Plasma Antenna Research Articles

Design and development of plasma antenna for wi-fi application

The term plasma is often referred to as the fourth state of matter. When sufficient ionized, plasma can be a conductor element. Plasma antenna is a type of radio antenna that represents the use of ionized gas as a conducting medium instead of metal conductors. The main objective in this research is to design plasma antenna at 2.4 GHz by using commercial fluorescent tube. In this work the commercial fluorescent lamp was chosen because it was low cost to produce plasma element. The plasma antenna in this research was made from fluorescent lamp that functioned as a radiating element with target frequency at 2.4 GHz for Wi-Fi application. The commercial fluorescent lamp consisted of argon gas and mercury vapor with a diameter of 28 mm and a length 589.8 mm. The result showed that a fluorescent tube, can be used to work as a plasma antenna for Wi-Fi application.

ANTENNAS WITH STEERABLE DIRECTIONAL PATTERNS

The actual methods and devices for correction and control of the antenna pattern of metal rod and loop, as well as plasma and electron beam reconfigurable antennas are analyzed. It is suggested to solve the problems of efficient correction and control of the directional patterns of metal antennas through changing their design and inserting lumped reactive loads and switches in the antenna arms. Also, the problems like these are suggested to be solved via construction of reconfigurable antennas on the basis of cold plasma or moving electron flows with inserted switches of the information signals and electric power. Calculation results are presented for steerable Z-shaped and rhombic antennas with lumped loads and switches inserted in the radiating conductors. The gain and voltage standing wave ratio of the antennas with correctable and controllable directional patterns are analyzed. In is noted that, in contrast to the metal reconfigurable antennas and antenna arrays, the plasma and electron-beam antennas suggest more capabilities to control the directional pattern and other electrical parameters through creating the so-called conducting paths in the structures. In this case the deactivated conducting paths have no longer any effect on the antenna operation. It is suggested to beforehand plan and program activation and deactivation of the necessary conducting paths in the specified periods of time in order to obtain the required directional patterns. Results are presented of calculating the directional patterns and other electrical parameters of a metal collinear antenna array of the Franklin-Marconi type and a plasma eight-element reconfigurable antenna. A version of a novel electron-beam reconfigurable antenna is presented. The results of the study are given in the form of tables and graphs. It is noted that the metal, plasma and electron-beam reconfigurable antennas are promising for application in radio systems including ground-based, marine and aerospace telecommunication and radar systems.

THE PLASMA ANTENNA WITH AZIMUTHAL-ASYMMETRICAL TRAVELING WAVES OF CURRENT

In paper the plasma antenna with azimuthally asymmetrical traveling waves operating at a harmonic with an azimuth number m = 1 is theoretically and numerically investigated. Besides the collisions of electrons with atoms are taken into account. Plasma is assumed to be cold and isotropic. The method of the dispersion equation is used. The propagation constant and the attenuation coefficient of the traveling wave can be obtained from the real and imaginary parts of the solution of this equation, respectively. In order to find the directional patterns, the delayed potentials in the far zone are calculated. The directional patterns depend strongly on the slowing of waves in the antenna. The dependences of the slowing of the wave on the plasma density are obtained. The dependence of the pattern on the plasma density, the geometrical parameters of the plasma cylinder and the frequency of electron-atom collisions is investigated. The minimum values of the plasma density, at which the normalized antenna patterns are highly directional and have a main lobe located at a zero angle to the antenna axis, are obtained. Advantages of the antenna operating at the harmonic with m = 1, as compared to the antenna working on an azimuthally-symmetrical wave, are shown: the working plasma density of such an antenna is much lower; the radiation is in a strictly axial direction; a small level of the side lobes of the directional pattern. The antenna pattern is less dependent on the electron-atom collisions. It is also shown that, by dispersion properties, a plasma antenna with m = 1 is closer to a metallic antenna than an antenna with m = 0.

A Study of the Characteristics of a Deformable Antenna Based on Gas Discharge

This paper presents an introduction to a deformable plasma antenna excited by an alternating current power supply at a frequency of 12 kHz. The deformable discharge tube could be transformed into many types of shapes, such as a monopole, U-shape, loop, helix, or plane, by means of a simple mounting and rotating system. The characteristics of the antenna were studied for various discharge parameters and antenna shapes. Experimental results demonstrate that the antenna characteristics, such as impedance, radiation pattern, gain, and polarization, can be simply controlled by varying the discharge parameters and antenna shapes. Compared with a conventional plasma antenna made of hard materials, the reconfiguration scope of the deformable plasma antenna is considerably broader. Moreover, the antenna shape can be modified in a manner that is both flexible and easily implemented.

