Log-periodic Antenna Research Articles

A new printed log‐periodic dipole array ( PLPDA ) antenna with bandwidth broadening and gain improving

A broader impedance bandwidth and higher gain printed log-periodic dipole array antenna fed by half-mode substrate integrated waveguide (HMSIW) is proposed in this letter for ultra-wideband (UWB) wireless communication applications. The bandwidth of the reference antenna (5.1-11.4 GHz) is expanded by 1.3 GHz by introducing a new resonance frequency with additional patches. Moreover; gain is enhanced over full band by attaching metal plate to narrow beam and adding directors to attract energy radiated by dipoles. A simulation analysis of the improved antenna with broader bandwidth of 4.1 to 11.7 GHz and higher gain is presented, along with a design procedure and experimental results. Measurement results are consistent with simulation results, which verifies the feasibility of this technique.

Design of Log Periodic Dipole Array Antenna Ranging from 30 to 150 MHz

This paper describes construction of 16 element frequency independent and high bandwidth Log Periodic Dipole Array antenna which works within the frequency range of 30 to 150 MHz. The antenna of gain 8 dBi is designed by calculating the parameters from Matlab. Matlab program is used to calculate the parameters like length of elements, separation between elements, theoretical impedance, standing wave ratio, etc. Thus, the designed antenna was fabricated. The antenna element is a cylindrical aluminum pipe of diameter 9mm and the boom used is rectangular antenna pipe of dimension 1”X1”. Fabrication also includes other materials like M-seal, zip tie, etc for physical stability of the antenna. Log Periodic Dipole Array antenna design described in this paper is fed with 75 ohm coaxial cable to 1:1 balun. Balun is also used for impedance matching between the antenna and coaxial cable. Antenna analyzer is used to measure Standing Wave Ratio and Impedance which are found to be 1.623 and 71.5625 ohm respectively. The antenna can be a receiver or a transmitter type for operating with the signals within Very High Frequency band.

Vivaldi End-Fire Antenna for THz Photomixers

We propose a broadband end-fire antenna for continuous-wave terahertz (THz) photomixing–based devices working in the frequency range of 0.5–1 THz. A compact Vivaldi antenna is presented that does not require any hyper-hemispherical silicon lens to collect and collimate THz radiation unlike the conventionally used broadside antennas. The antenna is tailored to radiate THz into or receive radiation from a dielectric waveguide placed in close vicinity of it. The antenna is fabricated on an indium phosphide (InP) substrate. A silicon (Si) superstrate is used to improve the directionality of the radiated beam. THz power coupled into Si waveguides is measured using two different techniques between 0.1 and 1.15 THz. Firstly, the waveguide is placed in the optical path of a 1550 nm based continuous-wave THz setup with a commercial broadside emitter, focusing optics, and a detector fabricated on the InP substrate with log-periodic broadside antenna. Secondly, the waveguide is placed in direct contact with the designed Vivaldi antenna–based THz receiver and using the commercial broadside emitter as a source. It is observed that the direct coupling technique using the Vivaldi end-fire antenna outperforms the optically coupled approach at frequencies higher than 668 GHz. Efficient THz photoconductive sources and receivers based on the designed compact Vivaldi end-fire antenna will be suitable for launching THz power into on-chip THz circuitry and for compact THz systems.

Proof of the density tapering concept of an unequally spaced array by electric field distributions of electromagnetic simulations

ABSTRACTThe design method of an unequally spaced array was based on the density tapering in the textbook “Antenna theory” in 1969. The effects on grating lobe reductions were shown by radiation pattern calculations. However, no proof for the achievement of density tapering was shown. In this paper, through direct comparisons of the objective amplitude distribution with electric field distributions by electromagnetic simulation, density tapering is examined. A log-periodic dipole antenna operating from 900MHz to 2500MHz is designed for the array element. The unequally spaced 31-element array antenna is used for calculation. At many kinds of density tapering and many frequencies, calculated electric field distributions in a near-field region of the array antenna agree with the given density tapering distributions. The paper results show that the density tapering is achieved from 900MHz to 2000MHz and the effects of grating lobe reductions are ensured from 900MHz to 2500MHz.

Generation of Noiselike Microwave Signals in Microband Antenna Generators

Abstract—The study investigates the possibility of generating noiselike signals in the centimeter wavelength range using antenna generators built on a log-periodic microstrip antenna integrated with a field-effect transistor. The conditions for the occurrence of noiselike generation are experimentally determined. The possibility of expanding the noiselike spectrum using low-frequency noise modulation is studied. Noiselike generation was experimentally obtained in the centimeter wavelength range with a spectral width of up to 2 GHz.

