Log-periodic Antenna Research Articles

A compensation method for the consistency of multi-channel mixing circuit for solar radio observation system

The observing frequency of Ground-based Solar Radio Observation Systems (SROS) ranges from tens of MHz (10-m-wave) to tens of GHz (millimeter-wave). Due to the limitation of the ADC input bandwidth and sampling rate, the broadband solar radio signals acquired by the SROS will be segmented by mixing circuit and then processed the analog-to-digital conversion. The analog device inconsistency leads to the inconsistencies of the amplitude and phase between different channels of mixing circuits, which affects the accuracy of the receiver. The compensation coefficient of each frequency point is first calculated by measuring the deviation of the amplitude and phase between different channels, and then stored in FPGA of the receiver. The data achieved by ADC are proceed by FFT and then compensated by the compensation coefficients. The validation experiments are carried out using 150–500 MHz SROS located in Chashan Solar Radio Observatory (CSO). The amplitude difference between different channels can be as small as 0.5 dBm. The phase consistency can also be significantly improved. The practical application shows that this method can improve the consistency of the wideband mixing circuit, and can be used to correct of multi-channel consistency of the digital beam forming (DBF) for the low-frequency log-periodic antenna array and interference of the multiple antennas.

Design of Printed log-Periodic Antennas for Long Range Communication within a Wireless Sensor Network for Sea Water Quality Monitoring

In this paper the design of printed log-periodic antennas is presented. Focus is on the design of an antenna for long range communication within a wireless sensor network system for sea water quality monitoring, but the contents of the paper can also be useful at other frequencies and other applications. The difficulties in using the design procedure for log-periodic dipole antennas proposed by Carrel are discussed and some limitations are pointed out. New design hints are given, and preliminary examples of printed antennas are presented. Simulations are carried out not only for free-space but also in presence of sea and wave motion. Results show that printed log-periodic antennas can be good candidates for the intended application.

Сравнение результатов моделирования сложенной и развернутой логопериодической антенны, используемой для наблюдений Солнца

There are two antenna arrays located in Mingantu Spectral Radio Heliograph (MUSER). MUSER-I and MUSER-II cover the frequency band ranging from 0.4 to 2 GHz and from 2 to 15 GHz respectively. A third antenna array covering 30–240 MHz will be established in the coming years. A log-periodic antenna is one of the choices for MUSER low frequency band; it radiates structures capable of maintaining consistent impedance characteristics over a wide bandwidth. Due to the ability of achieving high gain, it is widely used in many broadband applications. In this program, folded and unfolded log-periodic antennas are simulated for the Meridian project. In order to improve its return loss, this antenna is optimized with the width of each pole and the height of the substrate. This optimized process has been implemented in the simulated software HFSS.

Comparing simulated results of folded and unfolded log-periodic antenna used for observing the Sun

There are two antenna arrays located in Mingantu Spectral Radio Heliograph (MUSER). MUSER-I and MUSER-II cover the frequency band ranging from 0.4 to 2 GHz and from 2 to 15 GHz respectively. A third antenna array covering 30–240 MHz will be established in the coming years. A log-periodic antenna is one of the choices for MUSER low frequency band; it radiates structures capable of maintaining consistent impedance characteristics over a wide bandwidth. Due to the ability of achieving high gain, it is widely used in many broadband applications. In this program, folded and unfolded log-periodic antennas are simulated for the Meridian project. In order to improve its return loss, this antenna is optimized with the width of each pole and the height of the substrate. This optimized process has been implemented in the simulated software HFSS.

Detection of Daytime Ionospheric Irregularities at Low Latitudes With a Multistatic HF Radar

We report a new observation of daytime ionospheric irregularities on December 27, 2009, at low latitudes in China using multistatic HF radar. The transmitter, with a horizontal polarization log-periodic antenna pointing westward, is located at Wanning (18.97° N, 110.50° E, dip angle 19°). Three separate receivers are in Sanya (18.20° N, 109.49° E), Qiongzhong (19.04° N, 109.77° E), and Tunchang (19.42° N, 110.13° E). Doppler spectra, frequency power spectra, and wavenumber power spectra from the three receivers were calculated. The main features of these observations are: 1) the irregularities observed at 12:10 (LT) had typical lengths on the scale of tens of meters and the altitude was in the range of 105–175 km, which is located in the E region and bottom of the F region; 2) the power distributions from the three receivers are consistent with the irregularities being field aligned; and 3) features consistent with a cascade of irregular spatial scales were observed. We suggest that the observed irregularity could be due to the intermediate layer modulated by electrodynamic instability.

