Radiation Pattern Research Articles

An ultra-wideband 1-D monopulse antenna based on tightly coupled dipole linear array

A low-profile and ultra-wideband (UWB) 1-D monopulse antenna based on the tightly coupled dipole linear array (TCDLA) is proposed in this paper. First, a compact UWB monopulse feeding network is discussed. It consists of a UWB monopulse comparator and a pair of miniaturized 1-to-4 power dividers with tapered baluns. Then, a TCDLA element with frequency selective surfaces (FSS) superstrates is designed for radiation. Meanwhile, the feeding network is arranged at the bottom layer to avoid spurious radiation on radiation patterns. Finally, by connecting the feeding network and radiation part, a UWB monopulse antenna prototype is fabricated and measured. The proposed monopulse antenna array achieved an 82.35% (5-12 GHz) shared bandwidth and the isolation is greater than 16 dB. The measured results are in good agreement with the simulated results.

Environmental factors shaping alpine plant adaptations

Alpine ecosystems are distinct and demanding settings that are defined by severe climatic extremes, such as frigid temperatures, intense radiation, and restricted nutrition supply. The adaptations of alpine plants are finely tuned responses to the unique environmental challenges they face. By delving into the intricate interplay between temperature, UV radiation, soil conditions, and precipitation patterns, are valuable insights into the resilience of alpine ecosystems. Such knowledge is not only crucial for advancing ecological understanding but also for informing conservation and management strategies in the era of global environmental change. We have covered all the abiotic factors affecting plant growth and development in alpine and subalpine area in this mini review. It will be beneficial for researchers, industrialists, ecologists and agriculturists.

A compact ultra-wide band fractal antenna for breast cancer detection applications

A compact ultra-wide band antenna for breast cancer detection in bio-medical applications is presented in this study. The proposed antenna is printed on 1.6 mm thick FR4 substrate with a dielectric constant of 4.6 and tangential loss of 0.02. The uniform ground plane on the substrate (PCB) has been altered by shortening its length and making minimal changes to its side edges in order to improve overall bandwidth. The suggested antenna is functioning from 3 to 10.2 GHz which covers the ultra-wide band recommended by Federal Communication Commission (FCC) over the 10 dB impedance bandwidth. Additionally, the antenna has a significant overall gain of 3.2 dBi and an overall radiation efficiency of between 89 % and 92 %. Furthermore, the antenna maintains a uniform radiation pattern across its operating band. Parametric research has been conducted on the different parameters to tune the antenna into the required operating band, and placement analysis of the antenna is then investigated by assessing specific absorption rate (SAR).

Development and investigation of a compact band-notched MIMO antenna attaining wideband isolation for UWB applications

The sequential layout of a portable ultra-wideband (UWB) monopole antenna, transforming into a compact band-notch (3.15–4.3 GHz rejecting the Wi-Max and the C-Band) multiple-input multiple-output (MIMO) antenna is described in this paper. The diversity layout is designed within a compact size of 39 (l) × 18 (W) mm2. Due to the opposite orientation of the two radiators in the diversity configuration and the use of a rectangular parasitic strip near the feed lines, high and wideband isolation (of >20 dB) is attained over the entire UWB spectrum. The proposed layout depicts a stable omnidirectional radiation pattern and a maximal gain of 1.82 dB. The envelope correlation coefficient (ECC) is found to be below 0.18 for the entire UWB spectrum. Empirical verifications in terms of vital diversity parameters and analogy with competing layouts strengthen the candidature of the intended MIMO layout for UWB wireless portable applications.

Efficient propagation modelling for open‐confined mixed space using a hybrid ray‐tracing/waveguide theory method

AbstractThe accurate prediction of radio wave propagation along highways plays an important role in the design of high‐speed highway communication systems. The open‐confined mixed space is a connection zone between the open space and confined tunnel along the highway. A hybrid propagation model is presented based on ray‐tracing (RT) and waveguide theory, for the efficient modelling of open‐confined mixed space. The proposed model employs RT to predict radio waves emitted by sources with arbitrary radiation patterns in open space sections, and utilises the waveguide theory approach to accelerate the prediction process in the confined tunnel sections. Both two‐ray and six‐ray RT models are included to take into account the suburban and urban environments. Numerical results are compared with simulated results generated by RT as well as experimental measurements. The validity and usefulness of the proposed model are demonstrated in an actual open‐confined mixed space environment.

Dual-Polarized Dipole Antenna with Wideband Stable Radiation Patterns Using Artificial Magnetic Conductor Reflector.

