Antenna Measurement System Research Articles

Compact mmWave measurement system for array antennas in a production environment

Abstract Millimeter wave antenna arrays are essential components of modern communication and radar systems. To produce these devices in large quantities, manufacturers require fast and reliable measurement equipment. The measurement equipment needs to ensure the quality, interoperability, and adherence to regulatory norms of the produced devices. In this work, we present an active probe array structure (PAS), which enables fast, compact, and reliable over-the-air (OTA) measurements of radiation characteristics. No relative movement between the antenna under test (AUT) and the active PAS is required, making the system very suitable for cost-effective large-scale characterization and commercial production test scenarios. We demonstrate and discuss how a near-field (NF) OTA measurement performed by this active PAS system can be used to reconstruct the far-field (FF) antenna radiation behavior of AUTs using an NF to FF correlation approach.

Design of Low-Cost RF Detector for Electric Field Determination in Antenna Radiation Pattern Measurement

Antenna pattern measurement is a requirement for antenna characteristics determination. However, such sophisticated set-up measurement demands skilled authority. This project employed a low-cost RF detector (MAX4003) to capture the E-field and consequently assist in acquiring data for antenna radiation pattern. By fabricating a 3.0V circuit with MAX4003 and connecting to an Arduino, this compact module creates a basic interface between the antenna under test and user’s measurement PC. The results show the measured voltage from the RF detector is in good agreement with the manufacturer’s datasheet for 1.8GHz and 2.1GHz operating frequencies. The input power is also directly proportional to the output power. The project was further tested by conducting a full 360° antenna radiation pattern measurement. The results established a satisfying comparison to theoretical radiation pattern. Overall, the system benefits to individual such as students and researchers to replicate the same method in order to have a compact and attainable antenna measurement system.

Simple photonics-based angle of arrival and Doppler frequency shift measurement system for long baseline antennas.

Using photonics to measure the characteristics of an RF signal has a number of advantages compared to electronics. As a result, many photonics-based RF signal measurement systems have been reported. However, none of them can simultaneously measure an RF signal angle-of-arrival (AOA) and Doppler frequency shift (DFS) while having a simple and low-cost structure that is suitable for use in a long baseline antenna array. This paper presents a microwave photonic system to fill this technology gap. Additionally, the system is designed to have a robust performance, which is needed for practical applications. Measured results demonstrate simultaneous AOA and DFS measurement using the phase difference and the frequency of two low-frequency components generated by the system. The AOA and DFS measurement accuracy are within ±1° over the 0° to 81.5° AOA measurement range and within ±0.05 Hz over the ±50 kHz DFS measurement range. Results also show the system exhibits a stable performance with less than ±0.4° and ±0.02 Hz change in the measured AOA and DFS respectively, over an hour measurement period.

Measurement and performance evaluation of triple band differential integrated extraoral rectifying antenna for data transfer and RF energy harvesting for tongue drive system

Wearable assistive devices are vitally important for tetraplegic individuals to provide valuable insights into their intended directives tailored to tongue motions in wireless healthcare industries. The flexible differentially driven extraoral antenna and rectenna measurement system are developed to enable differential sensing and monitoring of the set of unique tongue gestures for extraoral tongue drive system (eTDS) applications in three frequency bands of Industrial, Scientific, and Medical (ISM) (915.0 MHz, 2400 MHz, and 5800 MHz). The performance analysis is carried out using the heterogeneous human head model. The differential rectifier is coplanarly integrated with the differential extraoral antenna on the same 0.254 mm thin and 9.5 mm wider Rogers RT/ Duroid 6010 LM substrate. The footprint of the fabricated differential rectenna is 0.135 \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\:{\\varvec{\\lambda\\:}}_{\\varvec{g}}\ imes\\:$$\\end{document} 0.082 \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\:{\\varvec{\\lambda\\:}}_{\\varvec{g}}$$\\end{document}\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\:\ imes\\:$$\\end{document} 0.002 \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\:{\\varvec{\\lambda\\:}}_{\\varvec{g}}$$\\end{document} where the planar size of differential rectifier is 15.75\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\:\\:\ imes\\:$$\\end{document} 2.5 mm2. The fabricated systems are situated closely to an artificial head model. The maximum conversion efficiency achieved at 2400 MHz and 5800 MHz is 83.45% and 74.8%, respectively, for 11 dBm of RF input power. Further, the link analysis, including interfacing circuit losses, was carried out theoretically at 915 MHz. Thus, the proposed differential extraoral systems can be employed to acquire and transmit the user intentions in eTDS inspired healthcare applications.

