Shape Of Antenna Research Articles

CPW - fed dodecagon ring shape antenna for ultra wide band application

The paper presents a coplanar waveguide (CPW)–fed compact ultra wideband (UWB) dodecagon ring shape microstrip antenna. The proposed antenna consists of dodecagon ring radiating patch in place of a conventional annular ring microstrip antenna (ARMSA) to achieve UWB. The proposed antenna is simulated through Ansoft's high frequency structure simulator (HFSS v. 14.0). The measured result shows good agreement with the simulated results. The prototype is taken with dimensions 47 mm × 47 mm × 1.6 mm that achieves good return loss, peak gain (8 dBi) and good radiation patterns over the entire operating bandwidth of 2.18 to 13.76 GHz (11.58 GHz) with 145% of impedance bandwidth at 7.97 GHz centre frequency. Thus, the proposed antenna is applicable for numerous wireless applications.

CPW - fed dodecagon ring shape antenna for ultra wide band application

CPW - fed dodecagon ring shape antenna for ultra wide band application

Miniaturized UWB multi-resonance patch antenna loaded with novel modified H-shape SRR metamaterial for microspacecraft applications

We present the design and analysis of a novel modified H-shaped split ring resonator (SRR) metamaterial. It has negative permeability and permittivity characteristics with multi-band resonance for the X, Ku, and Ka frequency bands. Different configurations of the patch antenna have been analyzed with different orientations and positions of the metamaterial. Optimized performance was achieved with the new shape of the metamaterial antenna with an appreciable 9 dB gain, 77 GHz bandwidth, 100% radiation efficiency, and 65% reduction in active area. The second-order fractal metamaterial antenna achieves high miniaturization on the order of 1/21. This is truly a boon in the communications world, as a sharp beam with smaller physical dimensions is urgently required.

On Methods to Determine Bounds on the $Q$ -Factor for a Given Directivity

This paper revisit and extend the interesting case of bounds on the Q-factor for a given directivity for a small antenna of arbitrary shape. A higher directivity in a small antenna is closely connected with a narrow impedance bandwidth. The relation between bandwidth and a desired directivity is still not fully understood, not even for small antennas. Initial investigations in this direction has related the radius of a circumscribing sphere to the directivity, and bounds on the Q-factor has also been derived for a partial directivity in a given direction. In this paper we derive lower bounds on the Q-factor for a total desired directivity for an arbitrarily shaped antenna in a given direction as a convex problem using semi-definite relaxation techniques (SDR). We also show that the relaxed solution is also a solution of the original problem of determining the lower Q-factor bound for a total desired directivity. SDR can also be used to relax a class of other interesting non-convex constraints in antenna optimization such as tuning, losses, front-to-back ratio. We compare two different new methods to determine the lowest Q-factor for arbitrary shaped antennas for a given total directivity. We also compare our results with full EM-simulations of a parasitic element antenna with high directivity.

The Pointing Self-calibration Algorithm for Aperture Synthesis Radio Telescopes

Abstract This paper is concerned with algorithms for calibration of direction-dependent effects (DDE) in aperture synthesis radio telescopes (ASRT). After correction of direction-independent effects (DIE) using self-calibration, imaging performance can be limited by the imprecise knowledge of the forward gain of the elements in the array. In general, the forward gain pattern is directionally dependent and varies with time due to a number of reasons. Some factors, such as rotation of the primary beam with Parallactic Angle for Azimuth–Elevation mount antennas are known a priori. Some, such as antenna pointing errors and structural deformation/projection effects for aperture-array elements cannot be measured a priori. Thus, in addition to algorithms to correct for DD effects known a priori, algorithms to solve for DD gains are required for high dynamic range imaging. Here, we discuss a mathematical framework for antenna-based DDE calibration algorithms and show that this framework leads to computationally efficient optimal algorithms that scale well in a parallel computing environment. As an example of an antenna-based DD calibration algorithm, we demonstrate the Pointing SelfCal (PSC) algorithm to solve for the antenna pointing errors. Our analysis show that the sensitivity of modern ASRT is sufficient to solve for antenna pointing errors and other DD effects. We also discuss the use of the PSC algorithm in real-time calibration systems and extensions for antenna Shape SelfCal algorithm for real-time tracking and corrections for pointing offsets and changes in antenna shape.

