Periodic Antenna Research Articles

Design of Periodic End-Coupled Leaky-Wave Antenna With Asymmetrically Loading Unit

In this letter, a periodic end-coupled leaky-wave antenna is designed based on an asymmetrically loading unit. A simple balancing condition in the equivalent distributed circuit model is developed for the open stopband suppression by introducing a complex effective resonant frequency. The proposed balancing condition naturally satisfies both the frequency-balancing condition and Q-balancing condition in the lumped circuit model. Based on the derived formula, the physical parameters could be quantitatively determined. Subsequently, two typical periodic end-coupled leaky-wave antennas are designed, implemented, and verified experimentally. The measured reflection coefficient and the radiation results show that the open stopband at the broadside frequency is successfully suppressed.

Miniaturization design of log periodic dipole antenna based on dovetail structure

Aiming at the problems of large size and small gain of log periodic dipole antenna (LPDA) in high frequency (HF), this article introduces miniaturization technology to design a miniaturized HF broadband LPDA unit antenna with high gain. In this article, a dovetail structure is designed for LPDA to greatly reduces its transverse size, and adopts a larger scale factor and a smaller spacing factor to reduce its longitudinal size. The effects of scale factor, spacing factor, oscillator angle, parallel oscillator and erection height on the impedance characteristics and radiation performance of dovetail LPDA are studied. Finally, the feasibility of dovetail LPDA is verified by simulation and experiment, which shows that the proposed antenna size is only 7.92 × 15.52 m2, voltage standing wave ratio is less than 1.8, and gain is more than 11 dBi. The proposed dovetail LPDA has high gain, wide bandwidth, and small size, which can work independently and can also be used as the unit antenna of HF broadband antenna array.

Multilayer Dielectric Periodic Antenna Structure in a Cascade View

The spectral response of the periodic antenna structure placed in a dielectric homogeneous medium depends on the antenna geometry, the parameters of the medium, the angle of incidence, polarization, and the geometry of the excitation field. Increasing the number of antenna structure parameters can be achieved by introducing a multilayer dielectric medium with a certain number of metallized periodic surfaces located on flat boundaries between the dielectric layers. There are two complementary approaches to the analysis of such structures. In the first, the composite antenna system is analysed by constructing supermodes of the entire structure. In the second, the system is considered as a cascade assembly of flat discrete elements, i.e., the boundaries between two dielectrics, periodic metallized planes, and dielectric layers. The latter approach leads to the definition of the scattering, transmission, or impedance matrix of the entire structure by cascading the corresponding matrices associated with the individual discrete elements of the antenna structure. It is particularly useful in modelling dielectric multilayer antenna walls, where the stored data on one planar antenna element can be used many times in the analysis of various antenna systems with modified parameters of other discrete structure elements. Microstrip antennas combine field and peripheral problems and require the use of analytical methods of a high degree of complexity. Therefore, at present, there are no standard methods that can be used in engineering practice. This work is a step towards filling these gaps.

A Periodic CPW Leaky-Wave Antenna With Enhanced Gain and Broadside Radiation

In this letter, a periodic coplanar waveguide leaky-wave antenna with enhanced gain and continuous backward-to-forward beam scanning is presented. The leaky-wave antenna is made of coplanar waveguide with two symmetric transversal slots on the ground plane. The gain of the antenna is enhanced because of the radiation of the two slots superimposing in the H-plane. The relationship between Bloch impedance and characteristic impedance of the host coplanar waveguide is then investigated. By introducing a pair of matching slots, an improved impedance matching approach is presented to remove the dramatic variation of Bloch impedance at broadside frequency. Hence, the open-stop band (OSB) can be effectively suppressed and broadside radiation is achieved. Finally, a design prototype is implemented and fabricated as an experimental verification. The simulated and measured results show a good agreement. Both the reflection coefficient and radiation patterns verify that the open-stop band of the antenna is eliminated, while the gain is enhanced.

A Periodic Mirror-Reflected Circular-Polarized Leaky Wave Antenna With Dual-Beam Scanning in Dual Polarization Types

A periodic mirror-reflected circular-polarized (CP) leaky wave antenna (LWA) with dual-beam scanning in dual polarization types is reported in this communication. The unit cell of the proposed antenna consists of two oblique stubs that are orthogonally separated (90°) to create a circular polarization. In order to achieve better CP (axial ratio (AR) < 3 dB) and beam-scanning characteristics for the periodic CP antenna, a new method of adding a groove at the junction of stubs within the unit cell is introduced. To realize dual-beam scanning in dual circular polarization, a metal via is added at the end of the antenna to generate a mirror reflection. A mirror-reflected structure is fabricated and measured. The measured results show that the right-handed CP (RHCP) scanning range of the incident beam is −31° to −8° and 5° to −14°, and the left-handed CP (LHCP) scanning range of the corresponding reflected beam is 31°–6° and −6° to −15°. The measured results are in good agreement with the simulated ones.

