Monopole Array Research Articles

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.

Extension of the source scanning technique to curved rectangular panels for the vibroacoustic characterization of structures using wall-pressure plane waves

The Source Scanning Technique (SST) is an experimental method used to synthesize the vibroacoustic response of a given structure under random excitations such as the Diffuse Acoustic Field (DAF) and the Turbulent Boundary Layer (TBL) using a single monopole source. It was previously developed and validated for simple plane structures such as Flat Rectangular Panels (FRPs). However, in industrial cases, the structures of interest can be more complex. In this paper, the feasibility of the extension of SST to Curved Rectangular Panels (CRPs) is investigated. To numerically evaluate the performances of SST when generating wall-pressure plane waves (WPPWs) on CRPs, analytical developments are proposed to estimate the transfer functions between the monopole source and the CRPs. Two- and three-dimensional cases are considered and validated using the boundary element method. Then, parametric studies are carried out to determine the optimal parameters for implementing the SST process in two- and three-dimensional cases considering a conformal geometry, i.e., the array of monopoles has the same geometry as the structure of interest. The numerical results obtained are then supported by experimental investigations using a robotized system to move the monopole source. The transfer functions obtained using the proposed analytical models are compared to the measured ones, yielding relatively good agreement between the results.

Design, Development and Analysis of High-Frequency Dual-Band 4 × 1 Monopole Array Antenna

Design, Development and Analysis of High-Frequency Dual-Band 4 × 1 Monopole Array Antenna

Corrections to “Effects of Mutual Coupling on LTE MIMO Capacity for Monopole Array: Comparing Reverberation Chamber Tests and Drive Tests”

Corrections to “Effects of Mutual Coupling on LTE MIMO Capacity for Monopole Array: Comparing Reverberation Chamber Tests and Drive Tests”

Superdirective Wideband Array of Circular Monopoles with Loaded Patches for Wireless Communications.

A wideband superdirective array, composed of a two-element circular monopole configuration, is introduced. The monopoles are placed in close proximity, facing each other on a metal ground. To ensure good matching at high frequencies, two pairs of elliptical patches are added to the sides of the monopoles, enhancing the surface current of the circular patch for wideband performance. To achieve equal amplitude excitation and the desired phase difference, a wideband power divider with a phase shifter is designed to feed the antenna array. Simulation and measurement results demonstrate that the proposed wideband antenna array, operating within the frequency range of 2.94-7.93 GHz, exhibits a maximum directivity of 8.36-10 dBi, with an antenna efficiency ranging from 47.86 to 83.18% across the bandwidth. The proposed array has the advantages of miniaturization, high directivity and wideband operation and can be widely used in various portable wireless communication systems, including WLAN (5.05-5.9 GHz), ISM (5.725-5.875 GHz), 5G communication (3.3-3.8 GHz), etc.

Generation of vector vortex wave modes in cylindrical waveguides

In this paper, we propose a method to generate Vector Vortex Modes (VVM) inside a metallic cylindrical waveguide at microwave frequencies and demonstrate the experimental validation of the concept. Vector vortex modes of EM waves can carry both spin and orbital angular momentum as they propagate within a tubular medium. The existence of such waves in tubular media can be beneficial to wireless communication in such structures. These waves can carry different orbital angular momentum and spin angular momentum, and therefore, they feature the ability to carry multiple orthogonal modes at the same frequency due to spatial structure of the phase and polarization. In essence, high data rate channels can be developed using such waves. In free space, Orbital Angular Momentum carrying vortex waves have beam divergence issues and a central field-minima, which makes these waves unfavorable for free space communication. But vector vortex mode waves in guided structures do not suffer from these drawbacks. This prospect of enhancement of communication spectrum in waveguides provides the background for the study of vortex wave in circular waveguides. In this work, new feed structures and a radial array of monopoles are designed to generate the VVM carrying waves inside the waveguide. The experimental findings on the distribution of the amplitude and phase of the electromagnetic fields inside the waveguide are presented and the relationship between the waveguide fundamental modes and VVMs are discussed for the first time. The paper also presents methods for varying the cutoff frequency of the VVMs by introducing dielectric materials in the waveguide.