Self-optimization of plasmonic nanoantennas in strong femtosecond fields

Plasmonic dimer nanoantennas can significantly boost the electric field strength in the gap region, allowing for a modification of the feed gap geometry by femtosecond laser illumination. Using resonant bowtie antennas to enhance the electric field of a low-fluence femtosecond oscillator, here we experimentally demonstrate highly localized reshaping of the antennas, resulting in a self-optimization of the antenna shape. From high-resolution scanning electron micrographs and two-dimensional energy dispersive x-ray maps, we analyze the near-field enhanced subwavelength ablation at the nanotips and the resulting deposition of ablated materials in the feed gap. The dominant ablation mechanism is attributed to the nonthermal transient unbonding of atoms and electrostatic acceleration of ions. This process is driven by surface plasmon enhanced electron emission, with subsequent acceleration in the vacuum. This ablation is impeded in the presence of an ambient gas. A maximum of sixfold enhancement of the third-harmonic yield is observed during the reshaping process.

Bandwidth Enhancement of a Micro-strip Patch Antenna with Corner Truncated and U Shape Antenna for Wireless Communications

Bandwidth Enhancement of a Micro-strip Patch Antenna with Corner Truncated and U Shape Antenna for Wireless Communications

Multiport Circular Polarized RFID-Tag Antenna for UHF Sensor Applications.

A circular polarized patch antenna for UHF RFID tag-based sensor applications is presented, with the circular polarization (CP) generated by a new antenna shape, an asymmetric stars shaped slotted microstrip patch antenna (CP-ASSSMP). Four stars etched on the patch allow the antenna’s size to be reduced by close to 20%. The proposed antenna is matched with two RFID chips via inductive-loop matching. The first chip is connected to a resistive sensor and acts as a sensor node, and the second is used as a reference node. The proposed antenna is used for two targets, serving as both reference and sensor simultaneously, thereby eliminating the need for a second antenna. Its reader can read the RFID chips at any orientation of the tag due to the CP. The measured reading range is about 25 m with mismatch polarization. The operating frequency band is 902–929 MHz for the two ports, which is covered by the US RFID band, and the axial-ratio bandwidth is about 7 MHz. In addition, the reader can also detect temperature, based on the minimum difference in the power required by the reference and sensor.

Millimeter-Wave Beam Training Acceleration Through Low-Complexity Hybrid Transceivers

Millimeter-wave (mm-wave) communication systems can provide much higher data rates than systems operating at lower frequencies, but achieving such rates over sufficiently large distances requires highly directional beamforming at both the transmitter and receiver. These antenna beams have to be aligned very precisely in order to obtain sufficient link margin. In this paper, we first propose a parallel-adaptive beam training protocol, which significantly accelerates the link establishment between mm-wave devices by exploiting the ability of hybrid analog-digital beamforming antennas to scan multiple spatial sectors simultaneously. Second, we deal with practical constraints of the mm-wave transceivers and design a novel greedy geometric algorithm to synthesize sector beam patterns featuring configurable beamwidth and multi-beam radiation as required by the proposed beam training protocol. These multi-beam patterns are then also used for concurrent data communication over multiple paths, in case several suitable directions are found during the beam training. Simulation results show that our algorithm is able to shape antenna patterns very close to those attained by a fully digital beamforming architecture, yet requires lower complexity hardware compared with the state-of-the-art solutions. Exploiting such multi-beam antenna patterns, our parallel beam training protocol can provide up to 82% effective rate increase and 70% search time decrease compared with existing sequential protocols. The acceleration of the beam training phase shifts the optimum balance between the search overhead and the achieved directivity gain so that the best performance is reached with a training load 30% to 60% lower than that of the sequential beam training.

