3D Radiation Pattern Research Articles

Band-Pass and Band-Stop Filter Frequency Selective Surface with Harmonic Suppression

This study investigated a frequency-selective surface (FSS) that is used to suppress harmonics affecting the performance and accuracy of radar systems. One side of the FSS features a metal grid structure, and when converted into an equivalent circuit model, it exhibits the characteristics of a band-pass filter with an L and C parallel structure. The other side of the FSS features a metallic loop structure and when represented as an equivalent circuit model, it exhibits the characteristics of a band-stop filter with an L and C series structure. The reflection coefficient (S11) and transmission coefficient (S21) of the FSS designed based on theory are compared using a CST studio suite and Keysight’s Advanced Design System. In addition, the transmission coefficients are verified through actual measurements, wherein the measured transmission coefficient is −0.1 dB at 3.0 GHz and approximately −50 dB at the harmonic frequency of 6.0 GHz. The designed FSS is attached to an actual radar system, and the 2D radiation pattern and maximum gain are measured during steering in boresight, azimuth (30∘) and elevation (30∘) directions. At 3.0 GHz, the maximum gain in boresight is 17.25 dB without the FSS and 17.12 dB with the FSS. At 6.0 GHz, the maximum gain is 12.79 dB without the FSS and 2.69 dB with the FSS. At 3.0 GHz, the maximum gain during azimuth steering is 16.13 dB without the FSS and 16.68 dB with the FSS, and the maximum gain during elevation steering is 15.74 dB without the FSS and 15.90 dB with the FSS.

Design of a Simulated Tri-Bandwidth circular patch with slot for X and C bands applications

Scientists continue to improve the performance and efficiency of microstrip antenna designs as technology evolves, aiming to improve their adaptability to different environments and constraints. These antennas play an important role in modern communication technologies and in signal path systems demonstrate development, computer modeling and testing of microstrip line and coaxial cable with G-shaped slots in the strip. The antenna was designed and simulated using CST simulation software. Antenna performance was analyzed, considering several factors such as return loss, gain, directness, bandwidth, 3D radiation patterns and more. Simulated results showed that the proposed antennas exhibit a wide frequency range, with the microstrip line feed antenna and coaxial cable obtaining a value of 61% and 65%, respectively. These two antennas exhibited remarkable gain which are 7.784 dBm and 7.787 dBm, respectively. The microstrip line achieved a maximum feed efficiency of 93.12%, while the coaxial cable achieved a maximum feed efficiency of 97.65%. The findings suggest that providing the antenna with coaxial cable as opposed to fine tape line improves its performance. Antennas with coaxial cable have wider bandwidth, higher gain, and better efficiency compared to microstrip line antennas.

Design of a compact wideband bi-directional pattern antenna for 5G applications

In this research, a wideband bi-directional pattern antenna implemented by a circular monopole encircled with an enforced-radiation circular ring incorporated with inversed L-shaped stub is designed to operate over the mid-band of 5G applications ranging from 2 to 6 GHz. It is contrived of a copper overlaid on FR4 substrate with relative permittivity of 4.3 and height of 1.6 mm. This proposed antenna is fed by a 50-ohm coplanar waveguide, which is printed on the same side of the radiated circular monopole. To further enrich the impedance matching, a pair of etched slots is added-on the ground plane near the fed line to reduce the return loss. In the study, the initial parameters are theoretically worked out, and then simulation is then performed by using an electromagnetic solutions tool to numerically discover the set of solution parameters. From the simulation results, this proposed antenna offers the |S11|<–10 dB covered the operating frequency running from 1.79 to over 8 GHz with fractional bandwidth 126.90 % and 1.74 to 7.07 GHz with fractional bandwidth 101.04 % for the simulation excluded and included SMA, respectively. It provides a linear polarization with total efficiency better than 81.5 %. After that, an antenna prototype with compact dimensions of 45×45×0.6 mm3 was fabricated and testified to validate the simulation results. The measurement results provide a stability bi-directional pattern with peak gain of 5.54 dBi covering a 10 dB return loss bandwidth of 118.5 % (1.93–7.54 GHz). Simulated |S11|, 2D radiation pattern and gain are reasonably in good agreement with experimental results. Furthermore, this proposed antenna is compared with the current compact, wideband and 5G antenna to indicate its prospective for the interested bands

