Helical Antenna Research Articles

Performance regulation of high-precision wireless passive yarn sensor based on normal mode helical dipole antenna

Stable and reliable sensing performance was required for high-precision wireless passive yarn sensor based on normal mode helical dipole antenna (NMHDA). The actual helical pitch of NMHDA was non-uniform due to manufacturing process, and the previous equivalent impedance model for uniform NMHDA, i.e., wire-loop model, was oversimplified, resulting in inaccurate predicted reactance and sensing performance of yarn sensor. This work combined the circular polarization principle and the asymmetric structure of non-uniform NMHDA to build the wire-loop-wire model. Based on the wire-loop-wire model, the parametric expression of NMHDA impedance and resonant frequency were obtained, and the results predicted by wire-loop model and wire-loop-wire model were compared with the measured one. Furthermore, to demonstrate the practicality of wire-loop-wire model and parametric resonant frequency expression, the impact of helical pitch uniformity on resonant frequency was discussed in terms of the statistical characteristics of prototype helical pitch, and also the parametric expression was applied to design wireless passive yarn sensors with expected working property. It was found that the wire-loop-wire model incorporating the asymmetric structure accurately described the impedance characteristics of the NMHDA with non-uniform helical pitches, and the maximum predicted deviation of resonant frequency was reduced to 1 MHz. The steady long reading range (19.42 ± 0.09 m) of wireless passive yarn sensors prototype demonstrated the capacity of wire-loop-wire model in designing high-precision sensor. Generally, this paper successfully built the wire-loop-wire model for NMHDA with non-uniform helical pitches, and provided a practical tool for designing e-textile devices with NMHDA.

Development of a compact helicon plasma source with two sets of ring array permanent magnets for the study of blue core plasma.

A compact helicon plasma source for the study of helicon plasma, especially for the study of blue core plasma, is designed and developed with permanent magnets (PMs). The structure of the PMs consists of two sets of ring array magnets with opposite magnetization. This structure can provide a higher magnetic field with fewer PMs, which is helpful for controlling the device's mass. A quartz tube with 50cm in length, 5cm in outer diameter, and 0.3cm in thickness is used. Argon helicon plasma is produced at ∼38 sccm (3.4Pa inlet chamber and 0.122Pa diffusion chamber) by a radio frequency (RF) power of ∼13.56MHz using a helical antenna under a high magnetic field (∼1600G). Preliminary results measured by the Langmuir probe, photomultiplier tube (PMT), CCD, and Hall coil are applied to characterize the helicon plasma in this source, such as the mode transition and the formation of the blue core with the RF power variation. The device generates the blue core (W mode) plasma at a lower power of about 200W, and the energy coupling efficiency is as high as 65%.

Microwave Energy Harvesting With No Extra Receiving Antenna

This paper addresses different cases of radio frequency harvesting using different antenna types as 
 transmitting antenna but using just the lead of the capacitor as the wire antenna at the receiving end 
 with a voltage rectifier circuit. Different antennas were used in the input and with two different 
 rectification circuits the conversion efficiencies were studied accordingly. For a source of log periodic 
 antenna, without any antenna, 27.31% RF-DC power conversion efficiency value was obtained at the 
 far-field. For a source of half wavelength dipole antenna, at the near-field, 50.53% RF-DC power 
 conversion efficiency value was obtained. For a source of helical antenna, up to 5 cm distance about 
 14.78% RF-DC power conversion efficiency was observed. For the Yagi-Uda antenna used as a source, 
 RF-DC power conversion efficiency that was obtained at the far was 28.89% without any receiving 
 antenna..

A Circularly Polarized Antenna for UHF Satellite Communication Applications

There is a tremendous demand for antennas with very broad bandwidth and gain so that one antenna can cover the entire frequency range of the satellite communication applications, which are rapidly expanding with the current technology for diverse platforms. Helical antennas are ideal for these applications due to their distinctive qualities such as circular polarization, wide bandwidth, excellent gain, and low-profile conformability. For transmitting and receiving applications, which comprise frequency ranges of 240MHz to 270MHz and 290MHz to 320MHz, respectively. A new design of circularly polarized double-wire helical antenna employing the butterfly approach has been created in this study. An antenna was designed, simulated, analyzed, and fabricated before being experimentally measured for important parameters such as axial ratio, gain, 3dB beamwidth, and voltage standing wave ratio.