Investigated the Fano resonance in the nano ring arrangement

Field enhancement in Plasmonic and FANO mode at nano antennas are noticed recently, here, we are modeled a nano antenna for achieving Fano resonance and for this aim, we are made asymmetric formation in nano ring structure and studied the parametric effects on Fano resonance controlling. We have debated on E-field enhancements at resonances with comparison the parameters effect on Fano resonance energy. We show that the single ring has plasmonic mode and adding an inner ring made Fano resonance and shows that the energy in dark mode is increased drastically. Here, the study of the inner ring position is indicated that how the bright mode and dark mode have appeared in nano antenna. Figure of merit (FOM) is studied for different additional material effects on prototype structure and Δ(E) variation is noticed. The structure is modeled with FDTD simulation by the CST microwave studio and for substrate; we selected SiN with a thickness of 40nm. Here for achieving dark mode energy, novel shape of the dual ring nano antenna is suggested for concentration of the energy in small point to increase the interaction between nano particle and bio-particle.

Development and characterization of flexible antenna based on conductive metal pattern on polyester fabric

Current paper focuses on the development and characterization of flexible antenna based on conductive metal pattern on polyester fabric. The flexible fabric patch antenna was prepared by printing of metallic patterns on fabric textures through a multi-step process. The inkjet printing followed by electroless nickel plating methods were employed to coat different patch sizes and shapes with extremely high conductivity on insulated fabric. The scanning electron micrograph imaging technique confirms the formation of Ni nanoparticle with normal distribution and average size of 150 ± 20 nm. The EDAX analysis reveals more than 93%w/w Ni which supports the high four-point probe conductivity of 2500 ± 175 S/cm for antenna patterns. The X-ray diffraction pattern also indicates the amorphous nickel formation and randomly phosphorus atoms trapped between the nickel atoms. Also, the measured results evidence that the tensile strength of the textile Antenna shows an increase of 25.72% in the warp direction and 19.98% in the weft direction. Also the amount of flexural stiffness significantly improves and the wrinkles reduced after electroless plating. Also the antenna’s gain and bandwidth were studied by spectrum analyzer and the coated film surfaces. The largest printed patch antenna experienced a significant increase of about 1 kHz in bandwidth and −3 dB increase in gain value compared to other antennas. Also, the rectangular shape antenna showed a peak value at bandwidth of 4.2 kHz and gain value of −0.1 dB in comparison with spiral antenna.

Flexible plasma linear antenna

In this work, we introduce a type of plasma antenna that was fabricated using flexible materials and excited using a 5−20 kHz alternating current (ac) power supply. The results showed that the antenna characteristics, including the impedance, the reflection coefficient (S11), the radiation pattern, and the gain, can be controlled rapidly and easily by varying both the discharge parameters and the antenna shapes. The scope for reconfiguration is greatly enhanced when the antenna shape is changed from a monopole to a helix configuration. Additionally, the antenna polarization can also be adjusted by varying the antenna shapes.

Linear/circular polarizations slot antennas for millimmiter wave applications

This article describes three different types of broad multiband linearly and circularly polarized slot antennas (rectangular, circular, and triangular shaped slot) for millimeter wave wireless communication applications. Proposed antennas consist of a slot radiator on the top metal layer and coupled to a rectangular dielectric resonator above the slot. The conventional microstrip-line-feed is used for different shapes of slot antennas. An high frequency structure simulator, finite element method (FEM)-based, three-dimensional full wave electromagnetic solver simulator by ANSYS was used for the design of the proposed antennas. The final antennas were fabricated and their characteristics were measured. The bandwidth of |S11| <−10 dB was extended from 19.5 GHz up to 75 GHz. This band covers most of wireless MM-wave applications, fifth Generation mobile and wireless networks, and the WLAN, WPAN, and W-bands. The simulated and measured radiation efficiency, gain, and radiation pattern of the proposed antennas are presented. The average radiation efficiency and gain over the entire operating band are about 60% and 6 dBi, respectively. These antennas are also low profile and low cost. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:976–983, 2017

