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Millimeter-wave antenna measurement
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A novel approach is presented to accurately measure the scattering parameters as well as the radiation pattern of planar antennas that operate in the millimeter-wave frequency band. To avoid interconnection problems, RF probes have been used to connect to the antenna. These RF probes are normally used for the characterisation of devices on a semiconductor wafer. Here, they are used to characterise antennas that can be realised in any planar manufacturing technology. A completely planar transition is designed to transform the coplanar waveguide transmission line that is required by the RF probe to a microstrip line. It is shown that this transition can be de-embedded from the measurements. Moreover, a measurement setup has been built for the measurement of the far-field radiation pattern of millimeter-wave antennas and antenna arrays. This setup allows to connect the antenna under test with an RF probe and can measure the radiation pattern in the whole upper hemisphere.
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... For phase-correct measurements with multi-axis robots, position feedback and correction require implementation effort but yield excellent results [5]. Tailored 2-or 3-axis robots using spherical coordinates are, however, less flexible in their applicability, although they offer inherently good measurement performance [15]- [17]. Second, the on-wafer probe has a severe effect on the measured radiation pattern for all frontside radiating antennas. ...
This article presents miniaturized near-field probes to characterize the electric and magnetic fields in the WR03 waveguide band (
$\mathbf \mathrm{GHz}$
to
$\mathbf \mathrm{GHz}$
) on-chip. The near-field probes are based on a commercially available coaxial cable which enables the construction of both open- and short-circuited probes to measure electric and magnetic field components, respectively. Furthermore, it is flexible enough not to damage the wafer under test or the GSG on-wafer probe contacting the chip. It is shown that the measured near fields enable physical insight into the operation of the chip, which also eases fault detection and the search for error sources. Last, the electric and magnetic near fields measured above the chip can be used to calculate the far field of the chip antenna. Here, the usually disturbing influence of the on-wafer probe on the measurement can be significantly reduced if only the near field dominated by the antenna, i.e., in close proximity to the chip, is measured. With this technique, both probe radiation and shadowing can be mitigated. Compared to complex and accurate robot solutions necessary to measure the far field in spherical coordinates, the near-field measurement only requires a cartesian sampling along the chip surface.
... It must be observed that there are a few articles on antenna measurements at millimeter wave frequencies [19], but these articles lack detailed discussion on fabrication and measurement challenges at Ka band. Hence, this article gives a comprehensive converge on the fabrication and measurement challenges for passive millimeter wave antennas. ...
Future cellular communication systems might be based on millimeter wave frequencies. So, there is a need to design and deploy antennas which operate in the millimeter wave spectrum integrated in mobile terminals, portable wireless devices, base stations and access points. Even though a lot of articles exist on the design of such antennas, fabrication and measurement nuances of such antennas are addressed rarely in the open literature. Initially, the fabrication process of printed circuit board (PCB) antennas is discussed in detail with sources of error and possible precautions. A case study of microstrip-based tapered slot antenna operating at 28 GHz is presented. The variations in the antenna characteristics with slight variations due to fabrication errors are presented. A detailed discussion on S-parameters, pattern and gain measurements is also presented along with possible sources of errors associated with them.
... Usually, far-field measurement setups are either set up utilizing metal positioning systems cladded with absorbers [9], [25], or low-loss dielectrics to avoid reflections [19]. Besides the secondary observation of reflections, i.e. observing whether measurement data change when adding absorbers [9], the characterization of the reflections caused by the measurement system has been carried out in a time-domain approach [26]. This section aims to describe a mature method for the selfcharacterization, meaning that the measurement system is used to characterize occurring reflections utilizing the available devices. ...