Design of a Slotted Waveguide Antenna by Means of VBScript Scripting Language Macros in CAD Ansys HFSS

Introduction. Modern antenna devices contain a large number of repeating elements. The process of development of CAD models of such devices requires repeatedly performed operations that is a routine task for an engineer. Therefore, the problem of repeating operations automation arises when constructing antenna models with periodic structures.Aim. To demonstrate the automation of slotted waveguide antennas design process in CAD Ansys HFSS.Materials and methods. In order to determine the dimensions of the slotted waveguide antenna the energy method was used. Automation procedure of the design of the slotted waveguide antennas in CAD Ansys HFSS using the Visual Basic Scripting Edition macros was presented.Results. In order to design and edit slotted waveguide antennas in CAD Ansys HFSS four macros in the VBScript language were established: for slot subtraction from a broad wall of a rectangular waveguide at given coordinates; for removing the original slots created using the previous macro; for drawing a polyline passing through the centers of the slots, in order to verify the antenna’s near field realized distribution; for inclined slot subtraction from a narrow wall of a rectangular waveguide at given coordinates. Results of the macros usage were presented.Conclusion. The above mentioned macros allow one to automate the routine steps during the process of creating and deleting objects while designing an antenna model with periodic structures in CAD Ansys HFSS. Specified procedures for creating macros could be extended to a wide class of tasks related to the studies of characteristics of electromagnetic structures including repeating objects (phased antenna arrays, reflective arrays, slotted waveguide antennas, fractal antennas, log-periodic antennas, multi-layer lens antennas, ladder-type microwave filters).

Implementation of FMCW radar at low frequencies

FMCW radar is a low power technique for distance measurement suitable for many applications. At low frequencies, FMCW (Frequency Modulated Continuous Wave) radar can penetrate shadow zones or complex media such as forest. The need for large bandwidth in the measurements may require the use of log periodic antennas. In this study, signal processing and calibration are implemented in Labview, in combination with a USRP (Universal Software Radio Peripheral). A USRP is a form of interface between the RF hardware and the computer. The total bandwidth and the resolution are increased by reusing the bandwidth of the USRP.

Compact printed log-periodic dipole antenna (LPDA) with T-shaped arm for wide band applications

Compactness of printed log-periodic dipole antenna (LPDA) is an essential requirement in developing low-weight communication system. With this aim, in the present work, we utilized two-step approach to reduce size of this kind of antenna. First, to achieve compactness, a maximum apex angle was taken for the desired gain of 6 dBi, which reduces the boom length to minimum possible value. Secondly, after fully optimizing the width and length of each dipole, a T-shaped arm is introduced in place of straight dipole arms. For comparison, initially printed LPDA is designed with full arm structure of gain 6.5 dBi in 1.5 to 3.5 GHz band using CST Microwave Studio. In T-shaped arm LPDA, the antenna size eventually reduces by 82% compared to full arm structure, which offers a bore sight gain level varies from 2 to 4.5 dBi in the frequency band of 1.8 to 3.5 GHz. Simulation analysis are discussed in detail along-with a size comparison of various printed LPDAs. The measured results of the fabricated LPDA with T-shaped arm are found to closely match with the simulation results.

Test-Driven Design of an Active Dual-Polarized Log-Periodic Antenna for the Square Kilometre Array

An active dual-polarized Log-Periodic antenna has been designed to meet the requirements of the low-frequency (50 – 350 MHz) radio telescope of the Square Kilometre Array (SKA). The integration of antenna and low noise amplifier has been conceived in order to achieve a high degree of testability. This aspect has been found to be crucial to obtain a smooth frequency response compatible with the SKA science cases. The design has also been driven by other factors such as the large-volume production (more than 130 000 antennas will be built) and the environmental conditions of the harsh Australian desert. A specific verification approach based on both wideband radiometric spectral and spatial measurements in relevant laboratory and in-situ conditions has been developed. Electromagnetic analyses and experimental results exhibit a very good agreement. In December 2019, this antenna was part of the reference solution for the System Critical Design Review of the SKA.