Optimal Performance of Epidermal Antennas for UHF Radio Frequency Identification and Sensing

Skin-mounted electronics is the new frontier for unobtrusive body-centric monitoring systems. In designing the wireless devices to be placed in direct contact with the human skin, the presence of the lossy body cannot be ignored because of strong electromagnetic interactions. In this paper, the performance of epidermal antennas, for application to radio frequency identification (RFID) links in the UHF band, was investigated by means of numerical simulations and laboratory tests on fabricated prototypes. The analysis demonstrates the existence of an optimal size of the antennas (from 3 to 6 cm for loops and from 6 to 15 cm for dipoles) and of upper bounds in the achievable radiation gain (less than −10 dB in the case of 0.5 mm thick application substrates) as a consequence of the balance between the two opposing mechanisms of radiation and loss. This behavior, which is controlled by the hosting medium, does not depend on the antenna shape, even if the loop layout permits considerably minimizing the device size. Even the conductivity of the antenna trace plays only a second-order role; low-cost inkjet printable paints with conductivity higher than 104 S/m are suitable to provide radiation performance comparable with the performance of copper-made antennas. Starting from the investigation of the above cited physical phenomena, including the effect of common classes of suitable substrate membranes, guidelines are finally derived for the optimal design of real RFID epidermal antennas.

Novel optical polarizer design based on metasurface nano aperture for biological sensing in mid-infrared regime

Since Metasurfaces are playing important roles in optical devices such as optical polarizers and detectors, in this article, we have proposed a novel shape of nano aperture antenna for mid-infrared applications such as bio-sensing and other potential optical applications based on plasmonic characteristic of the gold layer over the SiN substrate. The transmittance tensor is obtained for vertical and horizontal linear polarization and base on boundary condition of the metasurface, the circular polarizations are extracted which are confirmed by the electric field distributions. We have shown by the parametric studies that the phase difference is altered by the gap and slot width and so with the dimension modification, we are able to achieve circular polarizer in the optical range. The biological materials with a thickness of 80 nm have then been placed over the metasurface layer and the figures of merits have been obtained. We have revealed that when the circular polarization is osculated to the metasurface at a special frequency the linear polarization is obtained in the other side of the metasurface. The nano aperture has been modeled and the finite difference time domain calculations are performed in CST Microwave Studio as a commercial full wave simulation software.

Dual Band Notched EBG Structure based UWB MIMO/Diversity Antenna with Reduced Wide Band Electromagnetic Coupling

AbstractA dual band-notched MIMO/Diversity antenna is proposed in this paper. The proposed antenna ensures notches in WiMAX band (3.3–3.6 GHz) besides WLAN band (5–6 GHz). Mushroom Electromagnetic Band Gap (EBG) arrangements are employed for discarding interfering frequencies. The procedure followed to attain notches is antenna shape independent with established formulas. The electromagnetic coupling among two narrowly set apart Ultra-Wide Band (UWB) monopoles is reduced by means of decoupling bands and slotted ground plane. Monopoles are 90° angularly parted with steps on the radiator. This aids to diminish mutual coupling and also adds in the direction of impedance matching by long current route. S

Comparative morphology of two species of Caraguata Bechyné (Coleoptera, Chrysomelidae, Galerucinae, Galerucini)

