Passive Antenna Research Articles

Redirection and Splitting of Sound Waves by a Periodic Chain of Thin Perforated Cylindrical Shells

The manipulation of $l\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}g\phantom{\rule{0}{0ex}}h\phantom{\rule{0}{0ex}}t$ via engineered structures (metamaterials) continues to inform the manipulation of $s\phantom{\rule{0}{0ex}}o\phantom{\rule{0}{0ex}}u\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}d$. The authors show analytically that a periodic chain of perforated metallic shells can transform an audible sound of wide frequency spectrum into two monochromatic waves that propagate along the chain in opposite directions. Such a chain may serve not only as a splitter and redirector of acoustic waves, but also as a passive antenna that points the way back to the source of the incoming sound.

Design of penta-band low noise amplifier with integrated active antenna for vehicular communications

The design and integration of penta-band planar antenna with a low noise amplifier (LNA) for vehicular wireless applications is discussed in this research. By integrating antenna with a LNA, the return loss can be kept low with the increased bandwidth compared with a passive antenna with the same design. The performance of the passive antenna, LNA, and integrated active antenna (IAA) are individually validated with the aid of vector network analyzer. The designed IAA covers navigational frequencies 1.2 and 1.5 GHz, wireless communication frequencies 2.4, 3.3 GHz and dedicated short range communication frequency 5.8 GHz, with LNA gain (>10 dB) and noise figure (<2 dB). The proposed design gives room for simultaneous reception of all the desired frequency bands with better performance for vehicular communications.

Optical electric field sensor sensitivity direction rerouting and enhancement using a passive integrated dipole antenna

This work introduces a passive dipole antenna integrated into the packaging of a slab-coupled optical sensor to enhance the directional sensitivity of electro-optic electric field measurements parallel to the fiber axis. Using the passive integrated dipole antenna described in this work, a sensor that can typically only sense fields transverse to the fiber direction is able to sense a 1.25 kV/m field along the fiber direction with a gain of 17.5. This is verified through simulation and experiment.

Patch antenna sensor rosettes for surface strain measurement

Passive (battery-free) wireless patch antenna sensors have been developed in recent years for strain sensing, to provide convenient and low-cost instrumentation. Despite past efforts, current analytical and experimental studies have mainly focused on performance in single-axial measurement, which is simple and unrealistic from typically encountered arbitrary plane stress fields. This paper presents strain sensor rosettes made of folded patch antennas and slotted patch antennas for measuring an arbitrary surface strain (plane stress) field. The transverse strain effect of both sensors is discussed and has been validated through laboratory experiments. Multiphysics coupled simulation is conducted to describe accurately the mechanical and electromagnetic behaviours of antenna sensors. Resonance frequency shifts of the antenna sensors are used to derive the three strain components in an arbitrary plane stress scenario – that is, two normal and one shear strain components. Both numerical studies and experimental validations have been performed.

An Improved Method for Efficiency Measurement of All-Excited Antenna Array in Reverberation Chamber Using Power Divider

Reverberation chambers (RCs) are ideally suitable for antenna efficiency measurements. For the measurement of the efficiency of a passive all-excited antenna array in an RC, a power divider is normally used to excite all the ports of the array simultaneously. The presence of the power divider introduces additional insertion loss to the antenna array. How to calibrate the insertion loss accurately is a problem for such a measurement. In the existing method, the effect of the mismatch between the array elements and the power divider was not taken into consideration, which could result in inaccurate evaluation of the efficiency of the antenna array. In this paper, an improved method of measuring the antenna array efficiency is presented. It allows the de-embedding of the power divider which removes the insertion loss of the power divider, thus it obtains the efficiency of an antenna array more accurately. This is realized by introducing proper attenuators between antenna array elements and power divider ports. Simulations and measurements have been conducted to verify the proposed method. It is shown that this method is accurate even when the array elements are not well matched with the power divider, especially for the wideband antenna arrays, where good impedance matching of array elements is difficult to maintain. The advantages and limitations of this approach are also discussed. The proposed method should be very useful for accurate and efficient measurement of antenna array efficiency.