The Influence of the Motion of a Strongly Magnetized Plasma on Radiation from a Traveling-Wave Antenna

We consider the problem of radiation from a traveling-wave antenna in a warm electron plasma which moves along a strong magnetic field at a constant velocity. To describe the electromagnetic properties of the plasma, we use the diagonal tensor of dielectric permittivity, which is calculated for a magnetized plasma with the Maxwellian electron velocity distribution allowing for collisions of electrons with neutral molecules. The dispersion relation is analyzed numerically, and expressions for the field amplitudes in the wave zone are obtained. The radiation resistance of the antenna is calculated. It is shown that as the phase velocity of the traveling current wave in the antenna approaches the average velocity of the plasma motion, the radiation field decreases exponentially with distance from the source as a result of the efficient transfer of the wave energy to the plasma electrons due to collisionless interaction.

Finite-Difference Time Domain Techniques Applied to Electromagnetic Wave Interactions with Inhomogeneous Plasma Structures

Motivated by the emerging field of plasma antennas, electromagnetic wave propagation in and scattering by inhomogeneous plasma structures are studied through finite-difference time domain (FDTD) techniques. These techniques have been widely used in the past to study propagation near or through the ionosphere, and their extension to plasma devices such as antenna elements is a natural development. Simulation results in this work are validated with comparisons to solutions obtained by eigenfunction expansion techniques well supported by the literature and are shown to have an excellent agreement. The advantages of using FDTD simulations for this type of investigation are also outlined; in particular, FDTD simulations allow for field solutions to be developed at lower computational cost and greater resolution than equivalent eigenfunction methods for inhomogeneous plasmas and are applicable to arbitrary plasma properties such as spatially or time-varying inhomogeneities and collision frequencies, as well as allowing transient effects to be studied as the field solutions are obtained in the time domain.

A novel reconfigurable radiating plasma antenna array based on Yagi antenna technology

An electronically controlled plasma reflector antenna array is presented in term of Yagi antenna technology and plasma theory in this paper. The array comprised of a plasma symmetrical dipole in the center and 6 plasma column antennas uniformly around the dipole. When only the active plasma dipole and one of passive columns are energized, they perform like conductive metals capable to radiate radio signal like a two-element plasma Yagi antenna. Pattern reconfigurability of the antenna array can be achieved by sequentially exciting one of 6 plasma columns, and the plasma antenna array also produces better gain through increasing the number of plasma reflectors. Due to the adoption of equal amplitude and phase feeding technology, it greatly reduces the technical difficulty of the implementation of pattern reconfigurability. On the other hand, if all of plasma columns are off, there is only minor reflection from dielectric tubes, and hence, the plasma antenna array has stealth performance.

Analytical and Numerical Study of a Gaseous Plasma Dipole in the UHF Frequency Band

Gaseous plasma antennas are appealing in applications in which reconfigurability is desired, because the radiation properties can be changed by tuning the plasma parameters. In this paper, an analytical and numerical analysis of a gaseous plasma dipole that works in the 0.3–3 GHz frequency range is presented; the plasma dipole is comprised of two discharges that are arranged similar to the arms of a center-fed metallic dipole. The analytical approach can provide the short- and open-circuit resonance frequencies of the plasma dipole, which have been proven reconfigurable by adjusting the discharge length and by adjusting the density of the plasma therein. Thanks to the numerical approach, the role of the type and pressure of the neutral gas species, and the magneto-static field on the reflection coefficient, and the gain function has been investigated. Finally, a feasibility study of an actual plasma dipole is presented; specifically, the choice of coupling the signal to be radiated by means of electrodes immersed in the plasma is a key to achieve radiation efficiency close to 90%.

Long-lived laser-induced arc discharges for energy channeling applications

Laser filamentation offers a promising way for the remote handling of large electrical power in the form of guided arc discharges. We here report that it is possible to increase by several orders of magnitude the lifetime of straight plasma channels from filamentation-guided sparks in atmospheric air. A 30 ms lifetime can be reached using a low-intensity, 100 mA current pulse. Stability of the plasma shape is maintained over such a timescale through a continuous Joule heating from the current. This paves the way for applications based on the generation of straight, long duration plasma channels, like virtual plasma antennas or contactless transfer of electric energy.

