Yagi-Uda Antenna Research Articles

Design and Characterization of High Efficiency Nanoantenna Couplers With Plasmonic Integrated Circuit

Four types of nanoantennas have been designed and characterized at 1.55 μ m wavelength: Dipole antenna, Yagi-Uda antenna, dipole antenna array and bowtie antenna. The spectra, coupling efficiency, and far field radiation patterns are also investigated. We also quantitatively characterized the relationship between the couple-in efficiency and the spot size of the incident light. For the three dipole-type antennas, the couple-in and couple-out efficiencies have been measured experimentally. A plasmonic integrated circuit has also been designed and fabricated with these four types of nanoantennas. Direct and efficient optical coupling from an optical fiber into the plasmonic integrated circuit is demonstrated as well, and the couple-out efficiencies for these four nanoantennas are.

EBG-Backed Flexible Printed Yagi–Uda Antenna for On-Body Communication

An electromagnetic bandgap (EBG) structure backed, printed Yagi-Uda antenna for on-body communication is proposed in this communication. The proposed antenna is flexible, made of copper foil tape and polyester sheet. The antenna operates at 2.4-GHz industrial, scientific and medical radio band. A printed Yagi-Uda is used to achieve high gain, endfire radiation pattern, and decreased path loss. An EBG surface is also used to reduce the frequency detuning of the antenna and specific absorption rate (SAR) while increasing the antenna gain when placed on human body. Antenna gain has been increased by 60%, and SAR has been decreased from 8.55 to 0.07 W/kg when the antenna is backed with EBG.

A dual-band reconfigurable Yagi–Uda antenna with diverse radiation patterns

In this paper, a dual-band pattern reconfigurable antenna is proposed. The antenna comprises of a dual-band complementary split ring resonators (CSRRs) loaded dipole as the driven element and two copper strips with varying lengths as parasitic segments on both sides of the driven dipole. PIN diodes are used with the parasitic elements to control their electrical length. The CSRRs loading provide a lower order mode in addition to the reference dipole mode, while the parasitic elements along with the PIN diodes are capable of switching the omni-directional radiation of the dual-band driven element to nine different configurations of radiation patterns which include bi-directional end-fire, broadside, and uni-directional end-fire in both the operating bands. A prototype of the designed antenna together with the PIN diodes and DC bias lines is fabricated to validate the concept of dual-band radiation pattern diversity. The simulation and measurement results are in good agreement. The proposed antenna can be used in wireless access points for PCS and WLAN applications.

Design of Polyimide-Coated Yagi-Uda Antennas for Monitoring the Relative Humidity Level

Coating an antenna with a hydrophilic polyimide film has been reported to enhance the effects of atmospheric relative humidity on the characteristics of the antenna. In this letter, we designed Yagi-Uda antennas with polyimide-coated dipoles, and we performed a simulation study investigating the influence of atmospheric relative humidity on their resonant frequencies. We conclude that antennas of this type might constitute viable sensors for the measurement of atmospheric relative humidity, and hypothesize that in certain situations such sensors may have advantages over existing alternatives.

Wideband excitation technology of substrate integrated waveguide TE 30 mode and its antenna application

An excitation technology of TE 30 mode in substrate integrated waveguide (SIW) and its application for designing a compact Yagi-Uda antenna array is proposed. Coplanar waveguide (CPW) structure is adopted as the input and two slots of CPW are further extended in the SIW along the third lines in the longitudinal direction to convert the electromagnetic field pattern between the slot and SIW. Therefore, TE 30 mode is successfully excited. A Yagi-Uda antenna array fed by the SIW operating at TE 30 mode is fabricated and measured. A broad impedance bandwidth of 46% (| S 11 | <; -10 dB) ranging from 7.8 to 12.4 GHz is achieved with obtaining a maximum gain of 8.5 dBi. Compared with the traditional SIW antenna array based on TE 10 mode, the higher mode excitation technology not only simplifies the feeding network but also reduces the difficulty of processing.

