Plasma Antenna Research Articles

Ohmic Resistance Correction for an Inductive Modulator in DC‐Condition Biassed Plasma Antennas, While Modulation the Signal in the VLF Band

In this research, the performance of an inductive modulator during energy injection into a straight rod plasma antenna, activated using a DC electric discharge, has been experimentally investigated. The primary focus of this study is on correcting one of the parameters of the inductive modulator, specifically its ohmic resistance. The variations in the ohmic resistance of the modulator with respect to frequency in the very low frequency (VLF) range, between 100 kHz and 50 MHz, are analyzed. This analysis is conducted under varying pressures within the plasma antenna tube. Additionally, the effect of the modulator’s position, whether near or far from the cathode, on the modified ohmic resistance variations is examined and simulated in this study.

Plasma-activated copper-alkanolamine precursor paste for printed flexible antenna: formulation, mechanism, and performance evaluation

Plasma activation mechanism and antenna application of a printable copper precursor paste were explored, demonstrating its feasibility for use in flexible wireless electronics.

The Problem of Determining the Characteristics of Optical Semiconductors in Plasma Antennas Design and Its Solutions

The Problem of Determining the Characteristics of Optical Semiconductors in Plasma Antennas Design and Its Solutions

Realization of Plasma Antenna using U-Shaped Compact Fluorescent Lamp

Abstract This paper introduces a novel plasma antenna utilizing a U-shaped compact fluorescent lamp (CFL) as the radiating element, excited by an alternating current (AC) supply. Unlike conventional designs, the coupling sleeve in this plasma antenna is positioned beneath the ground plane, reducing unwanted radiation when the plasma is deactivated. Two prototypes were fabricated, varying only in height (35.7 mm and 77 mm). Measurements at 900 MHz revealed significant differences in radiation patterns between ON and OFF states, indicating effective radiation in the ON state. However, at 450 MHz, only the shorter antenna (35.7 mm) exhibited acceptable performance. The results demonstrate that a U-shaped CFL can serve as an efficient plasma antenna, with performance comparable to classical dipole antennas within the tested frequency range.

Multiband and Wider Bandwidth Plasma Antenna Design Using 3D FDTD

ABSTRACTIn this study, the far‐field characteristics of a plasma dielectric resonator antenna are investigated. The internal structure of the antenna is filled with a plasma material. Surface currents are obtained in an imaginary closed area formed at a certain point outside the plasma antenna. Then, the near field‐far field transformation is performed with the FFT method using the surface currents. The field distributions in the far field of the plasma antenna have been evaluated using three‐dimensional FDTD. The system has shown to work in multiband with wider bandwidths.

Effect of the method of excitation of the plasma antenna on the spectral characteristics of the radiated signal

The radiation of signal by the plasma asymmetrical vibrator antenna is studied for two methods of its excitation. Earlier, it was shown that the 2nd and 3rd harmonics of the input signal frequency in the radiation spectrum of the plasma antenna are 10—20 dB stronger than those of a metal antenna with the same geometry. In this work, we study experimentally and by computer simulations the effect of the method of excitation of the plasma asymmetrical vibrator antenna on the spectral characteristics of the signal that it radiates. For the two excitation methods of the antenna, through an electrode and through a coaxial coupler, it was shown that the strength of the signal components at the frequency of the radiated signal and its multiple harmonics is different. The introduction of the coaxial coupler in the antenna excitation scheme allowed us to improve the coupling at the input signal frequency and decrease its components at the 2nd and 3rd harmonics. For the plasma antenna with the coaxial coupler, the difference between the 1st and 2nd harmonics was increased by almost 6 dB, and between the 1st and the 3rd ones by almost 20 dB compared to the antenna excitation scheme through the electrode.

Plasma antenna with frequency adjustment

A discharge of limited length (“plasma column”) in a gas-discharge tube filled with a rarefied gas was studied. The discharge is created due to the one-sided excitation of an extended high-frequency discharge supported by a propagating azimuthally symmetric mode of the surface wave. It is shown that a “plasma column” can be an effective plasma antenna at operating frequencies below the plasma frequency (ωp), with frequency tuning due to changes in the length of the “plasma column”.

Excitation and manipulation of toroidal dipole response in an antenna

The toroidal dipole is always overlooked due to its relatively weak interaction with the electromagnetic fields, but it actually exhibits tremendous potential for the design of advanced photonic devices. Here, we demonstrate the existence of toroidal dipole in plasma antenna system, which is rarely observed in the antenna design. It consists of a half-wavelength antenna and eight plasma rings to excite the toroidal dipole to enhance the electromagnetic radiation of the whole antenna system, whose mechanism is different from conventional antenna, which is a multiband antenna. We further confirm that the hybrid mode, which combines the toroidal dipole and multipole moments, can be dynamically adjusted to control both return loss and the opening of operating windows. This allows for flexible tuning of the multiband antenna simply by manipulating the response of the toroidal dipole. Furthermore, the toroidal dipole antenna is stable in dusty plasma, making it suitable for solving the problem of ‘blackout’ phenomena in aerospace communications, which exhibits the additional benefits of reduced cost and easier to manufacture.