Design and Performance Analysis of Printed Square Log Periodic Array Microstrip Patch Antenna at 2.5 and 3.5 GHz

Design and Performance Analysis of Printed Square Log Periodic Array Microstrip Patch Antenna at 2.5 and 3.5 GHz

Series YBCO grain boundary Josephson junctions as a terahertz harmonic mixer

Josephson devices have demonstrated the capability to work as harmonic mixers at terahertz frequencies. Low temperature devices, in particular Nb–Nb point contacts have proven particularly successful. However, practical applications of these devices have been limited by the need of utilizing liquid helium. To overcome this limitation we have investigated the use of high-Tc devices. In this paper, we report mixings up to the 154th harmonic at zero-bias in a series of YBa2Cu3O7−δ (YBCO) grain boundary Josephson junctions. We have integrated a meander series of three bicrystal YBCO Josephson junctions with a log-periodic antenna. When properly operated, this configuration allows to reach a harmonic number much higher than what possible with a single junction. This shows that the mixing performance benefits from the synchronous operation which also results in an improvement of dynamic range. We believe that the integration of a higher number of phase-locked junctions may further improve the mixer’s performance. Future studies should investigate the effect of higher number of junctions on the mixer performances, as well as the effect of the meander length.

Efficient Simulation of Large Irregular Arrays on a Finite Ground Plane

An efficient method is presented to take into account the radiation pattern deformation due to the presence of a finite ground plane lying under an antenna array and above a layered dielectric medium. The interactions between the antennas and the ground plane are computed using two main algorithms: on one hand, the near-field interactions are carried out using inhomogeneous plane waves, and on the other hand, a new formulation based on an analytical Hankel transform is derived to handle the intermediate-field interactions. This formulation expresses the electric field as a finite series of Hankel functions and associated Anger–Weber functions. The method is validated here for the second version of the square kilometer array (SKA) log-periodic Antenna (SKALA2) and then applied to an SKA low-frequency station (SKA1-LOW).

Grain Boundary Josephson Junction Harmonic Mixer Coupled With a Bowtie Loaded Meander Antenna With Zero-Bias Operation

The high- T c superconducting (HTS) bicrystal YBa2Cu3O7–δ (YBCO) zero-bias-operation Josephson junction (JJ) harmonic mixer coupled with a bowtie loaded meander antenna (BLMA) is proposed and studied at 0.21 THz. When the JJ mixer coupled with the BLMA, the maximal harmonic number increases up to 146 with the conversion efficiency of −63.6 dB at the bath temperature around 4.6 K compared to a mixer coupled with a log-periodic antenna (LPA) of only a maximal harmonic number of 46 with the conversion efficiency of −71.6 dB. The mixer coupled with the BLMA has a higher order harmonic mixing with a lower local oscillator (LO) power of 1.26 dBm, which further illustrates its superiority to that coupled with a LPA with the LO power of 5.59 dBm. The experiment verifies the merits of the JJ harmonic mixer operating at zero bias as a promising device in terahertz regions.

Multiresonant Chipless RFID Array System for Coating Defect Detection and Corrosion Prediction

In this article, a fully passive, wireless solution for out-of-sight pipeline monitoring is presented. By predicting corrosion before its occurrence, a proactive response may be taken to mitigate the chance of an environmental disaster. The chipless radio-frequency identification system is a combination of a tag ID, consisting of an array of six rectangular spiral resonators, and a tag antenna consisting of two cross-polarized novel patch antennas etched on a skin-thin microwave laminate. The tags are grounded on a carbon steel pipeline coated with $\text{3 mm}$ Teflon (polyethylene-like electrical characteristics). The proposed system exhibits robust capability to create frequency signatures to detect and monitor defects underneath the pipeline coating owing to water ingress that could eventuate to corrode the pipeline. The reader antenna above the pipeline comprises two identically cross-polarized log periodic dipole antennas with the intent to remotely capture resonances of the tag ID in real-time for early detection and prediction of potential pipeline exposure to moisture. The proposed structure provides low-cost real-time solution.

A Planar Low-Profile Log-Periodic Array Based on Cavity-Backed Slot

A planar low-profile log-periodic antenna based on cavity-backed slot is proposed in this letter. The slot element is made of a microstrip patch on a large ground plane with three edges shorted and one edge open. It is excited by a probe protruding into the cavity from the back of the ground. Through choosing different length and width, each slot element of the array can resonate at different frequency with a same height. A meandered microstrip line on the bottom is used to feed the array, achieving endfire radiation with wide bandwidth. The proposed antenna has been fabricated using printing technology. Measured results show that an operating frequency band from 6.9 to 17.4 GHz (2.52:1) for VSWR λL at the lowest operating frequency are obtained. The proposed array has a good overall performance of wide bandwidth, low profile, and planar structure with easy printing fabrication process, which may be useful for the demand of endfire radiation with low profile.