Experimental Characterization of a Helical Antenna Integrated in the Rear of a Vehicle for C-V2X Communications

Experimental Characterization of a Helical Antenna Integrated in the Rear of a Vehicle for C-V2X Communications

Application of Artificial Neural Network Base Enhanced MLP Model for Scattering Parameter Prediction of Dual-band Helical Antenna

Many design optimization problems have problems that seek fast, efficient and reliable based solutions. In such cases, artificial intelligence-based modeling is used to solve costly and complex problems. This study is based on the modeling of a multiband helical antenna using the Latin hypercube sampling (LHS) method using a reduced data enhanced multilayer perceptron (eMLP). The proposed helical antenna is dual-band and has resonance frequencies of 2.4 GHz and 2.75 GHz. The enhanced structure of the artificial neural network (ANN) was tested using 4 different training algorithms and a maximum of 10 different MLP architectures to determine the most suitable model in a simple and quick way. Then, performance comparison with other ANN networks was made to confirm the success of the model. Considering the high cost of antenna simulations, it is clear that the proposed model will save a lot of time. In addition, thanks to the selected sampling model, a wide range of modeling can be done with minimum data. When the target and prediction data are compared, it is seen that these data overlap to a large extent. As a result of the study, it was seen that the ANN modeling and the 125 samples used, were as accurate as an electromagnetic (EM) simulator for other input parameters in a wide range selected.

Revolutionizing Connectivity: The Breakthrough of Batteryless Mouse Using Magnetic Resonant Coupling for Communication Devices

With the rapid development of electronic technology and information technology, personal computer has gradually become the public's office or entertainment tools, which also makes the computer mouse a widely used tool. However, most computer mouse on the market today come with batteries. In this context, it is necessary to design a batteryless mouse that without using power supply such as battery. In view of such demand, on the basic of theoretical analysis, this paper summarizes and designs a classical wireless transmission structure – magnetic resonant coupling and antenna that used to transmit and received power for communication devices. In order to understand the operation of wireless power transmission technology, the paper analysed antenna construction and wireless power transmission technology. The basic design parameters of the axial mode helical antenna structure are also explained. Finally, by using CST STUDIO software, axial mode helical antenna with gain of 6.45 dBi was obtained. The system's output voltage is successfully simulated at 1.516 V that can powered up the computer mouse.

Real-time 14N NQR-based sodium nitrite analysis in a noisy field

Noise and Radio-frequency interference or RFI causes a significant restriction on the Free induction Decay or FID signal detection of the Nuclear Quadrupole Resonance procedure. Therefore, using this method in non-isolated environments such as industry and ports requires extraordinary measures. For this purpose, noise reduction algorithms and increasing signal-to-noise-and-interference ratio or SNIR have been used. In this research, sodium nitrite has been used as a sample and algorithms have been tested in a non-isolated environment. The resonant frequencies for the 150 g of test sample were measured at 303 K at about 1 MHz and 3.4 MHz. The main novelty in this study was, (1) using two types of antennas in the receiver to improve adaptive noise and interference cancellation, (2) using a separate helical antenna in the transmitter to eliminate the duplexer, (3) estimating the noise before sending the pulse to calculate the weighting factors and reduce the noise by adaptive noise cancellation, (3) reject the interference by blanking algorithm, (4) pulse integration in the frequency domain to increase the SNR, and (5) increasing the detection speed by new pulse integration technique. By interference rejection and noise cancellation, the SNIR is improved to 9.24 dB at 1 MHz and to 7.28 dB at 3.4 MHz, and by pulse integration 44.8 dB FID signal amplification is achieved, and the FID signals are detected at 1.057 MHz and 3.402 MHz at room temperature.

RF design of helical long-wire traveling wave antenna for helicon current drive in KSTAR

This paper presents the development, fabrication, and implementation of a state-of-the-art helical long-wire traveling wave antenna (LW-TWA) for the Korea Superconducting Tokamak Advanced Research (KSTAR) helicon wave current drive (HCD). A multi-stage design approach has been employed incorporating schematic and simplified radio frequency (RF) modeling, to fulfill critical antenna performance criteria, such as parallel refractive index, while maintaining low electric field properties and load resilience. The advanced design includes a Faraday shield and a structurally rigid support for mechanical stability and minimal RF performance distortion. The sophisticated design and megawatt (MW)-class RF power handling capability of the LW-TWA hold the potential to improve HCD performance in KSTAR plasma.

A Four-Arm Electrically Small Omnidirectional CP Helical Antenna and Its Expansion as a Compact and Highly Efficient Dual-CP Array

A Four-Arm Electrically Small Omnidirectional CP Helical Antenna and Its Expansion as a Compact and Highly Efficient Dual-CP Array

Design of Normal Mode Helical Antenna for Seawater Application

To overcome the substantial propagation loss in the ocean, a low frequency band should be chosen when contemplating radio wave communication.Then, the antenna used at the portable radio equipment should be very small compare to the wavelength. For the miniaturized antenna, the normal mode helical antenna(NMHA) is suitable because of achieving high efficiency. In this paper, design method of NMHA in the seawater condition (r=81, =4) is explained. The frequency bands of 100MHz and 15MHz are selected. The self-resonant structures are determined based on the theoretical equation. Electrical characteristics such as resonant frequency, input impedance, VWSR and antenna efficiency are obtained through simulation by FEKO simulator. Electromagnetic simulation model is formed by taking into account the practical experimental condition. At 100MHz and 15MHz, resonances are ensured for antenna diameter lengths of 6.83 cm and 12.2 cm respectively. Input resistance of 27.15and 94.14, antenna efficiencies of -14.88dB and -26.27dB are achieved at 100MHz and 15MHz respectively.

