Log-periodic Antenna Research Articles

Design and research of high-frequency electromagnetic wave detection antenna for discharge of transmission lines

Abstract Overhead lines have a wide range of applications in power systems. When early insulation faults occur in the long-term operation of overhead lines, corona discharge may occur. Timely detection of corona discharge can guide maintenance personnel to discover and eliminate faults in a timely manner. The height and distribution of overhead lines are relatively high, and close-range detection cannot quickly locate the discharge area. Using radio frequency antennas to measure the electromagnetic wave signals generated by corona discharge can achieve long-distance positioning detection of corona discharge. This article uses a log-periodic antenna as the detection antenna and simulates the antenna structure to prove that its directionality, gain, and measurement frequency band meet the design requirements. Finally, the discharge detection performance of the antenna is verified through experiments.

RF Circuit Analysis of UWB Planar Log Periodic Antenna for 5G Communications Using Theory of Characteristic Modes

RF Circuit Analysis of UWB Planar Log Periodic Antenna for 5G Communications Using Theory of Characteristic Modes

Pattern reconfigurable antenna with specified main lobe deflection and stable bandwidth by using bistable composite laminates

Pattern reconfiguration of antennas has become a very important measure to improve the signal gain and working bandwidth by manipulating beam direction. Developing rational methods to find the reconfigurable structure is a key problem. In this paper, a collaborative optimization method is proposed to comprehensively consider both the geometric parameters of the bistable substrate and the size of the radiation patch. This method enables the design of a pattern reconfigurable antenna with specified main lobe deflection and stable bandwidth. Specifically, by using a two-step process, the log-periodic dipole antenna (LPDA) is conformally mapped from the planar substrate to the bistable substrate. Further investigation reveals that the main lobe deflection angle and bandwidth stability are influenced by the geometric parameters of the bistable substrate and the size of radiation dipoles, respectively. Thus, these parameters are selected as design variables for solving the proposed collaborative optimization model. The transformation between two stable configurations enables the proposed LPDA to deflect the main lobe of the H-plane pattern by 30° while maintaining consistency in the E-plane patterns. Importantly, the resonant frequencies remain unaffected and the bandwidth does not decrease during the pattern reconfiguration. Notably, the pattern reconfigurable mechanism is rooted in that the transformation between the two stable configurations alters the number and position of the dipoles in the radiation region and their current path, thereby changing the radiation direction of electromagnetic waves. The proposed collaborative optimization method has a potential application for other types of antennas and offers opportunities for various applications in the field of wireless communication.

Enhanced Gain Dual-Port Compact Printed Meandered Log-Periodic Monopole Array Antenna Design with Octagonal-Ring Shaped FSS for Broadband 28 GHz Applications

In this article, we propose a microstrip-fed printed meandered log-periodic monopole array (PMLPMA), and its dual-port configuration incorporating an octagonal ring frequency selective surface (FSS) layer. The dual-port PMLPMA antenna system has a compact structure with a total dimension of 18.75 × 18.75 mm2 and is designed to operate in the 5G n257 (28 GHz) band. The proposed PMLPMA radiator consists of five log-periodic monopole array elements, and the dual-port antenna system comprises two identical PMLPMAs placed vertically next to each other. Additionally, an octagonal ring-shaped single-layer FSS was implemented on the proposed antenna system to increase the gain across the operational band. Simulation results demonstrate that the dual-port PMLPMA antenna achieves a peak gain of about 3.5 dBi without the FSS layer, while a peak gain of 7.35 dBi is achieved when the FSS layer is augmented on the antenna. Moreover, isolation levels exceeding 30 dB are obtained for both cases between the 26.5–29.5 GHz frequency ranges. To verify the simulation results, the dual-port PMLPMA antenna system, and the octagonal ring-shaped FSS layer are also prototyped. The measurements align closely with the simulations in terms of performance criteria such as gain, bandwidth, and radiation patterns. Thus, the 28 GHz band antenna system exhibits great potential for 5G mobile applications.

Investigation of a Circularly Polarized Log-Periodic Dipole Antenna

Investigation of a Circularly Polarized Log-Periodic Dipole Antenna

Design of a Compact Log Periodic Dipole Array Antenna for Broadband and High-Power Beam Synthesis Using Superposition

This paper investigates various array beam shapes for high-power electronic warfare applications using an actual broadband array antenna. For use in a limited mounting space, a compact printed log periodic dipole array (LPDA) operating over a wide bandwidth is designed. The LPDA is then extended to an 8 × 1 array, with active element patterns (AEPs) obtained through simulation and measurement. Beam synthesis is performed by the superposition of several array patterns, which involves adjusting the weight of each AEP. To derive a synthesized array beam shape that is similar to the guided mask, the Taylor window weighting method is applied to each array pattern. Finally, beam synthesis for the flat-top beam, cosecant-squared beam, and iso-flux beam is performed using Taylor window-weighted AEPs, and the results are compared with those of beam shapes using ideal isotropic patterns. The results demonstrate that various beam shapes can be achieved for high-power electronic warfare applications using the AEPs of an actual array antenna.