Millimeter-Wave Far-Field Range Antenna Measurement System for a W-Band Monopulse Antenna

In this study, a millimeter-wave far-field range antenna measurement system is proposed for W-band monopulse antenna measurements. Since the W-band monopulse antenna installed in radar systems has many input/output ports, multiple calculations are required to measure all the ports. We propose a system structure capable of the simultaneous measurement of multiple channels to quickly and accurately measure the performance of a monopulse antenna. The proposed measurement system includes a multi-channel rotary joint, a pair of diplexers, and multiple vector network analyzer extenders. In addition, an RF sub-system is implemented to reliably measure the phase of the W-band radiation pattern. It utilizes a shared local oscillator source and external power amplifiers for the transmit and receive paths. Employing the proposed multi-channel antenna measurement system, the sum/difference channels of a monopulse antenna were simultaneously measured according to the azimuth angle. In addition, a comparison of the far-field measurements provided by the proposed system and the near-field measurements was conducted.

Multiprobe Planar Near-field Range Antenna Measurement System with Improved Performance

This article presents a novel multiprobe planar near-field range (PNFR) measurement system. The said system simplifies the overall mechanical design, making it simpler than the existing scanning probe PNFR measurements, and also significantly reduces testing time. A dielectric-based probe is introduced to reduce the antenna size, thereby improving resolution. The probe under consideration is an antipodal Vivaldi antenna offering broadband support and ensuring wideband characteristics of aerials. Numerical results for representative X-band antenna models, presented in the Matlab environment, demonstrate robust performance of the developed measurement system.

Streamlined Millimeter-Wave and Subterahertz Spherical Far-Field Measurement System Supporting Various Antenna Types and Feed Interfaces: Use cases of antenna measurement system

Streamlined Millimeter-Wave and Subterahertz Spherical Far-Field Measurement System Supporting Various Antenna Types and Feed Interfaces: Use cases of antenna measurement system

A performance enhanced P- and L-band double-ridged horn antenna

With the continuous development of electromagnetic detection systems, the working frequency of radar gradually expands towards the low-frequency band such as P- and L-band, and the low-frequency horn antenna has also attracted more and more attention. Given the problems of miniaturization, lightweight and ultra-wideband design of low-frequency horn antenna, this paper presents the optimal design for the feed balun, ridge curve, back-feed cavity and sidewall of the traditional horn antenna, and proposes a performance-enhanced double-ridged horn antenna covering 0.21-2.3 GHz. In the entire working band, the antenna has stable radiation patterns and good port-matching characteristics; its VSWR is less than 2 and the main lobes of patterns do not split or deteriorate. The proposed horn antenna can be used as a standard calibration or measurement antenna in antenna or material measurement systems.

High-Speed Antenna Measurement System Using Multi-Probe Array Technique for 5G Applications

In this article, a high-speed antenna measurement system using multi-probe array technique for 5G application is suggested. The spherical near-field scan measurement system for millimeter wave frequency band (3 GHz–40 GHz) and the multi-probe array rotation method is adopted to improve the antenna measurement speed. The proposed measurement RF system consists of the 14 multi-probe array (28 channel with dual-polarization), switch matrix, downconverters, amplifiers/attenuators, digitizers, and signal generators, and is compared to the conventional planar near-field scan antenna measurement system. The measurement speed performance can be improved significantly and the 3D beam pattern of the AUT can be achieved. The designed system was verified through comparison with a verified far-field measurement system. In addition, to increase the measurement efficiency, an effective sampling technique was proposed and verified.

Untethered near‐field drone‐based antenna measurement system for microwave frequencies using multiple reference antennas for phase and drone location recovery

Untethered near‐field drone‐based antenna measurement system for microwave frequencies using multiple reference antennas for phase and drone location recovery

Rapid MR Scanner Independent B1 Field Measurement System for Phased Arrays.

This paper demonstrates a rapid B1 field benchtop measurement system that is independent of an MR scanner and network analyzer. This system can be used to obtain radiofrequency (B1 field) strength distribution plots of multiple 2D slices (with an extension to 3D) of a liquid cylindrical phantom for multi-element phased arrays used in MRI. The system can be used in three modes- element, phased array, and multiple fixed point pattern measurement. These modes are demonstrated for a 7T 1H eight-channel dipole array and a corn-syrup based phantom. The system can measure complex phase and amplitude measurements from up to 8 elements in the first mode one or 8 different phase settings in the second mode at a rate of approximately 37 positions per minute, allowing a full 2D B1 mapping for 1303 points in 33.05 minutes. The scan patterns obtained using this setup are compared to the ones obtained using an HP network analyzer and simulations. This work can be extended to measure the E field, SAR and upon increasing the speed of measurement, could be used for applications such as Transmit SENSE. Clinical Relevance- This work benefits a faster and more widely accessible measurement system for phased array antennas for MRI. As phased arrays are becoming very important in MRI, the ability to assess individual element performance more rapidly and B1 shimming performance is important to aid in their further development.