Design and Implementation of Remote RFI Monitoring System for Ghana Radio Telescope Observatory-Nkutunse

Radio telescope receivers are sensitive instruments designed to detect very weak signals radiating from astronomical sources. These signals travel several light years and are sometimes drain by the interference of man-made and terrestrials RFI’s. This work aims at the design of a cost-effective Radio Frequency Interference Monitoring System (RFIMS) for the Ghana Radio Astronomy Observatory at Nkutunse. The design of automated RFIMS was constructed with a log-periodic antenna for receiving the electric field being radiated, Low Noise Amplifier (LNA) to amplify the weak signals for detectability, an attenuator to control the high power interfering signals, a filter to pass frequency of interest and a spectrum analyzer as backend. Ideally, telescopes are supposed to be sited at a radio quiet environment. The implementation is to continually monitor the radio space for potential interference at the telescope site for remedial actions since it has become a global candidate site by location and necessitation.

Design of a wideband microstrip nanoantenna array

This paper presents the design of a logarithmic array of microstrip nano-antennas at terahertz frequencies. For applications in which small antennas are required, microstrip antennas are preferred. However, they have a narrow bandwidth. To overcome this problem in microstrip antennas, a log-periodic nanoantenna design is presented which exhibits a wide bandwidth and ultra-compact design. This antenna is smaller in size compared to log-periodic antennas in microwave bands and comparable and better radiation characteristics. The proposed Log-periodic microstrip nanoantenna array consists of seven patch elements on a dielectric layer and are fed directly by a feed line through the branch lines connected to each of the elements. Scaling factor, τ = 0.95 is considered for this design and inset feed is used. In this structure, the substrate has a relative dielectric constant of er = 4.4 and a thickness of h = 800 nm. For good performance at high frequencies, gold is used for the design of the antenna. The considered operating frequency is 3.3 THz corresponding to a wavelength of 91 µm. Good impedance matching and a wide bandwidth of 800 GHz is obtained.

Time and Frequency Domain Simulation, Measurement and Optimization of Log-Periodic Antennas

Log-periodic antenna is a special antenna type utilized with great success in many broadband applications due to its ability to achieve nearly constant gain over a wide frequency range. Such antennas are extensively used in electromagnetic compatibility measurements, spectrum monitoring and TV reception. In this study, a log-periodic dipole array is measured, simulated, and then optimized in the 470–860 MHz frequency band. Two simulations of the antenna are initially performed in time and frequency domain respectively. The comparison between these simulations is presented to ensure accurate modelling of the antenna. The practically measured realized gain is in good agreement with the simulated realized gain. The antenna is then optimized to concurrently improve voltage standing wave ratio, realized gain and front-to-back ratio. The optimization process has been implemented by using various algorithms included in CST Microwave Studio, such as Trusted Region Framework, Nelder Mead Simplex algorithm, Classic Powell and Covariance Matrix Adaptation Evolutionary Strategy. The Trusted Region Framework algorithm seems to have the best performance in adequately optimizing all predefined goals specified for the antenna.

Compact and wideband printed log-periodic dipole array antenna using multi-sigma and multi-Tau techniques

ABSTRACTIn this paper, a wideband printed log periodic dipole array antenna (PLPDA) is designed to cover WiMAX (3.3, 3.5, and 5.5 GHz), WLAN (3.657–3.690 GHz, 802.11y), 4.942–4.948 GHz (802.11/a-j), and 5.180–5.825 GHz (802.11/a-n). Three effective techniques including MS (Multi-Sigma), MT (Multi-Tau), and Meander-line techniques for size reduction and bandwidth improvement are employed. The 10 dB return loss bandwidth of the fabricated antenna is 86% (3–7.8 GHz) and the average peak gain and radiation efficiency are 3.7 dB and 90%, respectively. The overall size of the presented antenna is 37 × 52 mm2, (0.37), where is the wavelength at the lowest frequency of the operating band.