Investigation of surface PiN diodes for a novel reconfigurable antenna

In this paper, investigations of surface PiN diodes developed for a reconfigurable plasma antenna have been described. To increase carrier concentration within the surface PiN diodes as much as possible, parameters of the plasma region have been extensively discussed. According to these studies, it has been found that the average carrier concentration within the ‘i’ region has been achieved the level of 1018 cm−3 at forward bias of 2 V. The carrier concentration becomes larger when the length and width of the ‘i’ region are reduced. Furthermore, a novel frequency reconfigurable antenna based on SPiN diodes is presented at Ku-band. The resonance frequencies at 13.71 GHz, 15.17 GHz, and 17.81 GHz have been easily achieved by turning on or off different sections of the antenna. The radiation efficiencies of the antenna are 79.70%, 80.70%, and 81.70%, respectively. Experimental results shown in this paper confirm the usefulness of the PiN diode’s application within a plasma antenna and other semiconductor fields.

Analysis of nested design of plasma antenna based on the azimuthally symmetric surface waves: UHF and SHF bands

In this paper, a plasma antenna nested inside a plasma tube, called the nested model of the plasma antenna, as a suitable candidate to improve the conventional plasma antenna is theoretically investigated in ultra-high frequency (UHF) and super high frequency (SHF) ranges. Using the Fluid-Maxwell equations, the dispersion relations for both the nested model of plasma antenna and single plasma antenna and single plasma antenna are obtained to find their practical, vph≥0.85c, azimuthally symmetric surface modes. The numerical results for the single plasma antenna show that the number of practical modes is very limited in the UHF range, and in the SHF range, the phase velocities of the modes radiating over this range are mostly lower than the speed of light in vacuum. However, the results of the considered nested model indicate that in the UHF range, the number of practical modes greatly increases, and by optimizing the plasma tube parameters, the generated modes can extend over all this range, forming a mode line with the phase velocity very close to the speed of light. On the other hand, in the SHF range, employing the nested model leads to an additional mode line having higher phase velocity (coinciding with the light speed line under the optimum conditions) with respect to that of the single plasma antenna. Using the proposed nested model of the plasma antenna not only leads to clearly significant advances in the single plasma antenna but also is more controllable due to adding the plasma tube parameters.

A Theoretical Description for Elliptical Plasma Antenna Response in Presence of Terahertz Electromagnetic Plane Wave Based on Surface Plasmon Concept

Excitation of THz surface plasmons due to the scattering of transverse magnetic (TM) wave by an elliptical plasma antenna consisting of a metallic rod with dielectric coating is investigated. The incident, transmitted, and scattered electromagnetic waves are expressed in terms of Mathieu and modified Mathieu functions. The geometrical structure and its effect on the scattering cross-section and resulting resonance frequencies are studied and analyzed based on theory of Fabry-Perot resonator. It is shown that the resonance frequency can be varied by changing the geometrical structure and material used between the surfaces of this structure.

Formation of a plasma antenna by an explosive action in the ionosphere

We have studied the radiative characteristics of the explosive action in the atmosphere. It has been shown that even a single explosive action produced simultaneously with a high-frequency (HF) discharge forms an effective plasma antenna. In the absence of an HF discharge, an explosive action with a specific arrangement of point explosions allows the generation of a convergent shockwave of pressure and magnetic field. As a result, a waveguiding disturbance of the background plasma is formed in the convergence region of the shockwave; given the simultaneous excitation of pulsed fields in the near-frontal region, this also leads to the formation of a plasma antenna at high altitudes.