Design of Multi-Functional Transmitarray with Active Linear Polarization Conversion and Beam Steering Capabilities

This study designed a multi-functional reconfigurable transmitarray with switchable polarization and beam steering capabilities using only a PIN diode having ON/OFF switching ability. The simulation confirmed that the proposed architecture is capable of 2D beam scanning of up to ±45° for elevation and azimuth while maintaining or converting linear polarization when operating within the X-band. The performance was verified through a far-field beam pattern measurement using the near-field antenna measurement system by producing a transmitarray with an 8 × 8 unit cell arrangement. The maximum level of gain of the proposed architecture was confirmed to be 14.5 dBi, the sidelobe level was below 14.5 dBc, the polarization converting loss was below 1.28 dB, and the polarization isolation level was above 14.7 dB. It can be utilized for the design technique of a radar system demanding small size, weight, power, and cost (SWaP-C) characteristics based on a simplified composition.

Experimental comparison of absorber and conductive floor automotive near field antenna measurement systems

AbstractLarge truncated spherical near-field systems with conductive or absorbing floors are typically used in the measurement of the performances of vehicle-installed antennas. The main advantage of conductive floor systems is the ease of accommodation of the vehicle under test, but their performances are affected by the interaction with the reflecting ground floor. Instead, absorbing-based systems emulating free-space conditions minimize the effect of the interaction with the floor, but generally require longer setup times, especially at lower frequencies (70–400 MHz), where bulky absorbers are typically used to improve reflectivity levels. Considering scaled measurements of a vehicle model, the performances of these two typical implementations are analyzed in the 84–1500 MHz range and compared to free-space measurements. Absorbers with different dimensions and reflectivity have been installed in the scaled measurement setup, and measured data have been investigated with proper post-processing to verify the applicability to realistic systems. Figures of merit of interest for automotive applications, like gain and partial radiated powers, have been compared to free-space to evaluate the impact of different scenarios.

High-order probe compensation algorithm for ultra-wide-band probe in spherical near-field measurement

In order to increase the precision of spherical near-field antenna measurement systems based on wide-band probes, probe compensation algorithms supporting high-order azimuth mode (HOPC) are needed to process the near-field measurement data. In this study, an HOPC algorithm is realized based on the iterative strategy in the reference [ 3 ] for solving the spherical-mode transmission equation with high-order probes. This algorithm is applied to a dual-ridged wide-band horn probe that works in the frequency range of 2–18 GHz. Using dipoles array antennas as examples, the higher precision of the high-order algorithm is illustrated compared with that of the low-order algorithm. The convergence of the algorithm under different conditions is also systematically tested. These results indicate, firstly, the higher-order effects are more remarkable for higher frequency and secondly, when the antenna under test can totally be covered by the 6 dB domain of the main lobe, the iterative process can converge to satisfactory precision within several iterations. Therefore, the algorithm in this paper for HOPC can increase the precision of the spherical near-field system while still preserves high computational efficiency.

A Low-Cost Vertically Integrated Antenna Array at 60 GHz With 85% Efficiency

Although the 60 GHz band meets the higher data rate demands for various wireless applications, large path losses and small size of 5 mm free-space wavelength makes the design, fabrication, packaging, and measurement of 60 GHz antenna arrays challenging. In this letter, we present a low-cost and high-efficiency patch antenna array fabricated using a printed circuit board (PCB) process. As the mini-connector size is larger than unit-cell at 60 GHz, it poses challenges for separate feeding for each array element. This optimized configuration not only addresses the mini-connector assembly shortcoming for off-chip antenna measurements in a laboratory environment but also permits future direct flip-chip integration on a transceiver. Embedded thin-film resistors are first used to fabricate 50 Ω termination and calibration elements on the same board, thus removing associated lossy and bulky external loads and calibration kit. Next, a highly precise robotic antenna measurement system is used to complete the challenging task of measuring far-field pattern at 60 GHz. The proposed 5×5 antenna array is matched at 60 GHz with the -10 dB bandwidth of 3.6 GHz (6%). The peak realized gain of the 5×5 array is 18.5 dBi, and the measured boresight efficiency is 85% at 60 GHz. Furthermore, the simulated maximum scanning volume is ±40° in the E-plane and ±45° in the H-plane. Therefore, the proposed 60 GHz antenna array maintains a low-cost, high-efficiency moderate scanning range with a potential for easy on-chip integration for future communication and sensing applications.