Simulations on the effects of an optimized bowtie dipole antenna with an adaptive FIR filter

In the evolution of technology through the years, antennas are use in varying wireless systems have been in demand. Antennas play a great role in transmitting and receiving signals. As its application is heavily used in many days to day activities, it is important to create a cost-efficient and quick way to analyze its performance, characteristics, and relationship to different variables. As many radiation pattern acquisition devices are expensive, this simulation proposes a quick, reliable, and cost-friendly way to simulate 2D patterns in the E-plane and H-plane of a bowtie dipole antenna with an adaptive finite impulse response (FIR) filter. Through this study, the software MATLAB will be utilized to successfully simulate the radiation patterns of antennas with varying lengths. With the use of MATLAB toolboxes, the researchers aim to be able to compare different antenna lengths and determine the relationship and effect of it in the obtained 2D radiation pattern. If this method is successful various antenna applications may be implemented in the future with the use of 2D radiation pattern results.

Improvement of the Gerchberg–Saxton Algorithm Convergence in Phaseless Antenna Measurements via Spherical-Wave Filtering

The phaseless characterization of antennas enables configurations with reduced measurement efforts as the phase acquisition is highly sensitive to numerous error sources. However, both the magnitude and phase information are necessary to reconstruct the 3D radiation pattern of the tested radiating system. The two scans technique allows for accurate phase retrievals from magnitude-only measurements. In this paper, the two concentric spheres setup is considered with a Gerchberg-Saxton (GS) algorithm as phase retrieval procedure. These methods are known for their convergence problems, the price to pay for the easier, magnitude-only, measurements. A filtering approach is studied to mitigate these effects and a new, more efficient, filter is proposed. A loop of GS runs coupled with filters is shown to improve the radiation pattern reconstruction without much considerations. Validations are led on simulations and experimental data acquired using a commercial system.

Minkowski–Sierpinski Fractal Structure-Inspired 2 × 2 Antenna Array for Use in Next-Generation Wireless Systems

In this paper, the design, simulation, fabrication, and characterization study of a low-cost and directional hybrid four-element (2 × 2 configuration) Minkowski–Sierpinski fractal antenna array (MSFAA) for the high-efficiency IEEE 802.11ax WLANs (Wi-Fi 6E) and the sub-6 GHz 5G wireless system is presented. Each element of the array is separated by 0.7 λ0. The complete four-element fractal antenna array system includes designing the single-element Minkowski–Sierpinski fractal antenna using two different substrates for performance comparison and an equal-split Wilkinson power divider (WPD) to achieve power division and to form a feed network. The single-element antenna, four-element fractal antenna array, and WPDs are fabricated using a flame-resistant (FR4) glass epoxy substrate with a dielectric constant (εr) of 4.3 and thickness (h) of 1.66 mm. For performance comparison, a high-end Rogers thermoset microwave material (TMM4) substrate is also used, having εr = 4.5 and h = 1.524mm, respectively. The designed four-element fractal antenna array operates at the dual-band frequencies of 4.17 and 5.97 GHz, respectively. The various performance parameters of the antenna array, such as return loss, bandwidth, gain, and 2D and 3D radiation patterns, are analyzed using CST Microwave Studio. The fabricated four-element antenna array provides the bandwidth and gain characteristic of 85 MHz/4.19 dB and 182 MHz/9.61 dB at 4.17 and 5.97 GHz frequency bands, respectively. The proposed antenna array design gives an improvement in the bandwidth, gain, and radiation pattern in the boresight at both frequencies. In the IEEE 802.11 ax WLANs (Wi-Fi 6E) deployments and the upcoming 5G wireless and satellite communication systems, it is critical to have directional antenna arrays to focus the radiated power in any specific direction. Therefore, it is believed that the proposed dual-band four-element fractal antenna array with directional radiation patterns can be an ideal candidate for the high-efficiency IEEE 802.11ax WLANs (Wi-Fi 6E) and the upcoming 5G wireless and satellite communication systems.