Design of mid-plane passive active multijunction antenna for 5-GHz KSTAR LHCD system

The major upgrade of KSTAR LHCD system to 4MW is planned in 2021. 4-MW RF power will be provided by 8×0.5MW klystrons. Highly oversized circular waveguide transmitting TE01° mode will be adopted for the low loss transmission line longer than 50m. The design of the 4-MW mid-plane Passive Active Multijunction launcher has been performed. Considering parallel refractive index N|| for the efficient current drive and the maximum power density at the launcher mouth, the launcher is composed of 256 active waveguides whose dimension is 58mm x 7mm and 18mm of spatial period for N||0=2.5. Multijunction with Emax <3.5kV/cm and high power waveguide components have been designed using HFSS code. The antenna properties were evaluated using ALOHA. Prototype PAM launcher with 32 active waveguides is under development for 0.5-MW pulsed operation.

Interventionless Reservoir-Isolation Valve Removes Need for Intermediate Completion

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 184706, “Interventionless Reservoir-Isolation Valve Removes the Requirement for an Intermediate Completion: A Case Study,” by Andrew Edwards, SPE, Euan Murdoch, SPE, and Christopher Munro, SPE, Weatherford, prepared for the 2017 SPE/IADC Drilling Conference and Exhibition, The Hague, 14–16 March. The paper has not been peer reviewed. This paper focuses on the application of radio-frequency-identification (RFID) technology to enable an operator to eliminate an intervention run (or intermediate liner) for a 10,000-ft reservoir section. The case-study well has preperforated liner in two zones isolated with swellable packers and pressure-actuated annulus packers. The typical procedure is to straddle the annulus packers individually using an inflatable plug, but setting the lower annulus packer incurs additional risk while running in the horizontal for an extended distance. Here, an RFID-actuated reservoir-isolation valve (RIV) eliminates an intervention run. Methodology RFID is now a common technology used across various industries to provide a means of communication between a passive antenna and an active antenna. This technology has now been adapted and applied to actuate downhole tools in oil and gas wells. In the RFID portfolio, the installed equipment houses the active antenna and RFID tags that are deployed at surface and provide the passive antenna. The tool provides a secure, pressure-resistant encasement for the electronics required. The RFID tag contains a memory bank to store a command that is programmed at surface and a coil that takes power from the radio-frequency field generated by the active tool antenna. This power provided by the active antenna is passed directly to the passive antenna and allows the tag to transmit the programmed command to the RFID tool. The command is then decoded and processed within the tool and then acted upon. The command can include logic to tell the tool to function immediately, function after a delay, or switch operating modes to look for another trigger. The small size of the tag allows freedom of movement and easy integration with existing completions. Because RFID transmission is a close-proximity means of transferring data, it requires no direct contact between both devices. The communication can be made in a downhole context at up to 6 to 12 in. RFID technology has so far been used in drilling applications, in upper-completion equipment, and in the reservoir as an inflow-control-device sleeve or for providing a multizone stimulation sys-tem in slickwater or hydraulic proppant.

Application of Direct Metal Laser Sintering to Waveguide-Based Passive Microwave Components, Antennas, and Antenna Arrays

Direct metal laser sintering (DMLS), sometimes used interchangeably with the term direct metal sintering (DMS), is an additive manufacturing (AM) technique of synthesizing metallic parts from metal alloy powder. This paper looks at the application of DMLS to waveguide-based passive microwave components, antennas, and antenna arrays. Communication or radar systems use waveguide-based components and antennas to transport and manipulate radio-frequency (RF) power because they are arguably the most efficient. However, they are mostly used only in selected high-performance systems, especially at frequencies at X-band and Ku-band, because they are costly and difficult to fabricate as specialized processes like dip brazing, electron beam welding, and electroforming are needed for making complicated parts. The advent and the maturing of the DMLS technology may revive the fortunes of waveguide-based components and antennas as designs that are previously difficult to fabricate can be now easily handled. Furthermore, as DMLS continues to become more affordable, its versatility means that a microwave or antenna engineer can now leverage on DMLS to design very efficient novel microwave components and antennas that are previously difficult to fabricate or not even practical previously.