This paper presents a wideband dual-polarized dipole antenna structure operating at 1.7-3.8 GHz (76.4%). For a traditional 4G dipole antenna that covers the band 1.71-2.69 GHz, it is difficult to maintain the satisfactory impedance matching and normal stable radiation patterns within the 5G sub-6 GHz band 3.3-3.8 GHz, mainly due to the fixed antenna height no longer being a quarter-wavelength. To solve this, a connected-ring-shaped metasurface structure is proposed and deployed to operate as an artificial magnetic conductor (AMC). As a result, stable antenna radiation patterns are obtained within the whole band 1.7-3.8 GHz. For verification, this wideband dipole antenna using AMC is implemented and tested. The measured results show that the proposed antenna has an impedance bandwidth of 80.7% (1.7-4.0 GHz). It has an average measured in-band realized gain of 7.0±1.0 dBi and a stable 70±5 half power beam width (HPBW) within the 4G/5G-sub 6GHz bands 1.71-2.69 GHz and 3.3-3.8 GHz.

A Novel Dual-Band Omnidirectional Horizontally Polarised Antenna Using Slotted Ground for Wi-Fi Applications

This letter explores an innovative approach to designing a compact, dual-band, omnidirectional, horizontally polarised (OHP) patch antenna with a low profile. The antenna’s ground plane is meticulously etched with radial and arch slots to create open-circuited stubs. This design generates two circulating current loops: one beneath the circular patch and the other on the outer side of the circular patch, comprised of four circular stubs. These current loops operate in unison to produce dual-band resonance and in-phase circulating current on the ground at both resonance frequencies. The antenna’s configuration includes four circular stubs formed by printing sequential radial and bent slots beneath the patch. This arrangement generates an omnidirectional radiation pattern in the azimuth plane at the upper resonance frequency. In addition, four open circular stubs outside the patch are integrated into the ground plane cascaded to the inner four stubs to achieve resonance at the lower frequency. The complete dimensions of the proposed antenna configuration are 0.29λ0 × 0.29λ0 × 0.025λ0, with bandwidths of 2.84% and 2.77% corresponding to measured resonance frequencies of 2.457 and 5.27 GHz, respectively. The measured gains are 1.2 dBi at the lower resonance frequency and 0.8 dBi at the upper resonance frequency. Furthermore, the measured roundness of the radiation pattern remains within 1 dB at the lower frequency band and within 2.8 dB at the upper-frequency band.

Quad-port 28/38 GHz Antenna with Isolation Improvement for 5G Wireless Networks

A 28/38 GHz quad-port cross-shaped antenna printed on a 0.203 mm Roger RO4003 substrate is designed and fabricated for 5G networks. The antenna consists of a rectangular patch radiator with three triangle slots to enhance the antenna's impedance matching. The four elements are arranged in a cross-shaped layout to achieve the desired compactness of 29 mm × 24.2 mm × 0.203 mm. A thin parasitic strip is inserted between the second and fourth elements to enhance the port isolation. The designed antenna is simulated by utilizing the CST simulator. The antenna achieved S11 < -10 dB at 28 / 38 GHz, with isolation ≥ 20 dB. Furthermore, the E- and H-planes within the anechoic chamber are evaluated to validate the MIMO antenna radiation patterns and gain. The MIMO parameters are calculated, simulated, tested, and its outcomes are under the standard level which confirms the MIMO diversity feature. The ECC of the structure is < 0.001, the DG ≥ 9.95 dB. and the CCL was ≤ 0.2 bit/s/Hz across the dual working band.

Far-field pattern accuracy improvement in planar near-field measurement using infinitesimal dipole modeling

This paper discusses the challenges in accurately measuring the far-field performance of array antennas, which have become more complex and larger due to recent trends in increasing the number of elements and the antenna size. The far-field measurement method, which is a general method for measuring a radiation pattern in a far-field, is difficult to be utilized at a high frequency due to limitations in physical chamber size and difficulty in diagnosing an antenna. In order to improve these problems, a near-field measurement method is used as an alternative. Even though using a near-field measurement, the accuracy of the derived far-field pattern is reduced at low elevation angles due to zero-padding of data outside the measurement area. The integration of the near-field measurement with the source reconstruction is a promising approach to enhance the measurement limits of the far-field pattern analysis. This paper aims to extend the previous work to accurately predict the far-field radiation pattern, especially in the low elevation angles. The verification of the proposed method is performed for a standard gain horn and 4 by 4 patch array antennas, with and without beam steering.