Slot implementation on second iteration of fractal log periodic dipole antenna for UHF band application

Abstract In this paper, the design of the second iteration of Log Periodic Fractal Koch Antennas (LPFKA) with and without slot implementation is designed for Ultra High Frequency (UHF) band applications. The slot implementation is applied on each of the radiating elements to reduce the antenna’s size and to prevent the shifting of a lower frequency to a higher frequency. The antenna is operated at a frequency between 0.5 GHz and 9.0 GHz. The Computer Simulation Technology (CST) software was used to design and simulate the antenna. The performance of the antenna such as reflection coefficient, radiation pattern and gain have been analyzed. The antennas have been fabricated using an FR4 laminated board with a dielectric constant of 4.6, tangent loss of 0.019, and a thickness of 1.6mm. The results show a positive outcome, with a stable radiation pattern over the operational bandwidth and a reflection coefficient of less than -10 dB for the designed frequency.

LTCC-Based Antenna-in-Package Array for 5G User Equipment With Dual-Polarized Endfire Radiations at Millimeter-Wave Frequencies

An antenna-in-package (AiP) of endfire and dual-polarization at 28 GHz is presented. It is formed by four periodic antennas of broad bandwidth and high-isolation, fabricated by the low-temperature cofired ceramics technology. The dual-polarizations are realized by integrating a horizontal metal stripline-coupled dipole with a vertical magneto-electric monopole, incorporated into a multilayer architecture for compactness. The AiP skillfully implements vertical vias and horizontal strip lines in the cavities between antennas to improve isolation and polarization purity. This AiP has numerically been examined for endfire high gain and beam steering in user equipment (UE) applications. The prototype was measured to show good isolation lower than −25 dB from 26.5 to 29.5 GHz and agree with full-wave simulations. The antenna array is finally integrated with 1 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 4 boresight radiation microstrip antennas to form a complete UE AiP.

A periodic meandering microstrip line leaky‐wave antenna with consistent gain and wide‐angle beam scanning

In this article, a periodic leaky-wave antenna (LWA) with wide-angle beam scanning and stable gain is proposed based on the meandering microstrip line. Due to the meandering property of the microstrip line, the longitudinal dimension of the antenna is reduced. Firstly, the radiation characteristic of the meandering microstrip line is analyzed in detail. Each corner of the meandering microstrip line is modeled by a shunt capacitance and shunt radiation conductance to acquire the equivalent circuit. Then, the frequency balanced condition is investigated based on the established equivalent circuit to realize continuous beam scanning through broadside. Subsequently, the method of open-stop band (OSB) suppression is studied by introducing asymmetric perturbation on the LWA unit cell, which actually can be applied to eliminate the OSB effect in arbitrary symmetric LWAs. Finally, an antenna prototype is simulated and measured. The measured results agree well with the simulated results, validating the proposed method of OSB suppression. The measured results show that the designed antenna exhibits the beam scanning capacity of −47° to +76° with the frequency varying from 5.0 to 7.8 GHz and gain variation of 2.9 dB.

Radiation Pattern Synthesis of the Coupled almost Periodic Antenna Arrays Using an Artificial Neural Network Model

This paper proposes radiation pattern synthesis of almost periodic antenna arrays including mutual coupling effects (extracted by Floquet analysis according to our previous work), which in principal has high directivity and a large bandwidth. For modeling the given structures, the moment method combined with the generalized equivalent circuit (MoM-GEC) is proposed. The artificial neural network (ANN), as a powerful computational model, has been successfully applied to antenna array pattern synthesis. Our results showed that multilayer feedforward neural networks are rugged and can successfully and efficiently resolve various distinctive, complex almost periodic antenna patterns (with different source amplitudes) (in particular, both periodic and randomly aperiodic structures are taken into account). An ANN is capable of quickly producing the synthesis results using generalization with the early stopping (ES) method. Significant advantages in speed and memory consumption are achieved by using this method to improve the generalization (called early stopping). To justify this work, several examples are shown and discussed.