A Dual-Band Magnetoelectric Monopole Antenna Array Using Mode-Composite Waveguides

A novel substrate-integrated mode-composite waveguide owing two bands where only the quasi-TE10 mode is supported is presented. The waveguide geometry completely shared in the two bands is equivalent to one transmission channel at low frequencies and a pair of individual channels at high frequencies. With the aid of the waveguide, a dual-band magneto-electric (ME) monopole array with a relatively large frequency ratio is designed, fabricated and tested. Benefitting from the shared radiation structure that separately operates as 1 × 2 and 1 × 4 arrays in the low and high frequency bands, satisfying radiation features are obtained simultaneously in the two bands from 10.3 to 11.7 GHz and from 31.8 to 38.1 GHz. The proposed mode-composite waveguide and antenna array are valuable to emerging dual-band wireless applications operating at both microwave and millimeter-wave frequencies.

Compact, Wideband, Dual-Band Polarization and Pattern Diversity Antenna for Vehicle Communications

A new design approach of dual-band polarization and pattern diversity antenna for vehicle communications is presented. This antenna consists of three essential parts: Monopole array, swastika-shaped gap-coupled patch, and customized L-shaped driven dipole. Firstly, the monopole array composed of four monopoles beneath the patch, is excited by dipole-induced patch mode of the swastika-shaped gap-coupled patch so as to realize bidirectional beam in the upper band. Secondly, the swastika-shaped gap-coupled patch is reused as the main radiator of the lower band to achieve wideband broadside right-handed circular polarization (RHCP) radiation, which is excited by a pair of customized parallel-lines-fed L-shaped driven dipoles. Finally, two short-circuited branches are etched in the long arm of the L-shaped driven dipole, bringing in the out-of-band suppression improvement between the lower and upper bands. In order to verify the developed design method, a dual-band antenna with different polarization and radiation properties over two bands was designed, fabricated, and tested. Measured results indicate that the developed antenna with a compact transversal size of 0.36λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> *0.36λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> radiates broadside RHCP electromagnetic wave in 3.55-4.25GHz and bidirectional vertical polarization (VP) in 5.62-6.38GHz, which covers C-band and DSRC-band, and especially serves as a promising candidate for applications in both vehicle-to-satellite (V2S) and vehicle-to-everything (V2X) communications.

Low-RCS UWB Planar Monopole Array Antenna Based on the Optimized Design of the Conductor Layers

Using an optimized design of combining traditional copper (Cu) film and novel phase transition film vanadium dioxide (VO2), this communication proposes an ultrawideband (UWB) planar monopole array antenna with excellent stealth performance. The VO2 film exhibits two controllable phases: one with low conductivity of less than <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{3}$ </tex-math></inline-formula> S/m and the other with high conductivity of more than <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{6}$ </tex-math></inline-formula> S/m. Since VO2 has lower conductivity than Cu, antenna designs using this material will have lower radiating efficiency as a tradeoff for reducing the radar cross Section (RCS). To optimize this tradeoff, careful antenna shape design, and an innovative combination of using VO <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{2}+$ </tex-math></inline-formula> Cu films, the RCS can be reduced in a UWB without significantly decreasing the gain of the array antenna. In this work, Cu is applied in the regions supporting high current density, while phase transition VO2 film is used in areas supporting lower current density. Both the shape and size of the VO2 film are optimized. Compared with the all-Cu film counterpart, the realized gain of the VO <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{2}+$ </tex-math></inline-formula> Cu hybrid film array antenna is decreased only by an average of 0.4 dBi, maintaining the same radiation pattern in the working band of 6–9 GHz, while the monostatic RCS is reduced by about 9 dB on average across the UWB of 4–11 GHz.