Synthesis of Circular Antenna Arrays for Achieving Lower Side Lobe Level and Higher Directivity Using Hybrid Optimization Algorithm

Circular antenna arrays (CAAs) find extensive utility in a range of cutting-edge communication applications such as 5G networks, the Internet of Things (IoT), and advanced beamforming technologies. In the realm of antenna design, the side lobes levels (SLL) in the radiation pattern hold significant importance within communication systems. This is primarily due to its role in mitigating signal interference across the entire radiation pattern’s side lobes. In order to suppress the subsidiary lobe, achieve the required primary lobe orientation, and improve directivity, an optimization problem is used in this work. This paper introduces a method aimed at enhancing the radiation pattern of CAA by minimizing its SLL using a Hybrid Sooty Tern Naked Mole-Rat Algorithm (STNMRA). The simulation results show that the hybrid optimization method significantly reduces side lobes while maintaining reasonable directivity compared to the uniform array and other competitive metaheuristics.

A performance enhanced P- and L-band double-ridged horn antenna

With the continuous development of electromagnetic detection systems, the working frequency of radar gradually expands towards the low-frequency band such as P- and L-band, and the low-frequency horn antenna has also attracted more and more attention. Given the problems of miniaturization, lightweight and ultra-wideband design of low-frequency horn antenna, this paper presents the optimal design for the feed balun, ridge curve, back-feed cavity and sidewall of the traditional horn antenna, and proposes a performance-enhanced double-ridged horn antenna covering 0.21-2.3 GHz. In the entire working band, the antenna has stable radiation patterns and good port-matching characteristics; its VSWR is less than 2 and the main lobes of patterns do not split or deteriorate. The proposed horn antenna can be used as a standard calibration or measurement antenna in antenna or material measurement systems.

Analysis of the far-field radiation pattern by a current loop in hyperbolic material

In this article, we investigate the radiations from a current loop in hyperbolic materials. To encounter the arbitrary orientation of the loop, the results are presented when the loop axis is aligned parallel and perpendicular to the optic axis. Closed-form expressions as well as numerical results are presented for both ordinary and extraordinary waves. The results indicate a strong dependence on the size of the loop, in contrast to the case of uniaxial dielectric materials. When the loop axis is parallel to the optic axis, the pattern is quite similar to that of uniaxial dielectric materials; however, a significant change in the pattern is observed when the optic axis turns perpendicular to the loop axis. The results show a significant role of the size of the loop in the hyperbolic material as compared to the uniaxial dielectric material.

Coplanar waveguide fed inverted slot hybrid square ring antenna

ABSTRACT This paper presents a compact coplanar waveguide (CPW) fed inverted T slot loaded hybrid square ring antenna for Amateur radio (HAM) application. The CPW feed line is configured with unique characteristics: lower radiation leakage, wider bandwidth, and less dispersion than microstrip lines. The antenna is low-profile and inexpensive. The antenna design occurs in High-Frequency Structure Simulator (HFSS) simulation software and attains a S11 of −10 dB. The CPW-fed hybrid square ring antenna is considered in this research, and the antenna is embedded with inverted T slots. The antenna is constructed using a Flame Retardant 4 (FR4) substrate with a thickness of 1.4 mm and tangent losses of 0.019. The key parameters of gain, radiation pattern (RP), voltage standing wave ratio (VSWR), S11, and surface current (SC) are examined. The S11 of the designed antenna is −16.07 dB, VSWR is 1.37, and the gain is 3.6 under the operating frequency range of 2.45 GHz, and the designed antenna is suitable for HAM radio applications. The radiation pattern was analysed for the E and H planes under both the measured and the simulation scenarios. The simulation results are obtained via the HFSS platform, and the fabricated measurements are in accordance with each other.

On the accuracy of a fast time resolution inversion method for the detection of different radiation patterns in fusion reactors

On the accuracy of a fast time resolution inversion method for the detection of different radiation patterns in fusion reactors

Design and analysis of a microstrip antenna for superior 5G communication performance

The continuous advancement in communication systems is propelled by the growing demand for fifth-generation (5G) technology, aiming to meet the growing demands of systems that are small in size, operate at high speeds, and have a wide bandwidth. In order to address these requirements, innovative and highly efficient antenna configurations are of paramount importance. This article introduces a microstrip antenna that has been meticulously designed for optimal performance 5G systems. Optimized for 5G communication systems, the research focuses on the design and simulation of microstrip patch antennas which is shaped like butterfly, resonating at a frequency of 50.5 GHz. A Rogers RT5880 (lossy) substrate with a dielectric constant of 2.2 was employed in the antenna design. The dimensions of the proposed antennas were 6 × 6.5 × 0.787 mm³, which resulted in a geometric configuration resembling a butterfly. A comprehensive performance assessment involves exhaustive simulations using the CST Studio Suite application suite. In order to optimize critical parameters such as the Voltage Standing Wave Ratio (VSWR), reflected power, gain, frequency range (BW), and radiation pattern, the dimensions were meticulously adjusted. Significantly, the antenna operating at 50.5 GHz demonstrated a gain of 6.8 dB, in addition to a broad bandwidth of 5.364 GHz and an outstanding VSWR of 1.0131. The outcomes successfully underscore the outstanding performance exhibited by the butterfly-shaped design, thereby establishing its suitability for implementation in 5G networks.

