Wire Antenna Research Articles

A Configurable Multiport Wire Antenna for Wideband Beamforming and Beam Scanning

A Configurable Multiport Wire Antenna for Wideband Beamforming and Beam Scanning

Doppler sensitivity and resonant tuning of Rydberg atom-based antennas

Radio frequency antennas based on Rydberg atom vapor cells can in principle reach sensitivities beyond those of any conventional wire antenna, especially at lower frequencies where very long wires are needed to accommodate the increasing wavelength. They also have other desirable features such as consisting of nonmetallic, hence lower profile, elements. This paper presents a detailed theoretical investigation of Rydberg antenna sensitivity, elucidating parameter regimes that could cumulatively lead to a sensitivity increase 2–3 orders of magnitude beyond that of currently tested configurations. The key insight is to optimally combine the advantages of two well-studied approaches: (i) three laser ‘2D star configuration’ setups that, when enhanced with increased laser power, to some degree compensate for atom motion-induced Doppler broadening, and (ii) resonant coupling between a pair of near-degenerate Rydberg levels, tuned via a local oscillator to the incident signal of interest. The advantage of the star setup is subtle because it only restores the overall sensitivity to the expected Doppler-limited value, compensating for additional significant off-resonance reductions where differently moving atom sub-populations destructively interfere with each other in the net signal. An additional unique advantage of local oscillator tuning is that it leads to vastly narrower line widths, as low as ∼10 kHz set by the intrinsic Rydberg state lifetimes, rather than the typical ∼10 MHz scale set by the core state lifetimes. Intuitively, with this setup the two Rydberg states may be tuned to act as an independent high-q cavity, a point of view supported by a study of the frequency-dependence of the antenna resonant response. There are a number of practical experimental advances, especially larger ∼1 cm laser beam widths, required to suppress various extrinsic line broadening effects and to fully exploit this ‘Rydberg superheterodyne’ response.

Fractal Interpolation Function based Thin Wire Antennas

This paper presents an approach for the design of wire antennas based on fractal interpolation functions (FIFs). The interpolation points and the contraction factors of the FIFs are chosen as free parameters to modify the antenna geometry. The proposed structures’ gain and radiation pattern can be optimized using FIF parameters. Producible prefractal antennas obtained in the intermediate iterations of fractal generation have compact sizes compared to classical counterparts. The error in prefractal geometry and the original fractal is bounded, and can be determined in terms of the finest producible detail’s dimensions. The emerging structures have multiband behavior due to their self-similar and symmetric nature. To illustrate the approach, we have provided finite element based simulations for several prefractal antennas. |S11|, the gain, the radiation efficiency, the radiation patterns, and feed point impedances for the demonstrated antennas are calculated numerically. The results indicate that produced antennas can be used in applications that require limited mechanical size, multiple operating bands, and controlled radiation patterns.

The extended resonant modal theory and its applications

AbstractThe authors extend the resonant modal theory (RMT) developed previously for a metal object to an arbitrary source region consisting of metals, dielectrics, or a combination of both. The influences of dielectrics on the fields are replaced by equivalent volume sources through the use of the compensation theorem in electromagnetic theory. The resonant frequencies can be determined by finding the roots of the determinant of the matrix resulted from the discretisation of the real homogeneous volume–surface integral equation derived from the requirement that the difference of stored field energies in the source region vanishes. As applications of the extended RMT, three examples have been investigated. The first example is a dielectric resonator antenna and is designed by exciting the first resonant mode of the composite structure in which the dielectric cylinder is combined with a conformal metallic strip. The second example is a dual‐band dielectric‐coated metallic wire antenna. The third example studies the resonant modes of a rectangular patch antenna.

Analytical Expressions for Spherical Wire Antenna Quality Factor Demonstrating Exact Agreement Between Circuit-Based and Field Integration Techniques

Analytical Expressions for Spherical Wire Antenna Quality Factor Demonstrating Exact Agreement Between Circuit-Based and Field Integration Techniques

Wire antenna with skew planar wheel structure for generating high‐purity OAM beam

AbstractThis paper presents the generation of an orbital angular momentum (OAM) wave using a wire antenna with a skew planar wheel structure at 5.8 GHz. The wire antenna consists of four arms, each of which behaves like a left‐handed circularly polarized antenna. The orientation and rotation of each arm are adjusted to obtain the desired phase shift, resulting in the generation of an OAM wave. The proposed design is fabricated and tested, and the results demonstrate that the OAM beam produced has high mode purity, with a peak gain of 2.8 dBi, divergence angle of , and high azimuthal symmetry. Both simulated and measured results confirm the effectiveness of the proposed wire antenna in generating an OAM wave. The proposed wire antenna has a wide range of potential applications, including communication systems, remote sensing, and radar imaging. In particular, the azimuthal symmetry of the OAM beam makes it particularly suitable for unmanned aerial vehicle applications.