Theory and experiment on horizontally inhomogeneous rectangular microstrip antenna

Theoretical investigation on horizontally inhomogeneous rectangular microstrip antenna is presented here. The dielectric inhomogeneity is introduced by adding two different substrate materials side by side to increase the degrees of freedom by 2 (arm ratio and relative permittivity of newly added material). and both modes are used here for theoretical investigations. The transcendental equation is derived here to predict the resonant frequency for different modes. Closed-form analytical expressions are also given to predict the far-zone electric fields for different modes. Theoretical results are compared with published results as found in the open literature, data obtained using commercially available numerical three-dimensional electromagnetic simulator high-frequency structure simulator, and the authors’ own experimental data to show the accuracy of their theory. The additional horizontal dielectric segment gives more flexibility to the antenna designer, leading to wider tuning range over conventional homogeneous RMA. Advantages of this novel antenna structure are also discussed in detail. The authors’ theory can be used (or extended) to investigate log-periodic antenna using RMAs, fractal-shaped RMAs etc.

Research on antenna for detecting the corona discharge of transmission line

Detection of corona discharge of the transmission line can reflect its health status and provide warning information for maintenance. Some existing detection methods are flawed and cannot be used widely. This study presents a new method by measuring the electromagnetic wave caused by corona discharge with RF antenna. Then a circularly polarised log-periodic antenna was designed by making two pairs of log-periodic antennas 90° orthogonal. Finally, this antenna was simulated and manufactured to detect electromagnetic signals, the result shows that the time domain signal of corona discharge is a high frequency oscillation wave and its fast Fourier transform main distributes between 200 and 350 MHz.

ARIANNA: Current developments and understanding the ice for neutrino detection

The ARIANNA experiment aims to detect the radio signals of cosmogenic neutrinos. It is running in its pilot phase on the Ross Ice-shelf, and one station has been installed at South Pole. The ARIANNA concept is based on installing high-gain log periodic dipole antennas close to the surface monitoring the underlying ice for the radi signals following a neutrino interaction. Especially, but not only in this configuration, it is essential to understand the trajectories that the signals take through the ice. We will report on various experimental evidence concerning the signal propagation in ice. We will discuss the implications for neutrino detection, results of neutrino searches and give the first introduction to a new modular simulation framework.

Machine Learning Based Antenna Design for Physical Layer Security in Ambient Backscatter Communications

Ambient backscatter employs existing radio frequency (RF) signals in the environment to support sustainable and independent communications, thereby providing a new set of applications that promote the Internet of Things (IoT). However, nondirectional forms of communication are prone to information leakage. In order to ensure the security of the IoT communication system, in this paper, we propose a machine learning based antenna design scheme, which achieves directional communication from the relay tag to the receiving reader by combining patch antenna with log-periodic dual-dipole antenna (LPDA). A multiobjective genetic algorithm optimizes the antenna side lobe, gain, standing wave ratio, and return loss, with a goal of limiting the number of large side lobes and reduce the side lobe level (SLL). The simulation results demonstrate that our proposed antenna design is well suited for practical applications in physical layer security communication, where signal-to-noise ratio of the wiretap channel is reduced, communication quality of the main channel is ensured, and information leakage is prevented.

Low-Profile Ultra-Broadband Log-Period Monopole End-Fire Antenna

This paper proposes an ultra-broadband (2–13 GHz) and low-profile log-period monopole end-fire antenna for the flush-mounted applications. 24 monopoles with a log-period rule are used to cover the whole operating frequency band, and those monopoles are printed on both sides of a low-loss dielectric layer vertically placed over a slot feeding line with wideband microstrip-to-slotline transition. The low profile is realized by bending the parts of the long monopoles so that the overall antenna size is obtained as 40 mm × 100 mm × 13.6 mm. The proposed antenna is fabricated, and the measured results agree with the simulated results very well. The measured results indicate that the proposed antenna can work at the whole 2–13 GHz band with very good end-fire radiation patterns and stable gain performances.

A Wideband Spiral UHF Coupler With Tuning Nodules for Partial Discharge Detection

This paper reports on the development and testing of a wideband spiral-shaped coupler for a partial discharge (PD) detection in the UHF spectrum. The coupler design, which is based on the log-periodic spiral slot antenna, has been optimized using finite element simulation. The following parameters have been optimized: feed location, arm termination shape, width of arm root, and termination. The unique feature of the coupler is the inclusion of tuning nodules on the spiral arms, which widen its bandwidth without the need for additional components. Tests in an anechoic chamber have shown a close agreement with the simulation results. The coupler exhibits a wide bandwidth (S11 < −9.55 dB) between 0.5–2.6 GHz and a peak gain of 4.8 dBi (at 1.35 GHz), while using an infinite balun coaxial feed, which allows for an input impedance of 50 Ω. The PD testing in the laboratory has shown that the phase resolved PD patterns acquired with the coupler are very similar to those captured with conventional PD sensors. An application of the coupler as an internal sensor in a gas-insulated busduct is detailed and a bandwidth comparison with other UHD PD sensors is provided.