Experimental Investigations of a Novel Lightweight Blade Antenna for UAV Applications [Antenna Applications Corner

Small, lightweight, and broadband antennas are a growing need for unmanned aerial vehicle (UAV) platforms due to the increasing demand of highly integrated systems for both electronic warfare (EW) and communication-oriented applications. In this article, an experimental characterization of a compact printed passive wide-band dipole antenna is presented. The main advantages of this design are the reduction of both the height and the weight of the antenna while keeping the structure as tough as possible from an environmental point of view with the only drawback being a tradeoff with respect to voltage-standing wave ratio (VSWR) performances. The simplicity (no lumped passive components are used to match the antenna input impedance to 50 X) and performance effectiveness of the proposed antenna is such that it avoids a complicated screening process among different phase-matched sets of radiating elements. The experimental characterization was performed through a near-field measurement setup, showing excellent agreement with numerical fullwave simulations.

A Passive Temperature-Sensing Antenna Based on a Bimetal Strip Coil.

A passive temperature-sensing antenna is presented in this paper, which consists of a meandering dipole, a bimetal strip and a back cavity. The meandering dipole is divided into two parts: the lower feeding part and the upper radiating part, which maintain electric contact during operation. As a sensing component, a bimetal strip coil offers a twisting force to rotate the lower feeding part of the antenna when the temperature varies. As a result, the effective length of the dipole antenna changes, leading to a shift of the resonant frequency. Furthermore, a metal back cavity is added to increase the antenna’s quality factor Q, which results in a high-sensitivity design. An antenna prototype is designed, fabricated, and measured, which achieves a sensitivity larger than 4.00 MHz/°C in a temperature range from 30 °C to 50 °C and a read range longer than 4 m. Good agreement between the simulation and measurement results is obtained.

Cavity-backed metasurface antennas and their application to frequency diversity imaging.

Frequency diversity antennas with spatially structured radiation patterns reduce the reliance on actively switched elements for beamforming which become increasingly expensive and impractical as frequency increases. As the quality factor Q of a frequency diverse antenna increases, the antenna samples more spatial structure as the number of unique radiated coded spatial patterns correspondingly increases. Antennas that combine hollow cavities and metamaterial apertures achieve both large fractional bandwidth, in excess of 40%, and a high Q of 1600, so that each antenna radiates over 640 unique coded patterns. As compared to switched active antennas, such a passive antenna replaces the 50 antennas and switches that would produce at most (50/2)2=625 unique patterns. Furthermore, the engineered metamaterial apertures enable a radiation efficiency exceeding 60% to be achieved in a single desired polarization. The theory of cavity-backed metasurface antennas is explained, and frequency diverse imaging is demonstrated with a pair of these antennas.

Radio Frequency Identification (RFID) Tag Antenna Design at Ultra High Frequency (UHF) Band

This project is to design a Radio Frequency Identification (RFID) high sensitivity tag antenna which operates at UHF frequency band in Malaysia between 919 MHz to 923 MHz. RFID is a type of wireless and radio wave technology that allows for a small RFID chip to be embedded in certain physical object and uniquely identified by an RFID reader. The major contempilation is that the tag antennas will have longer read ranges but in small sizes. While reducing the size of these antennas cause gain decrease will cause reduction in the read range. Another challenge in designing passive RFID tags antennas is to have the highest impedance matching to achieve high efficiency and low effects of the electromagnetic environment. This project was providing two methods to overcome those problems. Firstly, construct meander line structure to reduce the antenna size and design proposed tag antenna with T-match circuit to achieve conjugate matching with the application-specific integrated circuit so that the reading range of the RFID tag is greatly enhanced. On the other hand, the result show the tag directivity and gain was meets the RFID tag design requirements. This project is useful to be implemented in the RFID industry based on today’s technology.

A Review of Passive RFID Tag Antenna-Based Sensors and Systems for Structural Health Monitoring Applications.