Highly efficient light extraction and directional emission from large refractive-index materials with a planar Yagi-Uda antenna

Light emission is a basic process at the core of applications in optics and photonics, such as lighting, sensing and telecom. Despite extensive work on the design of light-matter interfaces, the outcoupling of electromagnetic radiation from nanoscale sources is still a challenge. Here, we show how a planar Yagi-Uda antenna based on thin-film optics can lead to more than 90% outcoupling efficiency and strong directional emission from materials with a large refractive index. Our findings are particularly relevant for semiconductor-based nanophotonic devices, which typically suffer from a large mismatch with respect to free-space and guided modes.

Video Monitoring Application using Wireless Sensor Node with Various External Antenna

&lt;p&gt;Surveillance and monitoring has become very important for security reasons these days. The use of wireless sensor node device offers a variety of platform depends on the attached sensor. When an image sensor is attached, the wireless sensor node is capable of monitoring an area wirelessly. Since wireless environment uses antenna to transmit and receive data, antenna is an important component that affects the video monitoring performance. This paper describes a surveillance system using Raspberry Pi with various external antenna. The Raspberry Pi with Pi Camera module and various types of antennas was used for testing and experimentation in line-of-sight (LOS) and non-line-of-sight (NLOS) condition. The results revealed that the Yagi Uda antenna gives the best output in terms of its signal strength and average Receive (Rx) rate.&lt;em&gt;&lt;/em&gt;&lt;/p&gt;

Beam-Scanning Reflectometer for Detecting Granulated Fruits

The problem of granulation in fruits costs vendors a big chunk of their revenue, hence a non-destructive sensor that can identify granulated fruits without destroying good fruits is highly desirable. This paper presents such a sensor system based on beam-scanning reflectometer operating at 2.45 GHz. Beams of scattered waves from several directions around the fruit are reflected by a conical reflector and scanned by a phased array of pattern reconfigurable Yagi–Uda antennas equipped with 1-b phase shifters for lowest loss in feed network. The collected data are used to calculate the Rician $k$ -factor. The system was tested with plasticine spheres and real tangerines. It was found that the system with an eight-beam array was better than one with a four-beam array. This system may prove useful for quality control of tangerines and other agricultural products.

A design of nano-optical Yagi-Uda antenna with high forward directivity

A design of nano-optical Yagi-Uda antenna with high forward directivity

A printed Yagi–Uda antenna for application in magnetic resonance thermometry guided microwave hyperthermia applicators

Biological studies and clinical trials show that addition of hyperthermia stimulates conventional cancer treatment modalities and significantly improves treatment outcome. This supra-additive stimulation can be optimized by adaptive hyperthermia to counteract strong and dynamic thermoregulation. The only clinically proven method for the 3D non-invasive temperature monitoring required is by magnetic resonance (MR) temperature imaging, but the currently available set of MR compatible hyperthermia applicators lack the degree of heat control required. In this work, we present the design and validation of a high-frequency (433 MHz ISM band) printed circuit board antenna with a very low MR-footprint. This design is ideally suited for use in a range of hyperthermia applicator configurations. Experiments emulating the clinical situation show excellent matching properties of the antenna over a 7.2% bandwidth (S11 < −15 dB). Its strongly directional radiation properties minimize inter-element coupling for typical array configurations (S21 < −23 dB). MR imaging distortion by the antenna was found negligible and MR temperature imaging in a homogeneous muscle phantom was highly correlated with gold-standard probe measurements (root mean square error: RMSE = 0.51 °C and R2 = 0.99). This work paves the way for tailored MR imaging guided hyperthermia devices ranging from single antenna or incoherent antenna-arrays, to real-time adaptive hyperthermia with phased-arrays.

Temperature-driven switchable-beam Yagi-Uda antenna using VO2 semiconductor-metal phase transitions

In this study we propose and analyze a temperature driven switchable-beam vertically polarized directional antenna for micro/nano scale optical communications. Temperature enabled phase transitions of a thin layer of vanadium dioxide reshape the beam of a Yagi-Uda antenna by changing the directionality of the radiation pattern and altering the emission rate. The role of each antenna element in the Yagi-Uda array's emission is demonstrated at different temperatures by comparing the amplitudes and phases of induced currents in the elements. Thus a substantial directional gain switching is shown using resonance damping manipulation of antenna elements.