Frequency reconfigurable rectangular patch antenna for cognitive radio applications

<span>A frequency reconfigurable microstrip transformed rectangular patch antenna consisting of two slots able to radiate in S-band and C-band is proposed. Spectrum occupancy is first analyzed using the data from literature and internet sources and hence spectrum holes are identified. A rectangular radiating patch is then designed for 5.8 GHz resonant frequency. A coaxial feed is used in the bottom by a suitable feed point. Two slots at an angle of +45 degree are made at the two corners. The electrical length of the patch is changed by using two varactor diodes in the slots. The varactors enable frequency reconfiguration in the band of frequencies that are unused or the spectral occupancy is very less. The return loss, voltage standing wave ratio (VSWR), and 2D-radiation patterns are analyzed for various values of the capacitances. high-frequency structure simulator (HFSS) is used for simulation. FR4 substrate which is economical, is used with height, h=1.6 mm, width W=25.33 mm, and length L=21.34 mm. On the substrate the rectangular patch is of width 15.73 mm and length 11.74 mm. The return loss and radiation patterns for different values of capacitances is presented. The tunability ratio obtained is 1.93. The results obtained agree with the standards.</span>

Parameter extraction of 3D acoustic images using a nonlinear optimization technique

In biometrics, classification techniques are based on parameter extraction from a large data set, such as fingerprints. Specifically, when using 3D acoustic images, it is necessary to extract a set of meaningful parameters. This work assumes that each significant target will have an acoustic image characterized by the 2D radiation pattern of the array and the envelope of the transmission pulse used. Under this assumption the final acoustic image can be synthesized by a linear combination of the significant targets in the scene. The work uses a non-linear optimization algorithm that obtains the parameters (power, range, elevation and azimuth) for each of the significant targets from a 3D acoustic image. Specifically, the algorithm is applied to the parameterization of 3D images of people, as a prior step to the use of classification algorithms based on machine learning.

Reconfigurable graphene-gold-based microstrip patch antenna: RHCP to LHCP

In the designed study, a reconfigurable graphene-gold-based microstrip patch antenna is proposed. Designed antenna has the ability to access a variety of right hand circular polarization, and left hand circular polarization polarizations by switching the positions of its slots. The central frequency of the antenna is adjusted to 0.92 THz according to the conditions. The main approach of the article is based on the principle that if the position of the slot is rotated 90°, the polarization will be switched from right hand circular polarization to left hand circular polarization. In the design outputs of S11 below −10 dB for the range of 0.8 THz through 1.1 THz is observed, which is desirable. Incidentally, the axial ratio is less than 3 dB in the direction of the antenna axis according to the simulation outputs. Important parameters of the antenna such as efficiency, directivity radiation pattern, matching, E-field distribution, H-field distribution, current density distribution, polar radiation pattern, 3D radiation pattern, and S11 sweep based on chemical potential changes (frequency reconfigurable) in the desired frequency domain are analysed. While for the range of 0.6 THz to 1.4 THz, the results obtained from the point of view of matching and polarization are good conditions. The chemical potential in the designs is 0.6.

Generation of OAM Waves and Analysis of Mode Purity for�G燬ub-6燝Hz燗pplications

This article presents the generation of Orbital Angular Momentum (OAM) vortex waves with mode 1 using Uniform Circular Array (UCA) antenna. Two different designs, namely, UCA-1 (4-element array antenna) and UCA-2 (8-element array antenna), were designed and fabricated using FR-4 substrate to generate OAM mode 1 at 3.5 GHz (5G mid-band). The proposed antenna arrays comprised rectangular microstrip patch elements with inset fed technique. The elements were excited by a carefully designed feeding phase shift network to provide similar output energy at output ports with desired phase shift value. The generated OAM waves were confirmed by measuring the null in the bore sight of their 2D radiation patterns, simulated phase distribution and intensity distribution. The measurement results agree well with the simulation results. Moreover, a detailed mode purity analysis of the generated OAM waves was carried out considering different factors. The investigation found that the greater the number of elements, the higher the purity of the generated OAM wave. Compared with other previous works, the proposed antenna design of this paper is very simple to design and fabricate. In addition, the proposed antennas are compact in design even at lower frequency band with very wide bandwidth to meet the requirements of 5G mid-band applications.