In recent few years, the antenna and sensor communities have witnessed a considerable integration of radio frequency identification (RFID) tag antennas and sensors because of the impetus provided by internet of things (IoT) and cyber-physical systems (CPS). Such types of sensor can find potential applications in structural health monitoring (SHM) because of their passive, wireless, simple, compact size, and multimodal nature, particular in large scale infrastructures during their lifecycle. The big data from these ubiquitous sensors are expected to generate a big impact for intelligent monitoring. A remarkable number of scientific papers demonstrate the possibility that objects can be remotely tracked and intelligently monitored for their physical/chemical/mechanical properties and environment conditions. Most of the work focuses on antenna design, and significant information has been generated to demonstrate feasibilities. Further information is needed to gain deep understanding of the passive RFID antenna sensor systems in order to make them reliable and practical. Nevertheless, this information is scattered over much literature. This paper is to comprehensively summarize and clearly highlight the challenges and state-of-the-art methods of passive RFID antenna sensors and systems in terms of sensing and communication from system point of view. Future trends are also discussed. The future research and development in UK are suggested as well.

Possibilities of Fabricating Copper-based RFID Tags with Photonic-sintered Inkjet Printing and Thermal Transfer Printing

This letter studies the possibilities of manufacturing copper-based passive ultrahigh frequency (UHF) radio frequency identification (RFID) tags using inkjet and thermal printing on two substrate materials, polyimide (Kapton), and a polyester-based substrate (Flexcon THERMLfilm). Both printing methods are tested to fabricate different tag designs, and the performance of successfully printed tags is evaluated using wireless measurements. Measurement results show that both printing methods, while using copper material, can be used to effectively fabricate passive UHF RFID tag antennas on selected substrates.

Experimental Study on Strain Reliability of Embroidered Passive UHF RFID Textile Tag Antennas and Interconnections

We present embroidered antennas and interconnections in passive UHF RFID textile tags and test their strain reliability. Firstly, we fabricate tag antennas on two different stretchable fabric substrates by five different embroidery patterns and choose the most stretchable ones for testing. Next, the tag ICs are attached by sewing and gluing, and the tag reliability during repeated stretching cycles is evaluated through wireless measurements. Initially, the chosen tags achieve read ranges of 6–8 meters and can strain up to 140–150% of their original length. After 100 stretching cycles to 80% of their maximum strain, the read ranges of the tags with glued interconnections are similar to the initial values. In addition, also the read ranges of the tags with sewed interconnections are still more than 70%–85% of their initial values. However, some challenges with the reproducibility need to be solved next.

An Eigenvalue Perturbation Solution for the Multi-Physics Simulation of Antenna Strain Sensors

To simulate the behavior of a passive antenna strain sensor, current multiphysics coupled simulation (between mechanics and electromagnetics) has mainly adopted the frequency domain solution. For every frequency point in the sweeping range, the frequency domain solver computes the value of scattering parameter S11. The S11 curve is used to identify the new resonance frequency when the antenna sensor is at certain strain level. As a result, the frequency domain solution is computationally expensive. In this study, an eigenfrequency solution, whose efficiency is shown to be much higher than the frequency domain solver, is proposed to directly detect changes of antenna resonance frequency under strain. Toward the eigenfrequency solution, cavity and partially air-filled cavity FEM modeling techniques are proposed to reduce the number of degrees of freedom. In addition, by formulating the eigenfrequency solution as an eigenvalue perturbation problem, Rayleigh quotient iteration and the inverse power iteration method with Rayleigh quotient are proposed to further improve the computational efficiency. The proposed methods will greatly improve the efficiency of antenna sensor designs.

