for the CATR prior to the antenna testing. Assembly of the CATR, testing of the 1.5-m reflector antenna at 322 GHz, and the disassembly were all done within two months in 2003. The quiet-zone field measurement results are analyzed in this paper. The CATR was concluded to be qualified for antenna testing. The antenna testing is described in a separate paper.

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Hologram-based compact range for submillimeter-wave antenna testing

5G massive MIMO devices require over-the-air (OTA) calibration and RF measurement in a phase coherent test system. Device and antenna array size make it very challenging to measure RF performance in a true far-field OTA environment due to the large distances required, which also impact the link budget and test system cost. This paper presents a millimeter-wave (mmWave) midfield (MF) OTA RF performance test system designed to minimize size and cost. This system can perform antenna array phase coherence calibration and support RF parametric measurement per 3GPP conformance test specifications. An overview of system design challenges and measurement approaches is provided. Detailed theoretical analysis and simulation of the MF OTA test method are provided, together with experimental validation of the system’s performance to prove its effectiveness in OTA phase coherence calibration and in RF parametric measurement for 5G massive MIMO devices.

Midfield Over-the-Air Test: A New OTA RF Performance Test Method for 5G Massive MIMO Devices

A probe station based setup for on-wafer antenna measurements is presented. The setup allows for measurement of return loss and radiation patterns of an on-wafer antenna-hence-forth referred to as the antenna under test (AUT), radiating at broadside and fed through a coplanar waveguide (CPW). It eliminates the need for wafer dicing and custom-built test fixtures with coaxial connectors or waveguide flanges by contacting the AUT with a coplanar microwave probe. In addition, the AUT is probed exactly where it will be connected to a transceiver IC later on, obviating de-embedding of the measured data. Sources of measurement errors are related to calibration, insufficient dynamic range, misalignment, forward scattering from nearby objects, and vibrations. The performance of the setup is demonstrated from 2 to 40 GHz through measurement of an on-wafer electrically small slot antenna (lambda0/35 times lambda0/35,3.5 times 3.5 mm2) radiating at 2.45 GHz and an aperture coupled microstrip antenna (2.4 times 1.7 mm2) radiating at 38 GHz.

A 2–40 GHz Probe Station Based Setup for On-Wafer Antenna Measurements

In this work, a reflectarray is proposed to be used as a probe of reduced and portable compact-antenna-test range for 5G new radio devices. The reflectarray works at 28 GHz and produces a quiet zone in the near-field region of the antenna. Considering that the quiet zone specifications are established in terms of the amplitude and phase ripple, a synthesis technique is presented to optimize the near field in the Fresnel region of a reflectarray with amplitude and phase constraints. The proposed technique is based on the generalized intersection approach using the Levenberg–Marquardt algorithm as its backward projector obtaining a novel technique in near-field synthesis. This technique is applied to improve the quiet zone radiated by the proposed reflectarray, overcoming the amplitude and phase limitations of the initial configuration. The solution provided by this process is used to design and manufacture a reflectarray based on a three-parallel-dipole cell. Finally, the prototype is measured in a near-field planar range facility in order to evaluate the radiated quiet zone and demonstrate the methodology. The prototype satisfies the tight requirements in amplitude and phase, obtaining promising results.

Demonstration of a Reflectarray With Near-Field Amplitude and Phase Constraints as Compact Antenna Test Range Probe for 5G New Radio Devices

The application of conventional reflector type compact antenna test ranges (CATR), becomes increasingly difficult above 100 GHz. The main problems are the tight surface accuracy requirements for the reflector, and therefore the high manufacturing costs. These problems can be overcome by the use of a new hologram type of compact range, in which a planar hologram structure is used as a collimating element. This new idea is described, and its performance is studied with theoretical analyses and measurements at 110 GHz.

A New Type of Compact Antenna Test Range

Antenna test ranges are required to be capable of measuring the radiation and scattering characteristics of high performance antennas and to operate over a wide range of frequencies. The compact antenna test range (compact range) can fulfil these requirements very well and has established itself as a versatile indoor test range capable of measuring medium to large size antennas over the frequency range of 1 to 300 GHz. The compact range uses one (or more) collimating reflectors to create a region of plane waves, called the quiet zone, in front of a reflector. The paper reviews the principles, history and design of compact ranges. The various types are described and their relative advantages compared. The compact range can be used for both antenna measurements and radar cross-section measurements and shows considerable promise for further development in the future.<
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A.D. Olver

Papers

Compact antenna test ranges