Angle-of-Arrival Sensing Using a Machine Learning Enhanced Amplitude-Only System

A low-cost, low-complexity amplitude-only angle-of-arrival (AoA) sensor system is experimentally demonstrated. The sensor embeds a machine learning (ML)-in-the-loop procedure as the processing algorithm to extract both azimuth and elevation AoA information from a planar circular array. This has not been demonstrated in the open literature with the traditional AoA approaches, the same sensor’s dimensionality, field-of-view, or with as low system complexity. A four-channel receiver is designed, built, and assembled behind a simple four-element monopole array. The sensing components and ML algorithm are integrated to experimentally validate the hypothesis that both azimuth and elevation information can be determined from this simple, low-cost sensor. Moreover, a systematic procedure is introduced for the design of a deep neural network for the amplitude-only direction-finding application. Following this approach, major system complexity reductions are found—over 99% for the azimuth network and 98% for the elevation network, while still achieving 0.75° root mean square error (RMSE) in azimuth and 1.1° RMSE in elevation. Experimental results show up to 20% accuracy improvement in azimuth estimation, and 93% accuracy improvement in elevation, when compared to a lookup table-based method.

Triple Bands UWB Antenna with Minimum Printed Area for Power Harvesting Applications

In this paper, a triple-band ultra-wideband UWB eight elements monopole antenna array is proposed. This antenna array is designed with the minimum printed area and is prepared for wireless local area network (WLANs) power harvesting applications. It covers the bands of 2.4 GHz and 5 GHz, which makes it suitable for Wi-Fi frequencies to harvest their power. The eight-element antenna array dimensions are 28.5 cm by 15 cm. These dimensions are chosen for the mini-solar cell integration process. Low-cost FR4 material is used as a substrate. The proposed antenna’s measured reflection coefficient is compared with its simulated counterpart and is founded in good harmony.

Comparative study on the applicability of regularization method in ship’s magnetic signature modeling based on monopole array

In this paper, we first study the applicability and stability of the Tikhonov regularization method (TRM) and the truncated singular value decomposition method in ship’s magnetic signature inversion modeling. To further improve the noise immunity and robustness of the model, we apply an iterative regularization algorithm based on the conjugate gradient least squares (CGLS) method. Numerical simulation shows that the proposed algorithm is more applicable and can obtain better results of ship’s magnetic field extrapolation under different noise backgrounds. In the ship model experiment, the errors of the TRM and CGLS method for magnetic signature extrapolation are, respectively, 4.77% and 3.67%, showing that the proposed algorithm can improve the inversion effect of the ship model magnetic field.

Implementing a heuristic method to correct ground reflection effects observed in full-scale tactical aircraft noise measurements

In a recent study of noise from a T-7A-installed GE F404 engine, microphones along 38 and 76 m (125 and 250 ft) arcs were mounted 1.5 m (5 ft) above the ground to quantify human impact. While helpful for this purpose, the resulting multipath effects pose challenges for other acoustical analyses. For jet noise runup measurements, these effects are complicated by the fact that the noise source is extended and partially correlated and its spatial properties are frequency dependent. Furthermore, a finite-impedance ground surface and atmospheric turbulence affect interference nulls. This study applies a ground-reflection method developed previously [Gee et al., Proc. Mtgs. Acoust. 22, 040001 (2014)] for rocket noise measurements. The model accounts for finite ground impedance, atmospheric turbulence, and extended source models that are treated as coherent and incoherent arrays of monopoles. Application to the ground runup data to correct the 38 and 76 m spectra at a range of angles suggests the incoherent line source model is more appropriate at sideline angles whereas the coherent source model is more appropriate for upstream and downstream propagation. Comparisons with near-field data and similarity spectra show that, while imperfect, this method represents an advancement in correcting jet noise spectra for ground reflection effects. [Work supported by ONR Grant No. N00014-21-1-2069.]

Magnetic Hedgehog Lattice in a Centrosymmetric Cubic Metal

The hedgehog lattice (HL) is a three-dimensional topological spin texture hosting a periodic array of magnetic monopoles and antimonopoles. It has been studied theoretically for noncentrosymmetric systems with the Dzyaloshinskii–Moriya interaction, but the stability, as well as the magnetic and topological properties, remains elusive in the centrosymmetric case. We here investigate the ground state of an effective spin model with long-range bilinear and biquadratic interactions for a centrosymmetric cubic metal by simulated annealing. We show that our model stabilizes a HL composed of two pairs of left- and right-handed helices, resulting in no net scalar spin chirality, in stark contrast to the noncentrosymmetric case. We find that the HL turns into topologically-trivial conical states in an applied magnetic field. From the detailed analyses of the constituent spin helices, we clarify that the ellipticity and angles of the helical planes change gradually while increasing the magnetic field. We discuss the results in comparison with the experiments for a centrosymmetric cubic metal SrFeO3.