A method for measuring dynamic radiation patterns of passive and active phased antenna arrays

The study deals with a method for measuring dynamic radiation patterns of phased antenna arrays and active phased antenna arrays. The method consists of measuring the signal during electronically scanning the beam of a static antenna. We show the main differences between dynamic and static radiation patterns. The Whittaker Nyquist – Kotelnikov – Shannon sampling theorem forms the basis of our recommendations for selecting the number of measurement points in the case of a dynamic radiation pattern. We supply a diagram of a work station dedicated to measuring dynamic radiation patterns using the workbench developed by the Joint-stock company “V. Tikhomirov Scientific Research Institute of Instrument Design”. We present measured static and dynamic radiation patterns of a real-world active phased antenna array.Our method for measuring dynamic radiation patterns significantly decreases the time required for determining radiation characteristics of phased antenna arrays and active phased antenna arrays for separate angular cross-sections and over the whole visibility scope, and increases their information content. Moreover, measuring dynamic radiation patterns does not require a rotating workbench. It is possible to use dynamic radiation pattern to determine static (as measured by turning the antenna) far-field patterns, to restore electric current magnitude and phase distribution over the aperture and to troubleshoot the antenna.

Multiband compact antenna for near‐field and far‐field RFID and wireless portable applications

This study presents a multiband compact microstrip antenna for portable wireless applications. The proposed antenna, in addition to wireless local area network and a global positioning system (GPS) channels, is utilised for inductive and capacitive near- and far-field ultrahigh-frequency and 2.4 GHz radio frequency identification (RFID) applications. The fabricated antenna works at 890 to 933 MHz, GPS-L1, and 2.4 GHz. Its linearly polarised radiation pattern provides a 1.2 to 2.5 dBi gain through the antenna bandwidth. A comparative study with other passive RFID reader conventional antennas shows that the proposed structure provides strong near E- and H-fields and simultaneous good impedance matching for far-field applications. Design details, simulated results, and a fabricated prototype are presented. The experimental results including radiation patterns, peak gain, and efficiency of the proposed antenna are presented. Comparisons between the simulation and measurement results show that the proposed antenna has a reasonable gain and radiation patterns.

Gain and Noise Analysis of Non-Foster Matched Antennas

Non-Foster matching networks can overcome the gain-bandwidth limitations of passive small antennas, but at the cost of increased noise generated by the active matching circuit. Gain and noise measurements of a non-Foster matched small loop antenna were compared with those of the passive loop antenna to quantify the improvement in received signal-to-noise ratio (SNR) with non-Foster matching. The average gain improvement of 7 dB from 30–135 MHz was accompanied by an average added noise of 8.9 dB, indicating that the non-Foster matched antenna did not provide any improvement in the received SNR compared with the passive antenna. These results led to a study of the various noise sources in a non-Foster receiving system. Noise models were developed for the balanced and unbalanced Linvill negative impedance convertor circuits and verified with simulations. Simulations were then done to analyze the noise figure (NF) of a non-Foster receiving system for various small antennas, different biasing conditions, and receiver noise levels. These were then compared with NF simulations of small antennas attached to an amplifier and a noisy receiver. The results indicate that for receivers with low-noise floor levels, a receiving system consisting of a passive small antenna and an amplifier can provide better SNRs compared with a receiving system with a non-Foster matched small antenna.

Surface-Current Measurements as Data for Electromagnetic Imaging Within Metallic Enclosures

A 3-D microwave imaging method within metallic enclosures is investigated and improved. This method uses the components of the surface-current vector at receiver points on the enclosure wall as data. At the metallic wall, the normal component of the magnetic field as well as the tangential components of the electric field is negligible, whereas the vectorial surface current, which is directly related to the tangential components of the magnetic field, is dominant. After presenting the results of a numerical investigation based on synthetic data, the method is validated using an experimental system comprised of 24 co-resident shielded, coaxial half-loop antennas, distributed in four layers, within a cylindrical metallic enclosure. These antennas are used in receiver–transmitter pairs to introduce an electromagnetic field into the chamber and collect the magnetic field at the receiver points. The measured data are used as input to a multiplicatively regularized finite-element contrast source inversion algorithm. Due to their relatively small size and minimal protrusion into the chamber, these antennas minimally perturb the field distribution inside the chamber and thereby allow the use of a simple numerical inversion model, which does not need to account for the passive antennas. These attributes are especially useful for large computationally intensive industrial applications. The experimental system described herein is a laboratory-scale prototype for a stored-grain imaging application where metallic silos are utilized.