Planar Directional Beam Antenna Design for Beam Switching System Applications

In this paper, a planar directional beam-switchable antenna with four orthogonal beam directions is proposed. The proposed antenna is designed with two crossed active elements and two parasitic elements for each direction. The design methodology is described on the basis of the Yagi-Uda method for the active and parasitic elements, respectively. By adjusting the effective electric lengths of the parasitic elements, the roles of a director and a reflector are exchanged with each other. The planar four-way beam-switchable Yagi-Uda antenna is implemented. From the experimental results. The proposed design method is verified for orthogonal radiation beam switching.

Microwave Power Beaming using Ka-band Radar Tethered Aerostat Program

With electronic devices becoming smaller and more portable, they are being utilized more in science and everyday life. There must be a way to power these devices without long cables, large batteries, or other power supplies. Mobile phones and CubeSats are examples of technologies that could take advantage of wireless low-energy transfer for powering or charging devices. Our platform, containing our receiving circuitry was suspended from a tethered aerostat. The platform was designed to receive the wireless signal emitted from a microwave transmitter, analyze the strength of the signal via a programmable microcontroller, and transmit the data back to our logging station on ground level. In order to receive the transmitted power in a usable state, a rectifier and multiple antennas had to be designed and built to test for reception and efficiency. The antennas designed included the Yagi-Uda and fractal-patch antennas

A Yagi–Uda Antenna With Load and Additional Reflector for Near-Field UHF RFID

In this letter, a Yagi–Uda antenna with load and additional reflector is proposed to achieve strong and uniform magnetic field distribution within the antenna area for near-field ultrahigh-frequency radio frequency identification (RFID). This proposed antenna is composed of one driven dipole to emit electromagnetic (EM) wave, several directors to direct the EM wave to the desired area, a load element at the end of the director array to absorb the wave, and two reflectors at both ends to reflect the EM wave. The proposed antenna can generate a uniform magnetic field distribution within the antenna area, meanwhile keeping the field strength outside the antenna area relatively small. A prototype, as an example, that contains 13 elements is designed and fabricated, with the measured bandwidth of 880–980 MHz. The achieved interrogation area is 440 × 160 mm2, measured by utilizing a commercial RFID reader and some near-field tags. It is worth mentioning that the interrogation area can be extended by adding more directors to the antenna.

Planar Yagi–Uda Antenna Array Based on Split-Ring Resonators (SRRs)

A novel planar Yagi–Uda antenna is presented in this letter. The proposed antenna uses electrically small resonators as radiating elements that behave as short electric dipoles. Its radiation pattern, gain, front-to-back ratio, and efficiency are maintained close to that of a Yagi–Uda antenna of stacked half-wavelength dipoles. However, its physical dimensions are considerably reduced. The choice of the resonant particle and its radiation properties, along with the antenna structure, are discussed. Simulated results show a good impedance matching (–29 dB) at the working frequency of 5.5 GHz for a 15-elements antenna, as well as a high gain (11.5 dBi). These characteristics are experimentally validated and compared to that of other Yagi–Uda designs from the literature.

A Longitudinally Compact Yagi–Uda Antenna With a Parasitic Interdigital Strip

A Yagi–Uda antenna with a parasitic interdigital strip is proposed for a compact design. The parasitic strip is positioned between a driven dipole element and a reflecting element to compensate for the phase change, while high gain and good impedance matching is achieved for the proposed antenna with significant longitudinal reduction. The experimental results show that the proposed two-element Yagi–Uda antenna realizes a gain of 5.1 dBi with the spacing of only 0.06λ0, compared to the conventional spacing of 0.21λ0 (λ0 is the guided wavelength at 1.48 GHz). The overall size of the proposed antenna is 0.57 λ 0 × 0.12 λ0.

Antenna Design and SAR Analysis on Human Head Phantom Simulation for Future Clinical Applications.