A Monopole and Dipole Hybrid Antenna Array for Human Brain Imaging at 10.5 Tesla.

In this letter, we evaluate antenna designs for ultra-high frequency and field (UHF) human brain magnetic resonance imaging (MRI) at 10.5 tesla (T). Although MRI at such UHF is expected to provide major signal-to-noise gains, the frequency of interest, 447 MHz, presents us with challenges regarding improved B1 + efficiency, image homogeneity, specific absorption rate (SAR), and antenna element decoupling for array configurations. To address these challenges, we propose the use of both monopole and dipole antennas in a novel hybrid configuration, which we refer to as a mono-dipole hybrid antenna (MDH) array. Compared to an 8-channel dipole antenna array of the same dimensions, the 8-channel MDH array showed an improvement in decoupling between adjacent array channels, as well as ~18% higher B1 + and SAR efficiency near the central region of the phantom based on simulation and experiment. However, the performances of the MDH and dipole antenna arrays were overall similar when evaluating a human model in terms of peak B1 + efficiency, 10 g SAR, and SAR efficiency. Finally, the concept of an MDH array showed an advantage in improved decoupling, SAR, and B1 + near the superior region of the brain for human brain imaging.

RIT Logo based Slotted PLPCMA Multi-Band Patch Antenna

A compact Printed Log-Periodic Curvilinear Monopole Array (PLPCMA) antenna having a Defected Ground Plane (DGP) is proposed and examined. The proposed array of curvilinear monopoles is designed on a FR-4 substrate having a dielectric constant of 4.4. The designed antenna is multi-band operated having its resonance in the regions of S band (2GHz to 4GHz), X band (8GHz to 12GHz) and C band (4GHz to 8GHz). The design reveals Voltage Standing Wave Ratio (VSWR) lesser than 1.5 has been achieved at resonating frequencies 2.49GHz, 3.28GHz, 6.84GHz and 8.36GHz with fractional bandwidth of 4.02, 3.66, 50.58 and 41.39 percentages respectively. The presented antenna exhibits unidirectional end-fire radiation pattern with peak realized gain of 7. 1145dBi.The measured results depicts that PLPCMA antenna has good -10dB impedance bandwidth of 158% from 1.58GHz to 15GHz (9.49:1) and suits for Wi-Fi/WIMAX UWB applications.

Design of Multi-band Compatible Trigeminal Monopole Array Antenna for Unmanned Aerial Vehicle

Compared with the performance index of UAV system antenna, a compatible trigeminal monopole array antenna is proposed. This antenna uses photosensitive resin as the substrate material, and can be made with UAV shell using 3D printing technology, realizing the integration of the antenna system and UAV. The antenna uses a trigeminal monopole antenna as the basic radiation unit, which is arranged in accordance with the Sierpinski fractal structure to form fractal radiation array. While enhancing the radiation through the array, it ensures that the antenna has a larger working bandwidth. In radiation performance test, the antenna is operating over a frequency spectrum of 1.038-11.916 GHz, and the minimum S11 is -37.92 dB. The proposed antenna has multi-band compatibility, better radiation performance, and greater performance redundancy.

Antenna-independent analytical design of a decoupled monopole array antenna with broadband harmonic suppression