Simulations of a beam-driven plasma antenna in the regime of plasma transparency

In this paper, the theoretically predicted possibility to increase the efficiency of electromagnetic radiation generated by a thin beam-plasma system in the regime of oblique emission, when a plasma column becomes transparent to radiation near the plasma frequency, is investigated using particle-in-cell simulations. If a finite-size plasma column has a longitudinal density modulation, such a system is able to radiate electromagnetic waves as a dipole antenna. This radiation mechanism is based on the conversion of an electron beam-driven potential plasma wave on the periodic perturbation of plasma density. In this case, the frequency of radiated waves appears to be slightly lower than the plasma frequency. That is why their fields enable the penetration into the plasma only to the skin-depth. This case is realized when the period of density modulation coincides with the wavelength of the most unstable beam-driven mode, and the produced radiation escapes from the plasma in the purely transverse direction. In the recent theoretical paper [I. V. Timofeev et al. Phys. Plasmas 23, 083119 (2016)], however, it has been found that the magnetized plasma can be transparent to this radiation at certain emission angles. It means that the beam-to-radiation power conversion can be highly efficient even in a relatively thick plasma since not only boundary layers but also the whole plasma volume can be involved in the generation of electromagnetic waves. Simulations of steady-state beam injection into a pre-modulated plasma channel confirm the existence of this effect and show limits of validity for the simplified theoretical model.

The role of terahertz surface plasmons in the scattering pattern of electromagnetic waves in an unstable elliptical plasma antenna

The scattering phenomenon of plane waves from an unstable elliptical plasma antenna is investigated. The role of surface plasmon excitation in the scattering pattern is studied. In the antenna mentioned above, there is a metallic rod with dielectric cover embedded in a long plasma column with an elliptical cross section. The antenna is considered unstable because of the injection of an electron beam into the plasma layer. The effects of applied accelerating voltage and applied current intensity on the scattering pattern and resonance frequency are investigated. The geometrical structure and its effect on the scattering cross section and creation of new resonance frequency are studied.

A mathematical description for the scattering phenomena of plane wave from elliptical plasma antenna located in oblique static magnetic field

The problem of electromagnetic wave scattering from an elliptical plasma cylinder in the presence of an external oblique magnetic field is investigated. The electromagnetic waves are landed obliquely on the plasma column. Knowing the dielectric permittivity tensor of the plasma column, the electric potential and the electric field inside and outside the plasma column are obtained for the long-wavelength waves. The graphs of the electric field profile and pattern scattering are presented. Also, the dependence of those graphs on the incident angle, the geometrical dimensions of the plasma column and the magnetic field angle are analyzed. The physical justifications based on the theory of Fresnel’s transmission coefficients for describing the graphs, have been presented. Moreover, the effective factors on the shift of the resonance frequency are investigated. Finally, to verify the accuracy of the obtained results, some limiting cases are discussed.

Radiation enhancement mechanism for a cylindrical metallic antenna surrounded by a thin plasma layer

Based on the dispersion equation obtained from Helmholtz equation in the sheath region and plasma layer region, and free space region of the azimuthally symmetric surface wave, the propagation constant properties on the interface of the plasma layer region and free space region, the mode radiation enhancement characteristics in the free space region are studied. The analytical results indicate that the collision effect has an evident influence on the attenuation constant, but the impact on phase constant can be ignored when the wave frequency is equal to the plasma frequency. While the radiation enhancement phenomenon due to a plasma layer is confirmed, both the sheath thickness and plasma layer thickness have a notable effect on the amplitude of the maximum radiation enhancement intensity. These analytic results have an important theoretical guidance value in the optimization of plasma antenna radiation field.

Radiation of a travelling-wave antenna in plasma in the whistler frequency band

The far field, the radiation pattern, and the radiation impedance of a traveling-wave antenna oriented in plasma along the external magnetic field in the resonance region of the whistler frequency band are studied. It is shown how the main characteristics of the antenna depend on its length and the current propagation constant along the antenna wire.

Analysis of modes radiation, transmission, and loss properties for the un-magnetized cylindrical plasma antenna

The phase properties of both azimuthal and non-azimuthal symmetric surface waves are investigated analytically in an un-magnetized cylindrical plasma column based on the transcendental dispersion relation. A novel method of calculating the transmission power and loss power in the plasma column in terms of complex electric conductivity is proposed. Based on the fully calculated dispersion properties and field profiles obtained from the field matching method, it is shown that the electron plasma frequency has an evident influence on dispersion curves for both azimuthal and non-azimuthal symmetric surface waves; the radiation patterns of the m = 0, m = 1, and m = 2 modes have an evident dependence on the wave frequency; and the transmission power and loss power increase evidently when ωpe/ω > 1, while the collision frequency also has a notable influence on the transmission power for all the three modes.

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.