A 1 bit Raw Voltage-recording System for Dedicated Observations of Transients at Low Radio Frequencies

Recently we had reported commissioning of a prototype for pulsar observations at low radio frequencies (<100 MHz) using log-periodic dipole antennas in the Gauribidanur Radio Observatory (≈77°E, 14°N) near Bangalore in India (https://www.iiap.res.in/?q=centers/radio). The aforementioned system (the Gauribidanur Pulsar System) is currently being augmented to directly digitize the radio-frequency signals from the individual antennas in the array. Our initial results using a 1 bit raw voltage-recording system indicate that such a back-end receiver offers distinct advantages like (i) simultaneous observations of any set of desired directions in the sky with multiple offline beams and smaller data rate/volume, and (ii) archival of the observed data with minimal resources for reanalysis in the future, either in the same or a different set of directions in the sky.

Diseño y Simulación de una Antena Fractal Log-Periódica para la Detección de Minas de Plástico

A fractal log periodic antenna for a Ground Penetrating Radar (GPR) is designed and simulated to evaluate the detection of plastic mines. The Brewster pseudo-angle concept is considered in the simulation to force the reflection component to a minimum value. The methodology focuses on the characterization and modeling of the transmission media and the plastic mine, in addition, the presence of the standing wave in the system is simulated to evaluate the return signal in the receiving antenna of the GPR. As a result, the multiband characteristic of the log-periodic fractal antenna and the signal-to-noise ratio (SNR) of 10,17 dB obtained for the resonance frequency of 1,35 GHz stand out. Likewise, the pseudo-Brewster angle of 70,47° minimizes the reflection of the incident electromagnetic wave in the transition between two dielectric media, with losses and dispersive in frequency (free space-ground).

Spectral Smoothness of Ground Plane Backed Log-Periodic Dipole Antennas for Radioastronomical Applications

The spectral smoothness properties of the low-frequency array of the square kilometer array (SKA), namely, SKA-Low, are an important issue for its scientific objectives to be attainable. A large array of 256 log-periodic dipole antennas, installed on top of a 42 m circular ground plane, will work as an SKA-Low station in the frequency range of 50–350 MHz. In this article, the ground plane-induced effects are examined in terms of antenna beam spectral characteristics, while different antenna placements are considered. Results are produced both at the isolated antenna and at the array level in the band 50–100 MHz, by employing an approximate method for the speeding-up of array simulations. We attempt to distinguish the ground plane effect from that of mutual coupling among antennas, which appears to be more severe at specific frequencies, using 2 figures of merit. The discrete Fourier transform (DFT) components of gain pattern ratios identify the fundamental spatial components of the ripple, while the envelope correlation coefficient quantifies the penalty to considering an infinite ground plane.

Electromagnetic performance of generalized deployable log periodic dipole antenna with mechanical errors

The primary contribution of this paper is to investigate the effect of mechanical errors on the electromagnetic (EM) performance of the generalized deployable log-period dipole (GDLPDA) antenna. The concept of the “GDLPDA” is introduced first. Additionally, an electromechanical error analysis model is developed to assess the effects of dipole machining errors and deformations on the EM performance of GDLPDA. Based on this model, positional errors in two directions along the feedline are considered. Furthermore, an electromechanical error analysis model considering dipole rotational errors on cross-polarized electric fields is established. The actual positional and rotational errors are simulated to analyze the EM performance of GDLPDA. The simulation results show that the dipole positional and rotational errors can degrade the EM performance. Specifically, positional errors reduce gain and pointing accuracy, along with an increase in the 3 dB beamwidth. Rotational errors generate cross-polarization fields, decreasing the level of the co-polarization amplitude. This insight can help antenna design engineers to optimize GDLPDA to minimize the adverse effects of error on performance.

A Detailed Design Procedure for Printed Log-Periodic Antennas with Koch Fractal Dipoles

This paper presents a complete procedure for the design of printed log-periodic antennas. An investigation on the coaxial-to-parallel-strip transition usually present in this kind of antenna is discussed in detail and it is demonstrated to be very critical for the achievement of the desired impedance bandwidth. Furthermore, in order to reduce the overall antenna size, the dipoles have been implemented based on Koch fractals. It has been demonstrated that the use of Koch fractals allowed reducing the antenna area by 25 % in comparison to the classical printed log-periodic structure. Both designs have been optimized for the frequency range 2.3 – 6 GHz, so as to cover several wireless services, such as WLAN, mobile communications and WiMAX, among other applications. Experimental results validate the proposed design strategy.