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..

Intracavitary Applicator for Sequential Delivery of Localized Hyperthermia Through Non-Metallic Uterine Tandem.

In this work, we report the design and demonstration of a flexible coaxial wire antenna with a low profile flexible choke for delivering localized hyperthermia (HT) treatment to the cervix through a custom designed uterine tandem applicator. Resistive and magnetic materials were investigated for determining the flexible choke design suited for intracavitary HT treatment at 915 MHz. Measurements of the intracavitary antenna with the flexible choke in tissue mimicking phantom and ex-vivo bovine muscle through the non-metallic uterine tandem prototype confirm the ability to deliver localized HT to the cervix at 915 MHz and 50 mm insertion depth.

Circuit Model for Nth-Order Filtering Wire Antenna, Parameter Extraction, and Radiation Prediction

This article proposes a general circuit model for a thin wire antenna and a generalized approach to design an <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$N$</tex-math> </inline-formula> th-order parallel coupled wire antenna with its companion circuit model. Frequency-variant <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$K$</tex-math> </inline-formula> -inverters are involved in the new equivalent circuit to describe the frequency-variant radiation effect of the antenna. The design procedure starts with an initial prototype developed from a synthesized arrow coupling matrix, and then, its companion circuit is constructed accordingly. All the circuit parameters associated with the prototype can be extracted from EM models using space mapping technology. Iterative tuning is employed in the EM and circuit model, such that the final response satisfies the given specifications. An analytic method based on the circuit model is proposed to predict the radiation performance of the antenna. It is the first time ever that this type of filtering antenna has been designed and predicted quantitatively by using its circuit model, and the tuning of the antenna structure can also be guided by its circuit model. The proposed method offers a deterministic way for optimally designing an arbitrary-order filtering wire antenna with proper frequency characteristics.

Theoretical Study and Systematic Design of Multiport Wire Antenna

This work presents a systematic study of multi-port wire antennas (MPWA) as a step toward reconfigurable radiation apertures, an essential component in modern wireless systems. We predict the surface current distribution (SCD) of the multi-port structure and derive a closed-form relation for the radiation pattern of the aperture as a function of its input port excitations. Based on this, we present a design procedure for optimal selection of port locations and their respective input excitations with a desired radiation pattern in mind. Finally, we develop a computationally efficient method to derive the impedance matrix of the multi-port aperture all without the need for full-wave simulation. As an example, we use this method to design a 15-port mm-wave antenna. We demonstrate that for a selected aperture size and port locations and only by adjusting the phases and amplitudes of excitation, we can reconfigure the MPWA to synthesize a desired beam at any frequency within the 20-40GHz range. There is good agreement between results predicted by this method compared to those from EM-based simulations, enabling an efficient and scalable approach for designing multi-port radiators.

Dark band artifact in transcranial MR-guided focused ultrasound: Mechanism and mitigation with passive crossed wire antennas

Current FDA-approved transcranial MR-guided focused ultrasound (tcMRgFUS) transducers cause a curved dark band in 3 T brain images that runs through midbrain targets of ablative treatments for essential tremor and other applications, and signal is reduced by at least 25% elsewhere in the brain. This limits the set of scans that can be performed to guide and assess the effects of treatment. An electromagnetic simulation study was performed to elucidate the mechanisms causing the dark band. Based on the results, a pair of passive antennas in a “propeller-beanie” configuration were designed to manipulate the reflected waves to avoid signal cancellation within the brain. The antennas were optimized and validated with in-vivo experiments and hydrophone measurements. The simulation study revealed that the dark band is caused by RF waves reflected from the transducer's ground plane, which cancel with incoming waves from the scanner's body coil. The passive antennas shifted the dark band out of the brain and increased transmit efficiency in the center of brain 2.3 times while improving field homogeneity by 50%. They also increased receive sensitivity and SNR in anatomic and temperature imaging. They caused no detectable distortion in hydrophone-measured focal pressure profiles. The conductive ground planes and coupling media used in tcMRgFUS and other piezoelectric FUS transducers interact with a 3 T scanner's RF fields to reduce transmit efficiency and SNR. For tcMRgFUS scenario, “propeller beanie” passive reflecting antennas alleviated these effects. This could make a broader set of imaging sequences available to guide tcMRgFUS treatment.