A Novel Printed Dual-Log-Periodic Array Antenna for UHF Near-Field RFID Applications

A novel printed center-fed dual-log-periodic array antenna is proposed for ultrahigh frequency (UHF) radio frequency identification (RFID) applications. The proposed antenna is composed of two reversed wideband printed log-periodic dipole array antennas. Two closely spaced oppositely directed currents are thus introduced to achieve intensive and uniform magnetic fields in the near-field zone. A prototype antenna is fabricated and measured in practical application environment. The measurement results agree well with the simulations, and demonstrate that the proposed antenna is suitable to be implemented in RFID systems. The operated frequency band of the antenna is 824–953 MHz (14.5%), covering the UHF band in China, the Federal Communications Commission band, and the European Telecommunications Standards Institute band. With the proposed printed dual-log-periodic array antenna, measurement results also show that the RFID system delivers a 100% guaranteed reading rate within 2.0 cm and a maximum reading range of 19.0 cm.

A Wideband, Low-Profile Log-Periodic Monopole Array With End-Fire Scanning Beams

In this letter, we propose a wideband, low-profile phased array with vertically polarized end-fire radiation patterns. The array consists of four identical log-periodic top-hat monopole antennas (LPTMAs) and could be completely embedded within a shallow cavity for sight invisible integrated installation on metallic platforms. Simulation results show that the proposed array operates over a wide frequency band of 1.0–3.0 GHz for active voltage standing wave ratio <2.0. It also possesses end-fire radiation patterns with ±45° beam scanning capability in the horizontal plane. Prototypes of the proposed LPTMA and a uniformly spaced linear array (1 × 4) are fabricated and validated in experiments. Measured results are in a good agreement with the simulation results. The measured results demonstrate that the proposed end-fire scanning array is attractive for applications that require wideband beam scanning, excellent aerodynamic, and stealth performances.

Substrate integrated waveguide cavity‐backed log‐periodic slot antenna for Ku and K band applications

In this article, a novel substrate integrated waveguide (SIW) is used to design multifrequency cavity-backed log-periodic slot antenna. The proposed design has three layers of cavity-backed structure namely feeding SIW, resonant SIW, and log-periodic slot SIW in order to achieve low loss, high gain, and easy integration with high-frequency components. The proposed structure also includes an inductive window slot to couple the energy from feeding SIW to resonant cavity. The experimental results shows that 10-dB impedance bandwidth of 870 MHz (7.9%), 390 MHz (2.7%), 410 MHz (2.5%), 310 MHz (3.9%), and 420 MHz (2.2%) are obtained at resonant frequencies 11.25 GHz, 14.25 GHz, 15.95 GHz, 16.9 GHz, and 19.15 GHz, respectively. Also, a realized gain of around 18.24 dB is obtained at the bore sight direction. Moreover, the simulated and experimented results are in good agreement and make the antenna more suitable for Ku and K band applications.

340 GHz lens‐coupled 4 × 4 GaAs detector array for terahertz imaging applications

A 340 GHz 4 × 4 detector array based on 0.18 µm gallium arsenide technology is presented. Each pixel is composed of a planar log-periodic antenna, a Schottky barrier diode, and a pair of bonding pads. The detector array is mounted on a silicon lens and assembled onto a PCB using the authors’ novel flip-chip structure. Off-axis performances of the lens-coupled detector array are demonstrated experimentally, which agree well with the simulated ones. The detector array shows a peak voltage responsivity of 1347 V/W and a noise equivalent power of 2.1 pW/Hz1/2 at 340 GHz, exhibiting much better performance than the CMOS counterpart.

Microstrip Antenna–Oscillators Integrated with a Waveguide Built in a Dielectric Substrate

The design of a microwave oscillator based on a microstrip log-periodic antenna integrated with a field effect transistor and a waveguide built in a dielectric substrate has been developed and analyzed. The waveguide geometry provides the possibility of propagation and radiation at both the fundamental frequency of the log-periodic antenna and harmonics. Computer simulation of the oscillator design in a frequency range near resonance frequencies of the log-periodic antenna is conducted. The possibility of summation of powers of several antenna–oscillators arranged ias a linear phased array is investigated.