Design of Broadband Double-Ridge Horn Antenna for Millimeter-Wave Applications

In this paper, a broadband double-ridge horn antenna (DRHA) covering 5G millimeter-wave (mm-wave) band is proposed, which maintains stable radiation pattern and gain in the entire band. By redesigning the transition between coaxial and waveguide, there is no splitting or deterioration in the axis pattern throughout the entire 18–54 GHz frequency band, and the VSWRs are all below 2. Meanwhile, by replacing the H-Side wall of the antenna with metal grid, the variation on 3 dB beamwidth of the radiation pattern also become more stable against frequencies. In order to fabricate the prototype successfully, the method of block processing and assembly is adopted, which can ensure high precision machining and make the assembly simple and easy to operate. Prototype measurement results show that the VSWR of the antenna is in well agreement with the simulation ones, while the gain is stable as well as no pattern splitting in the entire frequency band can be observed. It will find potential applications in 5G mm-wave frequency band, especially in the field of antenna measurement system as a standard calibration antenna or a probe antenna.

Robotically‐controlled antenna measurement system for millimeter‐wave applications

AbstractThe characterization of antenna radiation patterns in millimeter‐wave (mmW) bands can be particularly challenging. Due to a small wavelength, minute misplacement of the probe antenna in the order of few millimeters can generate substantial errors in the measured pattern. A highly precise measurement system that incorporates a 6‐axis compact robotic arm is implemented to overcome this challenge. System testing shows a positional accuracy and repeatability of approximately 20 μm or 0.004λ at 60 GHz. After implementation, programming, and testing, the system is used to measure gain patterns on three different mmW antennas. The radiation pattern of a 50–75 GHz standard gain horn antenna demonstrated the accurate measurement at the far‐field using the robotically controlled system. Furthermore, the characterization of the center element pattern of a 60 GHz phased array has shown that the measurements with this system are repeatable and suitable for arrays as well. Additionally, we performed near‐field measurements by successfully characterizing a 40–60 GHz horn antenna with a planar scan.

A Split Ring Resonator-Based Metamaterial for Microwave Impedance Matching with Biological Tissue

A metamaterial lens based on a split ring resonator (SRR) array has been designed and optimized to improve the focusing and the penetration depth in human biological tissue of a microwave beam irradiated by a substrate integrated waveguide (SIW) cavity backed patch antenna. The impedance matching of the antenna loaded with human tissue is strongly improved. The simulations have been performed by using CST Microwave Studio®. A prototype of the device has been fabricated with the printed board circuits (PCB) process and has been characterized using a Network Analyzer and an antenna measurement system in anechoic chamber. A novel microwave applicator for hyperthermia therapy of skin cancer could be developed. The performances of the proposed applicator have been evaluated in terms of measured S11 scattering parameter modulus and simulated power loss density. The obtained results indicate that an SRR-based metamaterial is a promising solution for external microwave applicators to employ in dermatology.

Double U-slot rectangular patch antenna for multiband applications

Multiband applications can be realized as a result of designing a double U-slot rectangular patch antenna. The equivalent circuit of a U-slot patch is presented and the return loss is theoretically derived, utilizing the [A] matrix formulation. CST Microwave Studio software was used to design the microstrip antenna with a transmission line feed and simulate return loss and radiation patterns. The antenna was fabricated in-house using a printed board CNC machine and was measured and compared for return loss using a portable network analyzer. The radiation patterns were measured using a laboratory antenna measurement system. The fabricated antenna was installed on a networked WiFi access point, and tested as far as average received power versus distance range. The antenna is simple, low-cost and easy to fabricate and measurements compared well with simulated results.

Calibration Loop Antenna for Multiple Probe Antenna Measurement System

In order to achieve high accuracy in measurements of the multiple probe antenna measurement system (MPAMS), an omnidirectional calibration antenna with a small gain variation in the horizontal polarization (named calibration loop antenna, in convention) is required. This article presents such an antenna design. The proposed calibration loop antenna consists of four arc-folded dipoles with dimensions of 52 mm $\times52$ mm $\times 1$ mm, balun structures for suppressing common mode current, and four parasitic strips for impedance matching on each of the top and bottom planes. The experimental results show that the proposed calibration loop antenna has a small gain variation in the horizontal polarization less than 0.16 dB in a bandwidth of 20% (2.25–2.75 GHz), and its 10-dB return loss bandwidth is 18.2%. Also, the cross-polarization ratio in the operating bandwidth is greater than 24 dB. Along with the desired omnidirectional radiation pattern, the low profile and compact design further make the proposed calibration loop antenna a suitable selection for calibration in MPAMS.