Long-Haul mmWave Sky Links: A Multi-Hop NFP-Based Design and Analysis

Networked flying platforms (NFPs) have emerged as a favorable solution to extend the network coverage and/or capacity in temporary scenarios, such as disasters or mega-size events, thanks to their flexibility and cost efficiency. However, in order to provide a reliable multihop link through NFPs, multiple parameters should be considered and optimized, such as the antenna gains, and the number of NFPs required to achieve a certain level of quality of service (QoS). Furthermore, the design of such parameters when considering the hovering fluctuation of NFPs becomes more challenging. In this paper, we study the performance of a long millimeter wave (mmWave) link through multiple NFPs to connect a remote area with the core network taking into account the fluctuation of NFPs. In specific, we derive the outage probability (OP) for such a system under practical considerations, such as NFP fluctuation variance, realistic 3D radiation patterns, gaseous absorption losses, number and distribution of NFPs. Furthermore, we propose a spatial formation for NFPs to reduce interference along the path. Extensive simulations are provided to validate the analytical findings and to reveal insightful trade-offs that help in designing such links.

Radiation Performance of Different Triangular Microstrip Patch Antenna Configuration Shapes Operating at 28 GHz

The radiation performance of different triangular microstrip patch antenna (TMPA) shapes such as right triangle (RTMPA), isosceles triangle (ITMPA), obtuse triangle (OTMPA), and equilateral triangle (ETMPA) operating at (28 GHz) are computed and compared using inset-fed techniques and Rogers-RT5880 substrate material of permittivity and (h=0.15 mm) height. The directivity, gain, efficiency, bandwidth, VSWR, S11 and 2D-radiation pattern for each mentioned triangular patch shapes are computed utilizing CST and HFSS method. The computed results reveal generally that the ETMPA provide better radiation performance whereas the OTMPA displays lower antenna radiation parameter values compared to the other considered ones. In addition, the antenna parameters of ETMPA with the use of coaxial probe fed are also simulated and the results are compared to those previously achieved experimentally and theoretically by other researchers. Generally, a good agreement between mentioned antenna parameter results is displayed and reliability of those achieved by CST with inset fed techniques is clearly observed. Moreover, the overall antenna parameter obtained, respectively, with CST and HFSS techniques for inset fed ETMPA are S11 (-28.68, -20.64), VSWR (1.076,1.20), gain (5.82, 6.29) dB, directivity (6.85, 7.09) dB, bandwidth (0.452, 0.369) GHz, efficiency (78.9%, 83.2%) and with a small antenna size of about (3.88 mm3) which is most reliable for 5G technology application systems.

Implementation of a reconfigurable miniaturized graphene-based SIW antenna for THz applications

In this paper, a graphene-based substrate integrated waveguide antenna is presented. The designed structure is considered very desirable for THz applications. The antenna is operated at a central frequency of 1 THz. While the structure is realized on a silicon dioxide substrate. The SIW antenna displays frequency reconfigurable capability due to the special properties of graphene in the THz regime. The designed structure also provides the ability to miniaturize and compress. While the S11 frequency response is less than −12 dB for the target range (0.1 through 2 THz). Finally, a complete report of magnetic field distribution, current density, electric field distribution, radiation efficiency, 2D & 3D radiation pattern, and graphene-based substrate integrated waveguide antenna input impedance is investigated and studied.

A Compact Triple-Band UWB Inverted Triangular Antenna with Dual-Notch Band Characteristics Using SSRR Metamaterial Structure for Use in Next-Generation Wireless Systems