Remote microwave heating and ignition with an embedded receiving antenna within nanocomposites

This study demonstrates the use of a receiving antenna within a material to transmit microwave energy resulting in dielectric heating and ignition in a direct writing process. The wire antennas themselves do not heat, but rather the induced electric field results in dielectric heating of the sample, and with sufficient electric field strength, triggers ignition. With different length of embedded receiving antenna, local hot spots were generated at the ends of the receiving antenna as imaged with an IR camera. Simulation of a monopole source and receiving antennas, shows a spatial correspondence of the calculated electric field and the measured hot spots. We also demonstrate that receiving antennas can be incorporated to trigger ignition at desired locations, with multiple ignition points from which flame propagations can be induced. This study provides a new way to design and remote control the location of the hot spots and ignition.

Development and Research of a Medium Vertical Dipole Electromagnetic Pulse Simulator

In this paper, the design of a self-developed EMP simulator with a 5 m height and an inverted conducting mono-cone antenna with a cone half-angle of 32° is introduced. The experimental region of the simulator is a circular area of 25 m in diameter around the cone vertex. Two feeding modes, feed-in over the ground and feed-in under the ground, are realized by two different high-voltage pulse sources. It can be concluded through radiation field testing that the radiation field waveform generated by the simulator has a rise time of 2–3 ns and a half-width of about 25 ns, meeting the specifications of the EMP experimental waveform in the IEC61000-2-9 standard. Meanwhile, the differences between the engineering implementation of the simulator and its ideal structure during the design process can lead to some distortion issues in the antenna radiation characteristics and the electromagnetic radiation field it generates. The radiation field waveform and the distribution of the EMP field generated by the simulator under different feeding methods, antenna wire quantities, antenna end processing methods, and different antenna resistive loading were studied, and the changes in the radiation field waveform and field distribution with different angles and distances of the monitoring point were analyzed. Based on the measurement results, the radiation characteristics of the antenna and the factors that affect the waveform of the field were studied and analyzed. Through the aforementioned work, a comprehensive understanding of the performance, radiation characteristics, and engineering factors affecting the electromagnetic environment generated by the simulator has been obtained. On this basis, the parameters of the antenna wire quantity, antenna end processing method, and test point position of the designed simulator were reconfirmed and optimized. In summary, this work has important reference significance for mastering the development technology of such simulators, understanding their antenna radiation characteristics, and conducting EMP-related assessments and effect experiments in the future.

Mathematical Model of the Unbalanced Monopole Feed. Part 2. Determination of Complex Capacitance of Normally Open Wire Antennas, Small with Respect to the Wavelength

A method for calculating the complex capacitance of small with respect to the wavelength, normally open antennas is proposed. Analytical expressions for determination of mutual potential coefficient of any two arbitrarily arranged linear conductors are obtained. The proposed technique can be useful in assessing the losses of normally open wire antennas placed in close proximity to the semiconductor surface, as well as in determination of their input resistance.

Solution of integral equations of linear antenna theory by finite element method

The aim of the work is to construct a computational scheme of the finite element method in relation to integral equations describing current distributions in thin wire antennas. In particular, for linear antennas of small thickness, the problem can be reduced to the integral Gallen equation. As a research method, preference is given to the finite element method, since it has quite a lot of flexibility in terms of choosing basis functions and selecting a grid of nodes. In addition, this method is a powerful and effective means of solving mathematical physics’ problems, which makes it possible to accurately describe complex curved boundaries of the solution domain and boundary conditions. The paper builds a numerical method for solving the integral Gallen equation using the finite element approach. According to the proposed computational scheme, a software implementation was built and a comparative analysis of the results was carried out. This approach as a whole showed low accuracy, which is probably due to the fact that this problem belongs to the class of incorrect ones and, in general, is due to the issue of determining the limits of applicability of the Gallen equation.

On-Chip Electrostatic Actuation of a Photonic Wire Antenna Embedding Quantum Dots

A photonic wire antenna embedding individual quantum dots (QDs) constitutes a promising platform for both quantum photonics and hybrid nanomechanics. We demonstrate here an integrated device in which on-chip electrodes can apply a static or oscillating bending force to the upper part of the wire. In the static regime, we achieve control over the bending direction and apply at will tensile or compressive mechanical stress on any QD. This results in a blue shift or red shift of their emission, with direct application to the realization of broadly tunable sources of quantum light. As a first illustration of operation in the dynamic regime, we excite the wire fundamental flexural mode and use the QD emission to detect the mechanical vibration. With an estimated operation bandwidth in the GHz range, electrostatic actuation opens appealing perspectives for the exploration of QD-nanowire hybrid mechanics with high-frequency vibrational modes.