BackgroundThe rapid development of a variety of devices that emit Radiofrequency Electromagnetic fields (RF-EMF) has sparked growing interest in their interaction with biological systems and the beneficial effects on human health. As a result, investigations have been driven by the potential for therapeutic applications, as well as concern for any possible negative health implications of these EM energies [1-4]. Recent results have indicated specific tuning of experimental and clinical RF exposure may lead to their clinical application toward beneficial health outcomes [5].MethodIn the current study, a mathematical and computer simulation model to analyze a specific RF-EMF exposure on a human head model was developed. Impetus for this research was derived from results of our previous experiments which revealed that Repeated Electromagnetic Field Stimulation (REMFS) decreased the toxic levels of beta amyloid (Aβ) in neuronal cells, thereby suggesting a new potential therapeutic strategy for the treatment of Alzheimer's disease (AD). Throughout development of the proposed device, experimental variables such as the EM frequency range, specific absorption rate (SAR), penetration depth, and innate properties of different tissues have been carefully considered.ResultsRF-EMF exposure to the human head phantom was performed utilizing a Yagi-Uda antenna type possessing high gain (in the order of 10 dbs) at a frequency of 64 MHz and SAR of 0.6 W/Kg. In order to maximize the EM power transmission in one direction, directors were placed in front of the driven element and reflectors were placed behind the driven element. So as to strategically direct the EM field into the center of the brain tissue, while providing field linearity, our analysis considered the field distribution for one versus four antennas. Within the provided dimensions of a typical human brain, results of the Bioheat equation within COMSOL Multiphysics version 5.2a software demonstrated less than a 1 m˚K increase from the absorbed EM power.

Pattern-Reconfigurable Printed Dipole Antenna Using Loaded Parasitic Elements

A printed dipole antenna is designed with two parasitic elements loaded by embedded resonators to provide reconfigurable patterns. The embedded resonators in the parasitic elements are loaded by varactor diodes, which change the phase and the transmission coefficient responses of the parasitic elements. This allows the parasitic elements to act as either a director, a reflector, or a neutral element. The proposed printed dipole antenna with two loaded parasitic elements acts as a printed Yagi-Uda antenna. Because the parasitic elements can act as either a director or a reflector, the directed gain can be increased, and the front-to-back ratio (FBR) may be improved up to 42 dB. It is also possible to achieve different target FBR if broadcasting is needed in two directions of the boresight. This pattern reshaping can be obtained as quickly as the diodes can change their capacitance. The antenna is designed to operate at 2.4 GHz, but this design approach can be applied to other frequency bands. The simulation and measurement results are in good agreement. © 2016 IEEE.

A differential‐fed Yagi–Uda antenna with enhanced bandwidth via addition of parasitic resonator

ABSTRACTA printed‐circuit differential‐fed Yagi–Uda antenna is presented that features enhanced bandwidth by employing a parasitic quarter‐wavelength coplanar stripline (CPS) resonator which adds one more resonant mode within the operating bandwidth. The proposed antenna is designed, fabricated and measured. Experimental results are in good agreement with simulations. In the band of 2.27–2.58 GHz, the return loss is better than 10 dB and the gain better than 6 dBi. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:156–159, 2017

Shape Approaches for Enhancing Plasmon Propagation in Graphene

Graphene plasmonics is a promising alternative for on-chip high speed communication that integrates optics and electronics, where the strong confinement of the electromagnetic energy at subwavelength scale and the tunability of the plasmon frequency via an external gate voltage are key advantages. The main drawback of graphene plasmons is their rather short decay and propagation length, which is due to intrinsic losses and substrate-related defects. Toward plasmonic devices, noble metal antennas represent a viable approach for plasmon launching in graphene waveguides, with the challenge of efficient coupling and plasmon propagation that are feasible for on chip communication. Here we discuss and analyze, using numerical simulations, different designs of metal antennas and their coupling to graphene plasmons (GP), as well as graphene based nanopatterned waveguides that can lead to a more efficient GP propagation. A Yagi-Uda antenna leads to stronger coupling to GPs and allows for directive propagation as compared to a simple dipole antenna. This is especially advantageous to launch plasmons in graphene nanowire waveguides, where propagation up to 3 μm and frequency and phase control can be achieved. In tapered graphene waveguides, the constructive interference of the plasmon reflection at the edges can lead to strong plasmon signals up to 8 μm distant from the launching dipole antenna. Nanostructuring of rectangular waveguides into asymmetric chains of truncated triangles greatly enhances directionality of GP propagation and conserves phase information. A comparison of the propagation length and electric near-field strength of these different approaches is presented, and confronted with the efficiency of GP launching by light scattering on scanning near field optical microscopy (SNOM) tips.