Antenna Synthesis by Levin’s Method using Reproducing Kernel Functions

An antenna synthesis application is presented by solving a highly oscillatory Fourier integral using a stable and accurate Levin’s algorithm. In antenna synthesis, the current distribution is obtained by the inverse Fourier integral of the antenna radiation pattern. Since this integral is highly oscillatory, the Levin method can be used for its solution. However, when the number of nodes or the frequency increases, the Levin method becomes unstable and ineffective due to the large condition number of the interpolation matrix. Thus, an improved scheme of the method is used in an antenna synthesis application in which reproducing kernel functions are used as the basis of the approximation function. The accuracy of the new method is verified by a log-periodic antenna example. The error and stability analysis results show that the new method is more stable and accurate than other well-known kernels, especially for a large number of nodes.

Solar Radio Spectro-polarimeter (50–500 MHz). I. Design, Development, and Characterization of a Cross-polarized, Log-periodic Dipole Antenna

The Zeeman effect has been routinely used to image and quantify the solar photospheric magnetic field (B). Such a direct measuring technique is not yet available for the corona (Lin et al. 2004). Since almost all transient nonthermal radio emissions from the corona are either partially or fully circularly polarized, observing their polarization signatures over broad frequency ranges would be of help to estimate B as a function of heliocentric height. This article aims to describe the design and development of a Cross-polarized Log-Periodic Dipole Antenna (CLPDA), an integral part of a radio spectro-polarimeter, which works in the 50–500 MHz frequency-range and to explain the tests that were carried out to characterize it. The above frequency range corresponds to a heliocentric height range ≈1.03 < r < 2.5 R ⊙ (R ⊙ = photospheric radius), wherein the numerous coronal nonthermal transients associated with space-weather effects are observed to originate. The CLPDA is used to determine the strength and sense of polarization of the received radio signal. The uncertainty involved in the determination depends on the polarization-isolation (PI) between the two orthogonal components of a CLPDA. Some of the recent advancements made in the antenna design concepts at high frequencies (∼GHz) were adopted to reduce the PI at low frequencies (∼MHz). Throughout the above frequency range, the CLPDA has a gain, return loss, and PI of ≈6.6 dBi, ≲−10 dB, and ≲−27 dB, respectively. The average PI of the CLPDA varies from −30 to −24 dB over an azimuthal angle range 0° to ±45° within which the observations are performed regularly.

LPDA-inspired Material-Geometry joint wide-angle broadband absorption based on metapyramid

The rapid development of metamaterials offers a new avenue to achieve exotic electromagnetic properties, such as perfect absorption for important stealth engineering applications. So far, there are few demonstrations of wide-angle broadband absorption, due to the stringent impedance matching requirement. Here, inspired by the concept of log-periodic dipole antenna (LPDA) for broadband emission, we propose a wide-angle broadband absorption based on both indium tin oxide (ITO) material and judiciously engineered metapyramid geometry. The strip ITO arrays on the sidewalls of metapyramid follow the quasi-LPDA strategy for gradient impedance and expands significantly both angular and spectral operating bandwidth by a cascading of multiple electric and magnetic resonances, as revealed by the rigorous characteristic mode analysis. Our experimental results show that the exotic absorption reaches above 0.9 at 45° tilted incidence for both transverse electric and transverse magnetic polarizations across the band of 8 ∼ 18 GHz. Our strategy circumvents the issues of limited-angle operation, high costs and high weight raised by metal structures, providing a new paradigm toward wide-angle broadband metadevices.

LPDA Calibration Using an UAV for Synthesizing UWB Impulses

In this letter, the possibility of synthesizing ultra-wideband (UWB) impulses with a conventional log-periodic dipole antenna (LPDA) mounted on a quadrotor unmanned aerial vehicle (UAV) was demonstrated. The formation of impulses using LPDA (bandwidth from 427 MHz to 1.01 GHz) with a duration of 1.9 ns, containing one period of field oscillations, became possible due to compensation of amplitude and phase-frequency distortions introduced by the antenna into radiated and received impulses. Compensation for these distortions was carried out by inverse filtering method after calibrating the antenna-feeder path at various heights UAV hovering above the reference reflector (brass mesh). The conductive carbon elements of UAV, located in the near field of the antenna, are indirectly taken into account during the calibration of antenna-feeder path parameters and do not introduce significant distortions into the generated impulses. The suggested method of synthesizing UWB impulses can find application in environmental remote sensing and can also be used to sharpen fronts of impulses radiated\received with LPDA.

Основные направления деятельности ООО «ТПК Элсервис» в части противодействия беспилотным воздушным судам

The article presents the main activities of TPK Elservice LLC in terms of expanding the tactical and technical characteristics of the previously developed small-sized means of radio reconnaissance and electronic warfare. A brief description of the radio reconnaissance automatic post is given. An automated complex for measuring the characteristics of log-periodic antennas is presented. Brief characteristics of the X-band radar – FMCW for solving the problems of detection and trajectory tracking of drones are given.