A compact triple-band operation ultra-wideband (UWB) antenna with dual-notch band characteristics is presented in this paper. By inserting three metamaterial (MTM) square split-ring resonators (MTM-SSRRs) and a triangular slot on the radiating patch, the antenna develops measured dual-band rejection at 4.17–5.33 GHz and 6.5–8.9 GHz in the UWB frequency range (3–12 GHz). The proposed antenna offers three frequency bands of operation in the UWB range, which are between 3–4.17 GHz (~1.2 GHz bandwidth), 5.33–6.5 GHz (~1.17 GHz bandwidth), and 8.9–12 GHz (~3.1 GHz bandwidth), respectively. The higher resonating frequency band can be tuned/controlled by varying the width of the triangle slot, while the medium operational band can be controlled by adjusting the width of the SSRR slot. Initially, the simulated S-parameter response, 2D and 3D radiation patterns, gain, and surface current distribution of the proposed UWB inverted triangular antenna has been studied using epoxy glass FR4 substrate having parameters εr = 4.3, h = 1.6 mm, and tan δ = 0.025, respectively. In order to validate the simulation results, the proposed UWB antenna with dual-notch band characteristics is finally fabricated and measured. The fabricated antenna’s return-loss and far-field measurements show good agreement with the simulated results. The proposed antenna achieved the measured gain of 2.3 dBi, 4.9 dBi, and 5.2 dBi at 3.5 GHz, 6.1 GHz, and 9.25 GHz, respectively. Additionally, an in-depth comparative study is performed to analyze the performance of the proposed antenna with existing designs available in the literature. The results show that the proposed antenna is an excellent candidate for fifth-generation (5G) mobile base-stations, next-generation WiFi-6E indoor distributed antenna systems (IDAS), as well as C-band and X-band applications.

Performance Limits of 433 MHz Quarter-wave Monopole Antennas due to Grounding Dimension and Conductivity

Among antennas for Industrial, Scientific and Medical (ISM band) applications at 433 MHz, quarter-wave monopole is a reasonably good trade-off between size, gain, and cost. The electrical performance of the monopole is largely dependent on the quality of the ground plane (size and conductivity), which exhibits a practical limit on the achievable gain as most industrial user environments can provide only a finite ground plane of finite electrical conductivity. Establishing traceability in understanding the performance degradation due to such limits due to the grounding dimension and conductivity is becoming mandatory. To this end, this work leverages universal MATLAB in place of off-the-shelf software (HFSS or CST) for the quarter-wave monopole antenna simulation at 433 MHz parametrised with the ground plane’s dimension with respect to the wavelength (λ). Results indicate that by enlarging the ground plane’s size from 0.14 λ to 14 λ, the gain (directivity for PEC) from the 3D radiation pattern rises from 1.79 dBi, then starts levelling off at 6.7 dBi (5.78 λ), until saturating at 7.49 dBi (13 λ). The radiation efficiency and gain of various grounding conductivity scenarios (e.g., gold, aluminium, steel) are also quantified to inform antenna designers and engineers for commercial, industrial, defence and space applications.

Direction of Arrival Estimation Based on Received Signal Strength Using Two-Row Electronically Steerable Parasitic Array Radiator Antenna.

In this paper, we present a novel approach to direction-of-arrival (DoA) estimation using two-row electronically steerable parasitic array radiator (ESPAR) antenna which has 12 passive elements and allows for elevation and azimuth beam switching using a simple microcontroller, relying solely on received signal strength (RSS) values measured at the antenna output port. To this end, we thoroughly investigate all 18 available 3D antenna radiation patterns of the antenna measured in an anechoic chamber with respect to radiation coverage in the horizontal and vertical direction and propose a generalization of the power-pattern cross-correlation (PPCC) algorithm involving a high number of multiple calibration planes (MCP) as well as specific combinations of radiation pattern sets. Additionally, a new way of RSS-based DoA estimation accuracy assessment, which involves thorough testing conducted along the elevation direction when RF signals impinging on the antenna arrive from arbitrary θ angles, has been reported in this paper to verify the overall algorithm’s performance. The results obtained for different signal-to-noise ratio (SNR) levels indicate that two-row ESPAR antenna can produce, even for low SNR values, accurate DoA estimation in the horizontal plane without prior knowledge about the elevation direction of the unknown RF signals by using appropriate combinations of only 12 3D antenna radiation patterns.