Optimization Design and Development of UHF Antenna for PD Detection in Substation

In this paper, a directional logarithmic periodic antenna is designed to meet the application requirements of local discharge detection in substation.The model of log-periodic dipole antenna was established by using high frequency electromagnetic wave simulation software, and the effects of dielectric substrate thickness, dielectric constant of dielectric substrate and patch size parameters on antenna return loss and standing wave ratio were analyzed.Finally, the dielectric substrate thickness of the antenna is 1.6mm, the material is TEflon, and the width of the assembly line is 4mm.According to the selected antenna type and size, the uHF signal receiving antenna is manufactured.

A vehicle‐mounted high power LPDA design for 8‐22 MHz applications

AbstractThe design of high‐power vehicle‐mounted log periodic dipole antenna for 8‐22 MHz use was discussed. It is shown that the antenna has a power endurance of 150 kW. With the application of the coefficients variation method, the total size of the proposal was shrunk to 12 × 18 m so that it can be mounted on a vehicle of 10 m long by an elevation tower. The voltage standing wave ratio over the entire frequency band is lower than 2.0 without utilizing any match network.

Linearly Polarized Millimeter Wave Reflectarray with Mutual Coupling Optimization

This work provides the design and analysis of a single layer, linearly polarized millimeter wave reflectarray antenna with mutual coupling optimization. Detailed analysis was carried out at 26 GHz design frequency using the simulations of the reflectarray unit cells as well as the periodic reflectarray antenna. The simulated results were verified by the scattering parameter and far-field measurements of the unit cell and periodic arrays, respectively. A close agreement between the simulated and measured results was observed in all the cases. Apart from the unit cells and reflectarray, the waveguide and horn antenna were also fabricated to be used in the measurements. The measured scattering parameter results of the proposed circular ring unit cells provided a maximum reflection loss of 2.8 dB with phase errors below 10°. On the other hand, the measured far-field results of the 20 × 20 reflectarray antenna provided a maximum gain of 26.45 dB with a maximum 3 dB beam width of 12° and 1 dB gain drop bandwidth of 13.1%. The performance demonstrated by the proposed reflectarray antenna makes it a potential candidate to be used in modern-day applications such as 5th Generation (5G) and 6th Generation (6G) communication systems.

Compact periodic leaky-wave microstrip antenna with periodic short circuits and forward-to-backward scanning capability

Compact size, elliptical polarization, a low-sidelobe-level microstrip leakywave antenna with short pins on one side of the sheet is described in the paper. The suggested antenna consists of 7 sheets that are periodically put on the antenna structure, with one of the edges of the sheet being incorporated with short-circuit pins. The proposed antenna has effective decrease in antenna size good scan capability, and reduction in sidelobe level in comparison with another types of antennas. A set of simple and effective equations is used to determine the operating range of the antenna. As elucidated by simulation results, the scanning process is carried out from 11° to –15°, at the rate of 26% as the frequency changes from 22.8 GHz to 27.8 GHz.

Optimization of Coupled Periodic Antenna Using Genetic Algorithm with Floquet Modal Analysis and MoM-GEC

In this paper Genetic Algorithm has been integrated with Fouquet modal analysis to optimize radiation pattern of coupled periodic antenna. Floquet analysis is used with MoM-GEC (Moment-Generalized Equivalent Circuit) method to study a finite periodic array with uniform amplitude and linear phase distribution. This method is very advantageous for studying large antenna array since it considerably reduces the computation time and the number of operations. In this way, Genetic algorithm is introduced and combined with Floquet analysis to optimize the radiation pattern distribution of this coupled periodic antenna. The goal of the optimization is to provide a better radiation characteristic for the coupled periodic antenna with maximum side lobe level reduction.

A dual-beam steering one dimensional periodic leaky-wave antenna for large coverage

This paper proposes a dual-beam leaky-wave antenna (LWA) based on substrate integrated waveguide (SIW) technology. The unit cell of the proposed SIW LWA consists pair of transverse and longitudinal slots etched on the top and bottom surface of the SIW. The unit cell characteristics of LAW have been investigated using dispersion analysis. As a result, the open stopband (OSB) problem is suppressed in the broadside direction. As a result, the dual radiating beam of LWA scans the entire space of the elevation plane (XZ plane) without any severe gain degradation at the broadside and endfire. The proposed SIW LWA antenna works in the band of 11.5 to 15.5 GHz with a peak gain of 13 dBi. The measured results are in accord with simulation results.