A frequency-adjustable helical antenna using shape memory alloy

There is a need to develop low-cost and compact frequency reconfigurable antennas with continuous frequency tuning capability. Existing approaches rely on dedicated electrical, mechanical, or MEMS-based approaches to reconfigure the antenna, which requires extra components and fabrication steps. In this paper, we propose a physics-based approach to realize tunable helical antennas based on a shape memory alloy (SMA). By utilizing the temperature-induced irreversible mechanical deformation of the SMA, the temperature-controlled antenna can continuously change its resonant frequency and lock the state when the desired frequency response is achieved. The height of the helical antenna changes in response to applied temperatures. No additional circuitry or mechanical modules are required for the reconfiguration of the antenna geometry. The fabricated helical antenna can shift resonant frequency between 150 and 195 MHz with a tuning sensitivity of 284 kHz/°C.

Design and analyses of shipborne multifunctional Automatic Identification System (AIS) antenna

ABSTRACT This paper is introducing analyses of new design of the automatic identification system (AIS) ships antenna that will serve for both VHF-band radio and satellite tracking and identification system for maritime applications. The current AIS network is an automatic tracking system used by ships of vessel traffic service for identification and location of vessels by electronically exchanging data between nearby ships and on-shore base station. In the AIS system for the electronic data exchange, the very high frequency (VHF) range is used. Utilizing of the VHF range makes the AIS as short-range communication, identification and collision avoidance system between AIS equipped ships and base station is possible in the antennas line-of-sight . In order to widen the range of the AIS from short range up to long or global range, AIS communication should be used via a satellite. In order to provide communication via satellite as well should be designed multifunctional antenna for both radio AIS (R-AIS) and satellite AIS (S-AIS) communication antenna. The analyses and design of a new multifunctional antenna, calculation and development, including implementation and testing of helical VHF antenna for R-AIS and S-AIS equipment are discussed.

A Compact Axial-Mode Helical Antenna Based on Spoof Surface Plasmon Polaritons

A compact axial-mode helical antenna (AMHA) is presented based on spoof surface plasmon polaritons (SSPPs). The proposed antenna consists of an SSPP waveguide, a matching metal strip, and a reflective metal ground. To achieve miniaturization and good circular polarization (CP) performance, an SSPP waveguide formed by a periodically slotted metal strip wound around a uniform foam cylinder surface is designed as the radiation part of AMHA. Compared with the traditional AMHA using metallic strip line, the SSPP AMHA can reduce the length of metal strip by 20%, while the physical aperture, height, and volume are reduced by 36%, 20%, and 49%, respectively. Experimental results demonstrate that the antenna has good radiation performance in the operation frequency from 3.3 to 4.7 GHz with a gain of 9.6 dBic at the central frequency. In addition, the size of the proposed SSPP AMHA can be further significant reduced if the foam rod in the center of helix is replaced by a high-permittivity dielectric rod. The proposed SSPP AMHA has the advantages of compact size and good CP radiation performance, which may find potential applications in radar and wireless communication systems.

Microwave ion source with dual helical antenna for diagnostics neutral beam of ALBORZ tokamak

An efficient ion source of the diagnostic neutral beam injection (DNBI) is designed and simulated for Alborz Tokamak, based on the microwave plasma source. The diagnostic neutral beam is designed for use in some diagnostics system such as charge-exchange recombination spectroscopy (CXRS), Rutherford Scattering (RS), and Motional Stark Effect (MSE) of Alborz Tokamak. In this work, a new helical antenna is designed and simulated for a microwave plasma source, to reach a plasma density of order8.23×1017m−3. The microwave plasma source is employed by the high-efficient ion beam accelerator. In this simulation, three-electrodes in different potentials of 20 kV, −2 kV, and grounded respectively, are used as extraction system of the ion beam source. According to our design, nine apertures grids are considered for the accelerator system. The simulation results show that, the system can extract an ion beam with energy and current of 20 keV and 60 mA respectively. The extracted ion beam consists of nine beamlets, where the beam waist and the current of each of them are calculated about 3 mm and 6.5 mA, respectively. The results of this work indicate that the ion beam with minimum divergence angle of 32 mrad can be generated by the proposed ion beam source.