Design and Application of High-Density Cold Plasma Devices Based on High Curvature Spiked Tungsten Structured Electrodes

Advances in radar technology have driven efforts to develop effective countermeasures. Plasma is recognized as a highly effective medium for absorbing electromagnetic waves. Recent research has focused on enhancing plasma element performance. This paper achieved ultra-high-density, low-pressure cold plasma with a density of 1.15 × 1012 cm−3, surpassing similar studies by more than an order of magnitude. Tungsten electrodes with high-curvature spiked structures were invented to replace traditional iron–nickel alloy electrodes, increasing plasma density by 88.2% under the same conditions. Lightweight and cost-effective tubular and annular ultra-high-density, low-pressure cold plasma devices were developed, demonstrating exceptional performance in electromagnetic wave absorption, plasma transient antennas, and radar stealth technology. The influence of plasma on electromagnetic waves and its numerical relationship were analyzed. By measuring the radar cross-section (RCS), the reduction in radar detection rates was quantified. The results show that the ultra-high-density cold plasma devices exhibit very low intrinsic RCS values, suitable for plasma antenna applications. The array of plasma elements generates a large-area high-density low-pressure cold plasma. This plasma effectively reduces the radar cross-section (RCS) of metallic equipment in the S and C bands and shows attenuation in the X band. These effects highlight the superior characteristics of plasma technology in electronic warfare. This exploratory research lays the groundwork for further defense applications.

A complete electrode model for plasma impedance probes

Plasma impedance probes measure the impedance spectrum of an antenna immersed in a plasma. The 1964 work of Balmain remains the standard method to interpret these data, using the peak in the magnitude at the upper-hybrid frequency to infer plasma electron density. The primary limitations of Balmain's model are the assumption of a homogenous plasma and a cylindrical dipole. This work presents a numerical model applicable to inhomogeneous plasma and arbitrary antenna geometry based on the cold, fluid approximation given by Balmain. This model solves Poisson's equation using the finite element method and accounts for the effects of the dipole using the plasma complete electrode model (PCEM). The PCEM is developed in this article and accounts for the voltage shunting effects of the dipole elements, the discrete current to the dipole, and the plasma sheath surrounding the dipole. The sheath is incorporated as a contact impedance between the dipole and the plasma in a manner analogous to the complete electrode model of electrical impedance tomography. The first portion of this paper presents the mathematical framework of the PCEM, starting from Maxwell's equations. The second part of the paper compares the output of this numerical method to Balmain's work and to data collected by an impedance probe in the Space Physics Simulation Chamber at the U.S. Naval Research Laboratory. The PCEM results agree with both the observed data and the prior modeling done by Balmain. An additional consequence of the numerical study is the observation that some second-order resonances not predicted by Balmain's model can be attributed to the presence of the plasma sheath.

Influence of Pressure on Plasma Antenna Resonance Wavelength

Influence of Pressure on Plasma Antenna Resonance Wavelength

Effect of the Method of Excitation of the Plasma Antenna on the Spectral Characteristics of the Radiated Signal

Effect of the Method of Excitation of the Plasma Antenna on the Spectral Characteristics of the Radiated Signal

Theory of a Square Loop Antenna in an Anisotropic Magnetized Plasma

Theory of a Square Loop Antenna in an Anisotropic Magnetized Plasma

Wideband frequency reconfigurable plasma antenna launched by surface wave coupler

A wideband reconfigurable plasma antenna excited by a surface wave coupler (SWC) operating at 13.56 MHz is presented in this study. The plasma antenna and SWC are designed and modeled in CST Studio. A detailed analysis of the SWC is carried out using CST Studio, and experimental measurements supplement the performance. This work explores the signal transmission capabilities of a plasma antenna excited at 13.56 MHz for the first time. A SWC is a two-port device that is modified for radiating electromagnetic waves through a plasma column produced at a frequency of 13.56 MHz with a coupling efficiency of 99%. The power port and signal port of the SWC are isolated for better coupling efficiency and to reduce interference. The return loss and isolation between the ports of the SWC at 13.56 MHz are −22 dB and −46.81 dB, respectively. The plasma antenna excited by a surface wave has a wider bandwidth than its metallic counterpart. It varies from 280 to 540 MHz for input plasma power ranging from 2 W to 10 W. In addition, a reconfigurability frequency span of 240 MHz for power ranging from 2 to 10 W is achieved experimentally. Moreover, we attained an enhanced peak gain of -5 dBi. The radiation efficiency of the plasma antenna is around 20%. The experimental results of the SWC and plasma antenna are in coherence with its simulations.