Second Iteration of Slotted Fractal Log Periodic Dipole Antenna for UHF Digital TV Band Application

This paper discusses the simulations and measurements of the antenna with and without slot implementation in terms of reflection coefficient (S11) and radiation pattern. The slot implementation on each of the radiating elements on the 2nd iteration log periodic fractal Koch antenna (LPFKA) was described in this paper. This method is utilised to reduce the antenna's size while also preventing the lower designated frequencies from shifting to the higher band as the iteration increases. The antenna is designed to test and observe performance in the Ultra High Frequency (UHF) band, which ranges from 0.5 GHz to 3.0 GHz. Computer Simulation Technology (CST) software is used to design and model the antenna, which was then built using the wet etching technique. The antenna's substrate is made of FR-4 laminated board with a dielectric constant of 4.6, tangent loss of 0.019, and a thickness of 1.6mm. The results demonstrate good agreement, with a steady radiation pattern over the operational bandwidth and a reflection coefficient of less than -10 dB for the frequency range of interest. The antenna is being tested with Digital TV decoder and the result is observed towards the picture of the Digital TV.

Modified 16-Quasi Log Periodic Antenna Array for Microwave Imaging of Breast Cancer Detection

In this paper, an effective system for microwave imaging of breast tumor detection using modified 16-planar log periodic antenna (PLPA) array is presented. The modified PLPA operates in the band from 2 to 5 GHz with stable directional patterns in the end-fire direction. Once the results of a single antenna element have been validated, the design is extended to include 16 antenna elements. All 16 transceiver antennas are vertically placed around the phantom in a circular manner where one antenna acts as a transmitter and the rest work as receivers. Delay and Sum (DAS) algorithm is used for post processing the acquired scattered signals from the sensors to reconstruct the image of the breast and to identify the existence of breast tumors. The electromagnetic simulators CST and HFSS are used to design the system, while MATLAB is used to process the data. The developed PLPA array-based microwave imaging system performs admirably, making it one of the most effective systems for detecting tumor cells.

A Compact Log Periodic Planar Dipole UHF Array Sensor for Partial Discharge Measurements

A compact log periodic planar dipole UHF array antenna from 500 MHz to 2.2 GHz for partial discharge measurement in power transformers is presented in this paper. The compactness of the designed antenna is achieved by shaping the arms and tuning selected dipole elements of the array to fill the unoccupied areas. Shaped dipole arrangement results in additional capacitance between the antenna elements enhancing the bandwidth. The designed antenna achieves a fractional bandwidth of 126% and the size is ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.495\lambda _{0} \times 0.63\lambda _{0} \times 0.0144\lambda _{0}$ </tex-math></inline-formula> ) at center frequency of 1.35 GHz. The proposed antenna is experimentally validated on FR4 3.2 mm thickness substrate. The measured gain of antenna is 4 ± 0.5 dBi over 800 MHz to 2.2 GHz which provides lower variation in measured partial discharges. The effective antenna height of the proposed antenna is measured to be over 15 mm. The measured return loss is better than 10 dB over the frequency range. Moreover, partial discharge measurements with oil filled test objects demonstrate that the designed antenna can receive partial discharge signals effectively.

Ultrasensitive critical-state of upconversion nanoparticles assembled on plasmonic antenna arrays for rapid and accurate determination of NH3

Plasmon enhanced upconversion luminescence has drawn extensive attention due to its advances in the fields of optical sensors, bio-detection and medical diagnosis. However, the coupling state between plasmon and upconversion emission is never clearly revealed. Here, we report a novel critical state in plasmon coupled upconversion nanoparticles (UCNPs) that has a long lifetime and is highly stimuli-responsive. The critical state is generated through the precise control over the coupling between plasmonic local field and optical near field. Platinum (Pt) film with thickness of ~7 nm is deposited on photonic crystals to form a periodic plasmonic antenna arrays. UCNPs with inert shells are embedded in plasmonic antenna arrays with a tunable plasmon coupling distance via the thickness control of inert shells. An ultrasensitive critical state is observed for the coupling distance of ~10 nm between Pt film and NaGdF4:Yb/Er luminescent core, accompanied with light confinement by NaYF4/NaGdF4 heterojunction shells. This critical-state can be employed as an ultrasensitive route for fluorescent detection of NH3 and the lowest detection of 0.47 ppm can be achieved that is about 34 times lower than ever reported.

Parametric Analysis of Linear Periodic Arrays Generating Flat-Top Beams

Several synthesis techniques are available to optimize amplitude and phase excitations of periodic linear arrays to generate flat-top beams. Clearly, the optimal tapering depends on design parameters such as the array length, the number of array elements, the beam flatness, the beam width, the side lobe levels, and others. In this paper, in order to derive useful guidelines and rule of thumb for the synthesis of periodic array antennas, relations between these parameters are derived employing linear programming techniques, which guarantee optimality of the solutions. Such relations are then plotted and used in some design examples.