ABSTRACT. Caraguata Bechyne, 1954 (Galerucini, Galerucina) includes 38 species exclusively Neotropical, among them two sympatric species, C. atricornis (Clark, 1865) and C. guaporensis Bechyne, 1958. Given the lack of morphological studies in this group, we aimed to characterize the adult morphology of two species, providing descriptions, illustrations and comparisons of structures of the head, thorax, abdomen and genitalia. The external morphology includes the description of head, thorax, abdomen and its appendices; the internal morphology comprises endosternites, and male and female genitalia. Some similarities were observed, such as pubescence, mouth parts, apparent sexual dimorphism on ventrite V, spermatheca and vaginal palpi. The main diff erences are in (1) the body and antenna shape, (2) the antenna color pattern, (3) the depression of the pronotum, (4) the presence/absence of the tibial spur, (5) the form of the median lobe, (6) the tegmen and (7) the sternite VIII of the females. The morphological study of these species contributes to the knowledge of Galerucina, presenting important specifi c characteristics not employed until now. Thus, it can be a contribution for studies of comparative morphology, systematics and evolution of the group.KEYWORDS. Galerucina, Neotropical, Coelomerites, genitalia.

Compact Omnidirectional Conformal Array Antenna in Waveguide Technology

A conformal array antenna has been designed in the waveguide technology in order to obtain an omnidirectional radiation pattern in the azimuth plane at the Ku-band. The antenna shape is a regular prism, where the single radiating elements, which consist of a rectangular waveguide ended on a cavity–slot, are placed on the planar faces of the prism. The physical dimensions as well as the number of faces of the regular prism have been optimized following the conformal array formulation in order to achieve a minimum ripple omnidirectional pattern. An eight-faced regular prism with an apothem of 20.6 mm has been selected as the radiating structure. The single elements are fed by an eight-way radial waveguide power divider symmetrically excited by a 50-Ω SMA input port. The use of waveguide technology to design the single elements and the feeding network makes the conformal array suitable for low losses and high-power applications. Several prototypes have been manufactured in order to experimentally validate the antenna performance. An omnidirectional pattern with a maximum ripple of 1.6 dB in the azimuth plane, 95.3% efficiency, and 11.7% input matching bandwidth has been measured.

Evaluation of thermal-deformation reduction method through prototyping space antenna's shape control mechanisms

Evaluation of thermal-deformation reduction method through prototyping space antenna's shape control mechanisms

A Feasible Novel Technique for Breast Cancer Imaging Using UWB-Microwave Antennas

Microwave Imaging (MI) of breast cancer is an emerging non-invasive and non-ionizing technique for breast cancer diagnosis based on microwave radiation backscattered by breast tissues. Usually, MBI explore dielectric properties of breast tissues to increase the imaging contrast between tumor and healthy tissue through an Inverse Image Reconstruction Algorithm. Furthermore, MBI systems could be cost-effectively, compact and recent developments drive them to wearable soon. Even X-ray Mammography is the gold-standard for imaging tumors inside breast; it still is low contrast for early diagnostic, painful and age- and dose-restricted because ionizing radiation. Then, in long-term, our group is motivated to develop MBI technique and cost-effectively wearable systems for in vivo early diagnosis of breast cancer as a complimentary to X-ray Mammography. In short-term, we had been designing our systems by simulations, manufacturing and initial in vitro tests in lab. This work presents initial results of design and simulation of a system based on hard and/or flexible antennas ranging between 0.001 GHz to 3 GHz for in vitro experimentation. In detail, two different shapes (rectangular patch and circular slot) of Micro strip Patch antennas were designed and simulated in FR4, Cotton, Polyester and Pyralux Polyimide (for Flexible antennas) materials. The resonance frequency of antennas depends on permittivity of substrate material and its geometry, so the High Frequency Simulation Software (HFSS) simulated scattering parameters of designed antennas, which were also tested on mimic-phantoms of breast. The simulation of rectangular patch and bow-tie antennas resulted on a like-Gaussian curve of microwave emission / detection peaked at 1.9-2.7 GHz with ~50-90MHz band width.