Experimental Characterization and Simulation of a Dipole Plasma Antenna for VHF Band and Effect of Ar–Ne Gas Composition

Experimental Characterization and Simulation of a Dipole Plasma Antenna for VHF Band and Effect of Ar–Ne Gas Composition

Research on plasma devices and antenna systems based on superlattice structures

To decrease the effect of carrier concentration on the skin depth, a new SPiN diode based on superlattice structure is discussed. Compared with traditional plasma diode, the intrinsic region of the SPiN diode is designed with SiGe/Si superlattices layer, and the thickness of the plasma islands is reduced from 80 μm to 5 μm, which dramatically reduced the design complexity and technical difficulty of microwave devices. Besides, a high-integration solid-state plasma inverted-F antenna based on this diode is also demonstrated in this paper. The resonant frequency of the inverted-F plasma antenna is in the order of 2.45 GHz, and the maximum gain reaches to 2 dB, which verify the effectiveness of the designed superlattice SPiN diode.

A Multi-Polarized Reconfigurable Plasma Antenna Array

Research on antenna reconfiguration is important in antenna applications. We present design of a multi-polarized plasma antenna with 40.68 MHz radio frequency (RF) power supplies and several discharge tubes filled with argon (neon) and mercury. Furthermore, self-made regulating circuits among the vibrators are introduced for the antenna array system. It can not only make the length of the dipole controllable but also improve the antenna gain and circular polarization (CP) performance under different lengths. Antenna arrays can be classified into linear and circular polarization by quickly adjusting the phase difference between vibrators. Both the experimental and simulation results indicate that the plasma antenna can realize impedance, pattern, and polarization reconstruction expediently. In addition, the linear polarization (LP) and CP can be transformed into each other quickly by adjusting the discharge conditions and regulating circuits. Moreover, compared with a symmetrical cross vibrator plasma antenna and a metal antenna of the same size, the proposed antenna array shows a certain gain and good reconfigurable performance within the frequency band of 150–250 MHz.

First experimental results of the PAM LHCD launcher at 2.45 GHz on EAST

This paper presents the first results of a passive active multijunction (PAM) launcher at 2.45 GHz during the lower hybrid current drive (LHCD) experiments on EAST. Good coupling performance with a power reflection coefficient (RC) ∼3% has been achieved at the plasma–antenna distance up to ∼11 cm in L-mode edge plasmas without local gas puffing near the PAM launcher. Reliable power coupling of this PAM during the edge perturbations induced by type I edge localized modes (ELMs) has been successfully demonstrated. Compared with the old full active multijunction (FAM) launcher, the new PAM can be placed ∼2 cm further away from the plasma in normal operations, which is in good agreement with the previous prediction (Li et al 2019 Fusion Eng. Des. 147 111 250), by the linear wave–plasma coupling code ALOHA (Hillairet et al 2010 Nucl. Fusion 50 125 010). The flexibility of the power spectrum by changing the phase difference between adjacent modules was validated and ray-tracing/Fokker–Planck simulations can reproduce the experimental features. The achievable power handling is as high as 25 MW m−2, although with a shot pulse length of ∼10 s. The first experiment successfully demonstrated the coupling performance of a PAM launcher at low density and this launcher construction provides helpful engineering experience for the 4.6 GHz PAM development in the near future on EAST.

Analysis of the cylindrical plasma antenna system modes in a wide frequency range

Plasma antennas have promising prospects for practical use with quick changes in their parameters in a wide frequency range. In this work, the radiation pattern of a plasma antenna system, which consists of a short linear antenna surrounded by fluorescent lamps, is analyzed in a frequency range of 0.5–1.5 GHz. In numerical simulation, the parameters of the gas-discharge plasma were used, which were obtained using the drift theory. In addition, an analysis of the radiation patterns using a simple and intuitive ring antenna array model was carried out, and the limit of its applicability was demonstrated. The experimental data were compared with those of simulation and theoretical analysis. Finally, a simulation was performed to compare the plasma antenna system with its metal counterpart. The results obtained are important for a whole class of nested antenna systems.

Fast ion generation by combined RF-NBI heating in W7-X

Good fast ion confinement in quasi-isodynamic stellarators still has to be demonstrated experimentally. In the absence of fusion alphas, auxiliary heating systems can be used to generate fast ions. For this purpose, W7-X has neutral beam injection and its newly installed ion cyclotron heating system. In practice, both systems can run simultaneously, the synergetic running of both is the focus of the current modelling development. With the upgrades to the SCENIC code described here, we find that, compared with pure neutral beam injection (NBI), the fast ion tail is significantly enhanced when radio frequency (RF) heating is enabled. But the effectiveness of heating and fast ion tail generation strongly depends on the plasma parameters and antenna frequency, which calls for further study, both numerical and experimental.