This paper presents an automatic characterization system for mm-wave antennas based on a spherical positioning system. It features network-analysis based far-field- and S-parameter measurement of probe- and waveguide-fed antennas between 220 GHz and 330 GHz, expandable down to 75 GHz. In either case, the antenna under test (AUT) is fixed in the center of a spherical coordinate system and fed by an appropriate feeding structure, whereas the receiving antenna is moved along the surface of a hemisphere. Since the movement of the receiving antenna is inherently limited to constant radii, the measurement of amplitude and phase far-field-pattern is possible in principle. Additionally to the measurement results of an open-ended waveguide as AUT, this paper describes two methods for the self-characterization of possible systematic and stochastic measurement uncertainties. On one hand, repetitive measurements along a constant trace are carried out to obtain information about the stochastic uncertainty of far-field measurements. On the other hand, a synthetic aperture radar (SAR)-approach is used to characterize possible unwanted reflections within the measurement setup. Finally, the insight obtained from both antenna measurements and self-characterization is concluded into performance parameters of the presented measurement approach.
In recent years, there has been great interest in millimeter-wave (mmwave) and terahertz (THz) technologies due to an increasing demand for ultrahigh data transfer rate. Two novel solutions, i.e., antenna on chip (AoC) and antenna in package (AiP), have been proposed for the development of highly integrated radio and radar systems [1]-[5]. To measure the antenna characteristics of AoC and AiP, a reliable probe-based mm-wave/THz antenna measurement setup became essential. Over the last 20 years, the world has witnessed the prosperous development of various mmwave/THz antenna measurement setups, most of which can be divided into two types, i.e., probe-station and quasi-in-air based. The former type has a feature that allows the testing equipment to be compactly established on a large metal stage, which has been widely used for near-field based and as part of the farfield-based setups [6]-[10]. The antenna under test (AUT) is maintained on a wafer chuck placed on the stage and thus, only the radiation pattern in the upper half-space is measurable due to the metal stage obstruction. The latter type reduces the defect by using an extended supporting structure to hold the AUT in midair away from the stage so that the radiation patterns in both the upper and lower half-spaces are measurable. Many setups of this type measure antennas at far-field distances, and some of them are also compatible with near-field testing. Compared to probe-station based, quasi-inair based takes up much more space and is less compact.
This book discusses antenna designs for handheld devices as well as base stations. The book serves as a reference and a handy guide for graduate students and PhD students involved in the field of millimeter wave antenna design. It also gives insights to designers and practicing engineers who are actively engaged in design of antennas for future 5G devices. It offers an in-depth study, performance analysis and extensive characterization of novel antennas for 5G applications. The reader will learn about basic design methodology and techniques to develop antennas for 5G applications including concepts of path loss compensation, co-design of commercial 4G antennas with millimeter wave 5G antennas and antennas used in phase array and pattern diversity modules. Practical examples included in the book will help readers to build high performance antennas for 5G subsystems/systems using low cost technology.
https://www.routledge.com/Millimeter-Wave-Antennas-for-5G-Mobile-Terminals-and-Base-Stations/Koul-Karthikeya/p/book/9780367445430
Antenna measurements are usually categorized by the location of the measurement facility, either indoor or outdoor. This chapter introduces the antenna parameters that need to be validated in an antenna test facility. The input impedance of the antenna is an important measure that determines how much of the power which is transported along the transmission line is actually radiated by the antenna. Many commercial mmWave antenna test facilities have bulky and metallic moving parts. However, the design of the mmWave anechoic chamber has a confined space where the antenna‐under‐test is positioned such that moving and supporting objects have a negligible effect on the measured radiation characteristics. In over‐the‐air testing, a communication link is setup and some form of information is exchanged between the antenna system under test and the tester, for example by means of transferring data packets in order to determine the bit error rate and the packet error rate.
Design of 5G and beyond 5G telecommunication systems relies on utilization of diverse solutions for different envisioned applications and different constituents of an entire system. One of the research directions is the utilization of a global unlicensed millimeter wave frequency band from 57 to 66 GHz for the high throughput data transfer. Apart from the wide spectrum availability at 60 GHz, there are many problems to be resolved before the concept can become fully functional; one of the requirements is the design of low-cost, energy efficient, wideband antennas with enhanced gain, capable of overcoming propagation losses at 60 GHz. We investigate the benefits and shortcomings of four types of low-cost, printed antennas as the constituents of sub-array elements for the large line-of-sight MIMO arrays. The results are put into perspective by comparison with the most used low-cost microstrip patch sub-array element. The state-of-the-art method-of-moments computations were employed in the highly accurate analyses of the four compared antenna array elements. Although the gains of such sub-arrays can be boosted by the increases in antenna numbers, this does not hold for the efficiency or bandwidth of operation; therefore, radiation patterns and characteristics at the level of individual antennas cannot be ignored as these translate directly into the behavior of an array. Careful choice of antenna type and initial efforts in the sub-array design should be seen as a necessary first step in the design of a large line-of-sight MIMO array of superior characteristics.