A novel helical antenna for high-power design in X-band

This paper describes a novel helical antenna for high-power design in X-band. Based on the advantages of miniaturization, high efficiency, and low-profile from helical antenna, firstly, by optimizing the primary parameters, the helical antenna obtains a significant axial ratio bandwidth and operational bandwidth in X-band. Then in array antenna design, metal frames are introduced to decrease the mutual coupling effects, reducing the lower-impedance bandwidth decrease from 9.77 GHz to 8.08 GHz. Meanwhile, to further realize high-power design, a novel curved feed structure is employed to boost the power capacity increase from 31.1KW to 43.8KW. The measured results show that the proposed helical antenna has an operating bandwidth across X-band (reflection coefficient < −10 dB), and the max power capacity of the antenna finally ascends to 43.8 kW.

Influence of Antenna Element Position Deviation on Radiation Performance of Helical Antenna Array

The electrical performance of the feed array is degraded because of the position deviation of the array elements caused by manufacturing and processing, which cannot meet the high performance feeding requirements of large feed arrays. In this paper, a radiation field model of the helical antenna array considering the position deviation of array elements is proposed to investigate the influence law of position deviation on the electrical performance of the feed array. With the established model, the rectangular planar array and the circular array of the helical antenna with a radiating cup are discussed and the relationship between electrical performance index and position deviation is established by numerical analysis and curve fitting method. The research results show that the position deviation of the antenna array elements will lead to the rise of the sidelobe level, the deviation of the beam pointing, and the increase of the return loss. The valuable simulation results provided by this work can be used in antenna engineering, guiding antenna designers to set optimal parameters when fabricating antennae.

Analysis of gadolinium oxide using microwave-enhanced fiber-coupled micro-laser-induced breakdown spectroscopy

We report on the analysis of pure gadolinium oxide (Gd2O3) and its detection when mixed in surrogate nuclear debris using microwave-enhanced fiber-coupled micro-laser-induced breakdown spectroscopy (MWE-FC-MLIBS). The target application is remote analysis of nuclear debris containing uranium (U) inside the Fukushima Daiichi Nuclear Power Station. The surrogate nuclear debris used in this study contained gadolinium (Gd), cerium (Ce), zirconium (Zr), and iron (Fe). Ce is a surrogate for U, and Gd2O3 is an excellent hazard index because it is incorporated into some fuel rods. Gd detection is essential for assessing debris prior to the retrieval process. Surrogate debris was ablated by an 849 ps 1064 nm micro-laser under atmospheric pressure conditions while a helical antenna propagated 2.45 GHz 1.0 kW microwaves for 1.0 ms into the laser ablation, which was then characterized by a high-speed camera and high-resolution spectrometers. The results showed that microwave-induced plasma expansion led to enhanced emission signals of Gd I, Zr I, Fe I, Ce I, and Ce II. No self-absorption of Gd emissions was evident from the detection limit calibration graphs. Moreover, microwave irradiation decreased the standard deviations of the Gd and Ce emissions and lowered the Gd detection limit by 60%.

A compact channel patch antenna with reconfigurable circularly polarized pattern for mobile satellite communications

A compact dual-band circularly polarized antenna with a characteristic of pattern reconfiguration is proposed for S-band satellite handsets. The antenna works as a patch antenna in a channel shape with no ground beneath reaching an overall size of 0.55λ × 0.14λ × 0.1λ. The dual-band performance is realized through multi-branch slots of the patch. The antenna mainly consists of a channel metal patch, a channel dielectric, and a simple feeding network. The overall shape of slot can be changed by the PIN diode on the patch to adjust the surface current direction, which in turn achieves 180° switching of the left-hand circularly polarized radiation beam direction. In addition, by combining the quadrifilar helical antenna, which is switchable in the end-fire beam direction, the designed antenna can realize the switching of four main beam directions to achieve 360° 3D spatial coverage. The proposed antenna is fabricated and measured to verify the proposed design. The test results show that the designed antenna obtains circularly polarized radiating characteristics in S-band with the center frequency of 1.98 GHz and 2.2 GHz, and the test results and simulation results are basically consistent, which indicates the superior performance of the designed antenna.

A hemispherical helical water antenna array for directional high-gain radiation

This letter proposed a water antenna with a novel shape of a hemispherical helix made of pure water. A plastic water pipe is bent into a hemispherical helix and filled with water to form the helical arm of the antenna. The water arm acts as a director, which enables the antenna to obtain wide-angle radiation characteristic in the axial direction with a beam width of 95.5°. The impedance bandwidth of the antenna (S11 < −10 dB) is 1.30–1.89 GHz. Based on this antenna, a four-element antenna array is also designed. A quasi-Butler matrix is used to feed this antenna array to achieve a reconfigurable pattern. The antenna array can achieve directional high-gain radiation in five directions, covering a total range of 66°. The maximum gain of the array in the effective frequency band can reach 13.8 dBi.