Results of work of new spectropolarimeter for solar radio emission observations in the range 50–500 MHz

Ground-based observations within meter radio range are of importance for understanding processes occurring in the solar corona.
 We present concepts, block diagram, and results of first observations of the Solar Spectropolarimeter of Meter Range (SSMD), launched for solar observations in the range 50–500 MHz in April 2016. The main purpose of this work was to develop an up-to-date digital radio spectropolarimeter able to record the full Stokes vector for sporadic solar phenomena taking place in the 50–500 MHz range.
 We use a crossed log periodic antenna to detect solar radio emission. This antenna can simultaneously obtain horizontal and vertical polarization components. The main part of SSMD is a digital receiver based on an FX correlator architecture. We use the Fast Fourier Transform (FFT) algorithm based on the real-time pipeline circuit to construct amplitude dynamic spectra (intensity vs frequency and time).
 SSMD has 4608 frequency channels with 97.66 kHz channel bandwidth and 97.66 kHz spacing. Time resolution is 1 s. The spectropolarimeter has a 50–500 MHz range. It can record the full Stokes vector. At present, SSMD observes two of four parameters in regular mode (I and V). We have observational data since 2016. The catalog development is in progress.
 We plan to improve time and frequency characteristics, record all Stokes parameters, and conduct a calibration. We are working on providing access to the data archive via the Internet.

Результаты работы нового спектрополяриметра для наблюдения солнечного радиоизлучения в диапазоне 50–500 МГц

Ground-based observations within meter radio range are of importance for understanding processes occurring in the solar corona.
 We present concepts, block diagram, and results of first observations of the Solar Spectropolarimeter of Meter Range (SSMD), launched for solar observations in the range 50–500 MHz in April 2016. The main purpose of this work was to develop an up-to-date digital radio spectropolarimeter able to record the full Stokes vector for sporadic solar phenomena taking place in the 50–500 MHz range.
 We use a crossed log periodic antenna to detect solar radio emission. This antenna can simultaneously obtain horizontal and vertical polarization components. The main part of SSMD is a digital receiver based on an FX correlator architecture. We use the Fast Fourier Transform (FFT) algorithm based on the real-time pipeline circuit to construct amplitude dynamic spectra (intensity vs frequency and time).
 SSMD has 4608 frequency channels with 97.66 kHz channel bandwidth and 97.66 kHz spacing. Time resolution is 1 s. The spectropolarimeter has a 50–500 MHz range. It can record the full Stokes vector. At present, SSMD observes two of four parameters in regular mode (I and V). We have observational data since 2016. The catalog development is in progress.
 We plan to improve time and frequency characteristics, record all Stokes parameters, and conduct a calibration. We are working on providing access to the data archive via the Internet.

Visualizing the Intensity Distribution of a Microwave Field Using a Microstrip Rectenna with a Schottky Diode

A microwave radiation intensity indicator based on an antenna-coupled detector (rectenna), an amplifier, and a semiconductor light-emitting diode was constructed and tested. This device is a hybrid integrated circuit, where a microstrip log-periodic antenna on a dielectric substrate also serves as a mechanical carrier. The possibility of visual determination of the shape of the antenna radiation pattern and the shape of an object based on the reflected radiation intensity was demonstrated experimentally at 10 and 30 GHz.

DESIGN AND MANUFACTURED OF LOG PERIODIC DIPOLE ARRAY (LPDA) ANTENNA AT 400 MHz - 800 MHz FREQUENCY AND ITS IMPLEMENTATION ON TELEVISION ANTENNA

In this study the designed Log-Periodic Dipole Array antenna (LPDA) in the frequency range 400 MHz up to 800 MHz with 7dBi Gain. For the purpose of point to point communication required antenna that has directivity and for wideband telecommunication system required a wideband type antenna. At a gain of 7 dBi, the wider the frequency range then the total length of the Log-Periodic Dipole Array (LPDA) antenna structure is also longer. The design of the Log-Periodic Dipole Array (LPDA) antenna operates at λ / 2 in the 400 MHz - 800 MHz frequency range and has the ideal VSWR value (VSWR ≈ 1) so that the antenna and transmission line are matched. The advantages of the Log-Periodic Dipole Array (LPDA) antenna itself is to have a wide bandwidth and geometry value following a certain comparison. DOI : https://doi.org/10.26905/jeemecs.v2i2.3126

Information Recovery Using Electromagnetic Emanations From Display Devices Under Realistic Environment

In this paper, an information recovery process using a horizontal and vertical synchronization frequency detection algorithm, a multiple frame average technique, as well as an image skew correction process is presented. The validity and effectiveness of the proposed procedure are demonstrated using liquid crystal display monitors and a log-periodic dipole array antenna with software-defined radio equipment. In addition, it is shown that real-time video information recovery is possible from a distance of 10 m behind a concrete wall.