Study of Helical Antenna Endowing Short Wire Length and Compact Structure for High-Frequency Operations and Its Exclusive Manufacturing Process

In this paper a study of a helical antenna resonating at high-frequency (HF) band with a very compact structure is reported. The designed antenna's S11 parameter magnitude change with frequency was calculated for different geometrical parameters. For each case, first, only a single parameter was changed. Then for a fair comparison, multiple parameters were changed simultaneously while the total wire length was set to be constant. Also, shifts in resonance frequencies and variations in -10 dB bandwidths were investigated. Our results show that resonance behaviour changes distinctively with the geometrical parameters and it allows shortening of the antenna wire length. For the designed antenna, the resonances shift to lower frequencies and -10 dB bandwidths around the resonances decrease as the winding wire thickness, number of turns, and turn radius increase. Whereas as the turn spacing increases the resonances shift to higher frequencies and -10 dB bandwidths widen, although the total wire length of the antenna increases. To verify the simulation results, the designed antenna was fabricated with an exclusive manufacturing process and characterized. The measurement results are in good agreement with the simulation results. It demonstrates the feasibility of the proposed manufacturing technique, which is new in the literature and enables accurate and rigid antenna fabrication with simple and low-cost steps.

Wire-Grid and Sparse MoM Antennas: Past Evolution, Present Implementation, and Future Possibilities

Since the end of the 19th century, radioelectronic devices (REDs) have actively penetrated into all modern community spheres. Achievements in the fields of radio engineering and electronics, as well as computing, information, telecommunications, and other technologies, have greatly contributed to this. The main elements of REDs are antennas and microwave devices. For example, linear (wire) antennas are the basis of long-distance communication agency networks of various law enforcement agencies and departments. The manufacturing of REDs requires the regular and rapid appearance of more and more advanced types with minimal costs. At the same time, the design complexity of REDs and the tightening of EMC requirements caused by the growth of upper frequencies of useful and interfering signals, the mounting density, as well as the capabilities of generators of intentional electromagnetic impacts, together with the need to take into account inter-element, inter-unit, and inter-system interference, require more and more accurate designs of REDs. However, this becomes impossible without computer modeling, which saves the time and financial resources required for their development, as well as to evaluate the correctness of the proposed technical solutions. During the design process, as a rule, a multivariate analysis or optimization of the product is performed. In this case, methods of computational electrodynamics (one of which is the method of moments) are used. They are based on the replacement of continuous functions with their discrete analogues (construction of a grid), which reduces the problem to the solution of a system of linear algebraic equations (SLAE). The problem’s complexity depends on the complexity of the SLAE solution, which is determined by its order (which in turn is determined by the complexity of the simulated object and its surrounding area) and by the number of the required SLAE solutions for each problem (determined by the upper frequency of the signal, the number, and range of the optimized parameters). This dramatically increases the computational cost, which becomes the main constraint for the optimal design. Therefore, reducing the computational cost for the analysis and optimization of RED elements (in particular, linear antennas) is an important scientific problem. Meanwhile, finding new antenna structures that meet all the desired features (low price, required characteristics, manufacturable design with small dimensions and windage, etc.) is no less important today. One of the promise solutions for these problems is using a wire grid and sparse antennas for modeling and constructing antennas. Since the last century, a lot of research has been performed on them. The aim of this paper is to review their history and the main related aspects such as computational, acceleration, and optimization used methods, the fields of their application, and their evolution to this moment. In addition, this paper provides a possible future implementation of wire-grid and sparse antennas from the authors’ point of view by presenting a new method that is under research to obtain effective wire sparse antennas.

Typical Constructs in Unveiling the Horizontal Wire Antenna

Typical Constructs in Unveiling the Horizontal Wire Antenna

COMPUTATIONAL FEATURES OF CALCULAT-ING EXTENDED CONDUCTOR ANTENNAS BASED ON THE INTEGRAL EQUATIONS METHOD

The numerical solution of integral equations or a system of integral equations (for a system of conductors) consists in their discretization and reduction to a system of linear algebraic equations for the desired function. For discretization, it is possible to use projection methods, for example, the Galerkin method or the collocation method. A system of linear algebraic equations for the class of problems under consideration is characterized by a complete (filled) complex matrix. For conductor antenna structures that are quite arbitrary in geometry and size, systems of linear algebraic equations turn out to be of a high order, and special computational algorithms are required to solve them. The purpose of the work is to study adequate mathematical models for wire antennas with a subsequent description of uniform numerical algorithms based on methods of sampling and approximation of antenna current. With this method, the error in solving integral equations is determined by the error in calculating the elements of the matrix of a system of linear algebraic equations for a given piecewise polynomial approximation of the solution at step h. If the quadrature formula for numerical integration is chosen, then there are two ways to reduce the solution error. An increase in the number of collocation points leads to a rapid increase in the volume of calculations and, consequently, to a rapid increase in the amount of occupied computer memory. Therefore, the question arises of choosing the most profitable method of piecewise polynomial interpolation and discretization step h from the point of view of using computer resources, ensuring an acceptable number of solutions.