Graphic Abstract
Focusing on the design of microwave circuits and components, this valuable reference offers professionals and students an introduction to the fundamental concepts necessary for real world design. The author successfully introduces Maxwell's equations, wave propagation, network analysis, and design principles as applied to modern microwave engineering. A considerable amount of material in this book is related to the design of specific microwave circuits and components, for both practical and motivational value. It also presents the analysis and logic behind these designs so that the reader can see and understand the process of applying the fundamental concepts to arrive at useful results. The derivations are well laid out and the majority of each chapter's formulas are displayed in a nice tabular format every few pages. This Third Edition offers greatly expanded coverage with new material on: Noise; Nonlinear effects; RF MEMs; transistor power amplifiers; FET mixers; oscillator phase noise; transistor oscillators and frequency multiplier.
The design of a novel balanced-fed aperture-coupled patch antenna for millimeter-wave applications is discussed. This completely planar antenna has a balanced feed which electromagnetically couples to a patch through two separate slots. These coupling slots are made resonant in the band of operation to increase the bandwidth and are positioned such that the surface-wave excitation is reduced. A reflector element is placed at the back of the antenna to en- sure a good front-to-back ratio. The antenna can be manufactured in standard printed circuit-board (PCB) technology and can be used in an array con- figuration. The antenna shows good performance in both bandwidth and radiation efficiency. The result- ing design has a bandwidth of more than 10% and a radiation efficiency larger than 80%. Measurements are in good agreement with simulations.
Antenna fundamentals and definitions are examined, taking into account
electromagnetic fundamentals, the solution of Maxwell's equations for
radiation problems, the ideal dipole, the radiation pattern, directivity
and gain, reciprocity and antenna pattern measurements, antenna
impedance and radiation efficiency, antenna polarization, antennas in
communication links and radar, and the receiving properties of antennas.
Some simple radiating systems are considered along with arrays, line
sources, wire antennas, broadband antennas, moment methods, and aperture
antennas. High-frequency methods and aspects of antenna synthesis are
discussed, giving attention to geometrical optics, physical optics,
wedge diffraction theory, the ray-fixed coordinate system, the
cylindrical parabolic antenna, and linear array methods.
The paper presents a novel on-wafer, antenna far field pattern measurement technique for microelectromechanical systems (MEMS) based reconfigurable patch antennas. The measurement technique significantly reduces the time and the cost associated with the characterization of printed antennas, fabricated on a semiconductor wafer or dielectric substrate. To measure the radiation patterns, the RF probe station is modified to accommodate an open-ended rectangular waveguide as the rotating linearly polarized sampling antenna. The open-ended waveguide is attached through a coaxial rotary joint to a Plexiglas(Trademark) arm and is driven along an arc by a stepper motor. Thus, the spinning open-ended waveguide can sample the relative field intensity of the patch as a function of the angle from bore sight. The experimental results include the measured linearly polarized and circularly polarized radiation patterns for MEMS-based frequency reconfigurable rectangular and polarization reconfigurable nearly square patch antennas, respectively.
Vertical single-layer transitions operating at W-band frequencies
have been developed. The designs are uniplanar, use electromagnetic
coupling, and do not require via holes or air bridges. The first
transition uses coplanar-waveguide-mode coupling and results in an
insertion loss of better than 0.6 dB over the whole band, with a loss of
0.25 dB from 85 to 110 GHz. The return loss is better than -10 dB from
75 to 110 GHz. The second transition uses microstrip-mode coupling and
results in a 0.2-dB insertion loss over the whole W-band. These
transitions can prove very useful for millimeter-wave packaging and
vertical interconnects