Parameter-constrained DOA estimation for directional uniform circular arrays with plane-reflection effect

A new multi-parameter direction-of-arrival (DOA) estimation model with image pattern factor is proposed for directional uniform circular arrays (UCAs) in the presence of plane-reflection effect. Firstly, to accurately formulate the characteristics of the radiation pattern impacted by the plane-reflected effect, a modified multi-parameter 3D radiation pattern with image pattern factor is derived on the principle of sources reconstruction. This model is well verified in theory by comparing it with the pattern of the practical log-periodic dipole antenna (LPDA). Secondly, having introduced this radiation pattern into the response vectors, the DOA estimation method with the constrained height-to-wavelength ratio (HWR) is then formulated, which is aimed to improve the achievable estimated accuracy within the full spatial coverage. Unlike the most existing models, it is well suited to the situation when there are reflected signals impinge on the response array. Thirdly, in order to evaluate the DOA performance with the constrained parameters, the deterministic Cramer-Rao Bound (CRB) function is derived. The qualitative analysis on CRB is referenced in the design of the available parameters of antennas on the premise of the uniform DOA estimation performance. Finally, the relationships between the DOA performance and the various constrained parameters are demonstrated in the simulations. The simulation results indicate that the DOA method using the proposed model has a superior estimation performance comparing to the traditional models when reflected signals exist.

Lotus flower-shaped 4/8-element MIMO antenna for 5G n77 and n78 band applications

This paper reports a 4 × 4 and 8 × 8 MIMO antenna configuration on FR4 substrate occupying the area of 1.43λ o × 1.43λ o mm2 (f = 3.58 GHz) and 2.14λ o × 2.14λ o mm2 (f = 3.50 GHz). The proposed design is exclusively developed for 5G: n77/n78 wireless band applications. The MIMO antenna comprises of Lotus-shaped radiating element with DGS (defected-ground-structure) in-ground and the addition of slits providing boresight radiation. All the radiating elements are placed orthogonally in a 4 × 4 configuration while pairs of antennas are also placed in the same fashion for 8 × 8 MIMO antenna configuration. The high isolation of more than 16 dB is achieved by using a novel decoupling structure in the ground. Also, the MIMO antenna are characterized with diversity performance including ECC, DG, TARC, CCL and MEG achieving permissible values of <0.005, ∼10 dB, <0 dB, <0.10b/s/Hz and ∼ −3 dB respectively. The peak gain corresponds to 4.51 and 5.02 dBi with radiation efficiency of more than 80% for 4 × 4/8 × 8 MIMO antenna configuration. The proposed antenna also offers desired 2D radiation patterns in principal planes.

A Simple Method for Improving Accuracy in Determining the Beam Axis of an Antenna

The simplest method for determining the beam axis of an antenna, commonly used in measurement practice, is to search for the peak value within the 3D radiation pattern data. This paper shows that the accuracy in determining the beam axis can be improved statistically without repeated measurements. The proposed method is based on an analogy to the center of mass of a spherical region with given mass distribution. The method is straightforward and more accurate than the simple search for peak value and the competitive method of centroid, which uses level curves. The proposed method was verified numerically and experimentally, and its accuracy was confirmed.

Orthogonal Printed Microstrip Antenna Arrays for 5G Millimeter-Wave Applications.

This article presents the design of a planar MIMO (Multiple Inputs Multiple Outputs) antenna comprised of two sets orthogonally placed 1 × 12 linear antenna arrays for 5G millimeter wave (mmWave) applications. The arrays are made of probe-fed microstrip patch antenna elements on a 90 × 160 mm2 Rogers RT/Duroid 5880 grounded dielectric substrate. The antenna demonstrates S11 = −10 dB impedance bandwidth in the following 5G frequency band: 24.25–27.50 GHz. The scattering parameters of the antenna were computed by electromagnetic simulation tools, Ansys HFSS and CST Microwave Studio, and were further verified by the measured results of a fabricated prototype. To achieve a gain of 12 dBi or better over a scanning range of +/−45° from broadside, the Dolph-Tschebyscheff excitation weighting and optimum spacing are used. Different antenna parameters, such as correlation coefficient, port isolation, and 2D and 3D radiation patterns, are investigated to determine the effectiveness of this antenna for MIMO operation, which will be very useful for mmWave cellphone applications in 5G bands.