Simulation of Vibrating Intrinsic Reverberation Chambers Using an FDTD Conformal Mesh

This article presents an original simulation procedure devoted to the simulation of arbitrary-shaped reverberation chambers especially well suited for the analysis of vibrating intrinsic reverberation chambers (VIRC). The described method is based upon conformal finite-difference in time-domain (FDTD) modeling in order to model the rough surface geometry of the VIRC walls. On this point, we take full advantage of the performance of our in-house numerical FDTD code called TEMSI-FD and of its associated conformal mesher. First, uncorrelated geometries of the VIRC under study have been generated in order to analyze its performance as a RC from the computed <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$S_{11}$</tex-math></inline-formula> parameter of a log-periodic antenna. Second, correlated geometries have been generated in order to consider the continuous movement of the VIRC walls with a straightforward algorithm, each geometry being associated to a given instant. In both frequency and time domains, numerical outcomes demonstrate excellent agreement with experimental results available in the literature in similar conditions.

Hemispherical lens integrated room temperature ultra-broadband GaAs HEMT terahertz detector

Terahertz (THz) detection has been extensively studied in the application fields of wireless communication, non-destructive imaging and spectrum inspection, etc., in the decades. Here, we report that a self-mixing terahertz detector based on hemispherical silicon lens and antenna-coupled InGaAs/AlGaAs high electron mobility transistor (HEMT) enables wide spectrum detection, and improves detection performances. In this device configuration, the optimal log-periodic antenna is used to enhance light field in the channel, the double-gate could further adjust the carrier concentration, and the hemispheric silicon lens can concentrate the terahertz radiation in the center of the hemisphere to effectively improve the terahertz wave collection efficiency, which could improve the sensitivity of the detector. The broadband Terahertz responsivity and noise equivalent power (NEP) of the detector are characterized at the range from 0.07 to 0.82 THz at room temperature. A peak responsivity of 2 kV/W and a minimum optical noise equivalent power of 59 pW/Hz1/2 at 0.8 THz without any external field, are reached from two-terminal configuration at 0.8 THz. The minimum optical NEP of the device can be reduced to 30 pW/Hz1/2 by applying a gate voltage, realizing scanning imaging demonstration.

Research on Near Field Signal Behaviour of Localizer Antenna System

Near-field (NF) signal distribution behavior with a radius of 150 meters was studied to compare with far-field (FF) distribution characteristics. It can be found more flexible and detailed in NF than the signal from an NF monitor with only a single location. The origin of the measured value and signal detection method on the equipment was introduced in detail. The three-dimensional model was established and optimized by phase analysis as well as the measured data on-site. There was little difference between a measured distribution and a theoretical calculation in space. The change of directional weakening of the Log Periodic Dipole Antenna (LPDA) was proposed. Unequal amplitude signal synthesis together with Fresnel loss was considered to research and explain the incredible power gain. The modified 3D model is in good agreement with the measured results.

MUSER and IPS telescopes for solar and space weather observations

This paper describes the recently built solar radio spectroscopy-imaging facilities, including near future developments and upgrades, as well as the IPS (Interplanetary Scintillation) telescopes under construction in China for solar and heliospheric studies. MUSER (Mingantu spectral radioheliograph), renamed from CSRH (Chinese spectral radioheliograph) after the construction, covers 400 MHz-15 GHz frequency range which was established during 2009–2016 in Mingantu Observing Station at Zhengxiangbaiqi, Inner Mongolia of China, under the National Major Scientific Research Facility Program of China. At moment MUSER is composed of two arrays with MUSER-I covering 400 MHz-2.0 GHz with 40 4.5 m mesh antennas and MUSER-II covering 2–15 GHz with 60 2 m dish antennas. MUSER will be extended to have its third array MUSER-L covering 30–400 MHz frequency regime with 224 LPDAs (log-periodic dipole antennas) under the Meridian-II Project, which is a National Science Infrastructure Project of China, to be constructed in the current two years. MUSER will provide solar radio images monitoring the solar eruptions from solar surface into interplanetary space. An IPS telescope array is going to be built in the current two years under the same National Science Infrastructure Project of China, with the main IPS telescope of three 140 m × 40 m cylinder antennas located in MUSER site and two 30 m antennas in two nearby counties each about 200 km away. The working frequency will be at 327 MHz and 654 MHz with dual linear polarizations. The cylinder antennas will have a sky zenith angle of 60 degrees and be able to observe thousands of radio sources. The IPS telescope will provide important information about solar wind and solar eruptions from the Sun to the Earth environment. The MUSER and IPS telescopes at Mingantu Observing Station, National Space Science Center of Chinese Academy of Sciences will play important role in solar and space weather studies.