• Design a coupler-based isolation network for any desired antenna-to-antenna distance using two phase regulators. • Design of a coupled structure as a new isolation system that does not connect two feed lines of the antennas to each other unlike many common methods. • Introducing a multi-functional via-less dual-stub-based network with ability to provide broadband very-advanced-matching and remove the harmonics. • A matrix-based step-by-step analysis of the proposed multi-step network is presented and required key closed-form equations are extracted. • An important feature is the coverage of all matching, isolation and harmonic-suppression conditions using the lowest number of the parameters in a compact structure. A hybrid microstrip-based network is proposed to simultaneously cover a multi-functional performance including high single-antenna matching, improved array isolation and higher-order harmonics suppression. Unlike most inductance-based isolators with destructive direct connection of two feed lines, the proposed isolator is comprised of only a thin dual-coupled-lines coupler with the ability to design for any desired antenna-to-antenna distance. A multi-variable via-less Π-shaped network is then introduced with dual-band filtering capability to significantly remove the antenna-isolator harmonics independently. A step-by-step matrix analysis with appropriate circuit conversion and equivalence is presented to easily extract closed-form equations of the key parameters as an overall design guideline. Full-wave simulations of two commercial software provide more validity for theoretical calculations. Furthermore, the bandwidths of the notch filters are investigated to obtain a broad harmonic-suppressed band. The fabricated array with optimal network occupies an area of only 0.039 λ 0 2 ( i . e . 0.12 λ 0 × 0.33 λ 0 ) and offers a highly improved matching with 25 dB S 11 bandwidth of 7.2% (2.39 ∼ 2.57 GHz). In this well-matched band, the isolation is over 22 dB with significant improvement of 36 dB compared to the primary one. Moreover, all harmonics are suppressed up to 9 GHz with measured<1 S 11 .1 dB. This efficient design is promising for high conversion-efficiency Rectenna and low-interference medical applications.

60-GHz Compact Vertically Polarized End-Fire Monopole-Based Yagi Antenna-in-Package for Wideband Mobile Communication

In this work, 60-GHz wideband, compact vertically polarized end-fire monopole-based Yagi antenna-in-package is proposed for mobile devices. The antenna was arranged like a monopole array, and the size was minimized by utilizing the image effect. Advantages of the proposed antenna structure include reduction of bond-wire loss by inserting a cavity to make the antenna and chip the same height and size reduction due to image effect. For practical use, a proposed antenna is interconnected with CMOS chip via a bond-wire interconnect. The measured results show 4.99dBi peak gain with 3.5dB fluctuation within 60GHz unlicensed band. S11 bandwidth is 10.6GHz(57.6-67GHz) which corresponds to 16% fractional bandwidth. The total volume of the antenna is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.74\times 1.14\times 0.15\lambda _{0}^{3}$ </tex-math></inline-formula> .

Space Efficient Meta-Grid Lines for Mutual Coupling Reduction in Two-Port Planar Monopole and DRA Array

Traditionally used mutual coupling (MC) reduction techniques such as electromagnetic bandgap structures, isolators and neutralization lines require extra space between radiators. Besides, metamaterial-based techniques require multi-layer arrangements. However, the proposed meta-grid lines overcomes the above demerits by integrating meta-grid lines in the ground plane itself. As a proof-of-concept, two-port CPW-fed monopole antenna array (TPCFMAA) and two-port DRA array (TPDRAA) are designed, fabricated and tested. It has been observed that the TPCFMAA has mutual coupling below −20 dB for frequency between 2.6 to 4.4 GHz. The envelope correlation coefficient reduces from 0.072 to 0.026 by integrating meta-grid lines in the ground plane of the TPCFMAA. At 3.5 GHz, the inter-element distance between the antennas is noted to be <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${0.015}\lambda _{\mathrm {h}}$ </tex-math></inline-formula> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{\mathrm {h}}\,\,=$ </tex-math></inline-formula> highest operating wavelength). The TPDRAA’s operating frequency can be tuned by changing the parameters of the annular ring slot in the excitation patch. The bandwidth of TPDRAA can be further increased by merging the two resonances of the two annular ring slots in the excitation patch. For TPDRAA, the measured −10 dB impedance bandwidth is from 5.65 to 6.55 GHz. The mutual coupling between the antenna elements is seen to be below −16 dB for an inter-element spacing of 4.8 mm, which is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.090\lambda _{\mathrm {h}}$ </tex-math></inline-formula> . The measured gain of TPDRAA within the bandwidth is from 4.17 dBi to 5.2 dBi. The TPCFMAA can be used in 3.5 GHz Internet of Vehicles (IoV) multi-user MIMO service, whereas the TPDRAA can be used for satellite communication in the 5.925 to 6.425 GHz frequency band, WiMAX in the 5.7 to 5.85 GHz band, ISM in the 5.725 to 5.85 GHz band, and WLAN in the 5.8 GHz band.