Folded Narrow-Band and Wide-Band Monopole Antennas with In-Plane and Vertical Grounds for Wireless Sensor Nodes in Smart Home IoT Applications

This article presents two monopole antennas with an endfire radiation pattern in the UHF band that can be installed on dry walls or metallic cabinets as a part of wireless sensor nodes, making them a suitable choice for smart home applications, such as the wireless remote control of house appliances. Two different antennas are proposed to cover the RFID bands of North America (902–928 MHz) and worldwide (860–960 MHz). The antennas have wide horizontal radiation patterns that provide great reading coverage in their communication with a base station placed at a certain distance from the antennas. The structures have two ground planes, one in-plane and the other vertical. The vertical ground helps the antenna to have a directive radiation and also makes it easily installed on walls. The antenna feeding line lies over the vertical ground substrate. The maximum dimensions of the narrow-band antenna are L × W = 0.3λ × 0.14λ, and those for the wide-band antenna are L × W = 0.39λ × 0.14λ. The measured results show that the bandwidth of the proposed antennas for the North America and worldwide RFID bands are from 902 MHz to 939 MHz and 822 MHz to 961 MHz, with maximum gains of 4.2 dBi and 4.9 dBi, respectively.

A Compact C-Band Multiple-Input Multiple-Output Circular Microstrip Patch Antenna Array with Octagonal Slotted Ground Plane and Neutralization Line for Improved Port Isolation in 5G Handheld Devices

In this paper, an eight-port antenna array is presented for 5G handheld terminals to support multiple-input multiple-output (MIMO) operations. The reported design involves three layers: the top contains eight circular microstrip feed elements; the middle is a low-cost FR-4 substrate, and the bottom layer is a ground plane with four etched octagonal slots. Each resonating element is fed by 50-ohm sub-miniature connectors. To mitigate the detrimental effects of mutual coupling of ports and enhance overall isolation between the adjacent microstrip-fed circular patch elements, a neutralization line is strategically implemented between the feed lines of the antenna array. The design configuration involves two elements at each vertex of the printed circuit board (PCB). The overall dimensions of the PCB are 150 × 75 mm2. Each slot and its corresponding radiating elements exhibit linear dual polarization and diverse radiation patterns. The proposed antenna design achieves the required operating bandwidth of more than 1000 MHz spanning from 3 to 4.2 GHz, effectively covering all the upper C-band frequency range of 3.3 GHz to 4.2 GHz allocated for 5G n77 and n78 frequency range 1 (FR1). Required port isolation and lower envelop correlation coefficient (ECC) are achieved for the band of interest. The proposed design gives a peak gain of up to 4 dB for the said band. In addition to these results, degradation in the performance of the antenna array is also investigated during different operating modes of the handheld device. Measured results from the fabricated unit cell and whole array also have a good match with simulated results. On the whole, the proposed antenna possesses the potential to be used in 5G and the open radio access network (ORAN) compliant handheld devices.

Design, Simulation and Analysis of Circular and Elliptical Antennas for 5G Applications

This research examines the design and simulation of both circular and elliptical microstrip antennas tailored for use in 5G technology, utilizing Ansoft HFSS software. The study assesses these antennas on parameters such as bandwidth, gain, and radiation patterns, aiming to meet the complex frequency demands of 5G networks. The findings suggest that circular antennas provide consistent omnidirectional coverage, whereas elliptical antennas excel in targeted coverage, essential for effective 5G communications. Moreover, elliptical antennas demonstrate significant benefits in point-to-point communications through adjustable radiation patterns. The paper offers insights into refining these antenna designs to cater to diverse 5G networking needs and proposes specific design changes to enhance their performance.

Slot-loaded Dual-Band Microstrip Patch Antenna for 5G and WLAN/WiMAX Wireless Applications

Objectives: This study introduces a dual-band rectangular microstrip patch antenna with a slot-loaded, specifically designed for 5G and WLAN/WiMAX applications. Method: The antenna is mounted on a substrate material of Rogers AD255C material having εr of 2.55 and a thickness of 1.56 mm. Three slots are etched on the conventional rectangular microstrip patch antenna. A 50-ohm microstrip line powers the antenna. The antenna that has been suggested is created and simulated using CST Studio Suite 2020. Findings: Based on numerical simulation, the proposed antenna functions at 3.5 GHz and 5.8 GHz, suitable for 5G and WLAN/WiMAX wireless technologies. The antenna offers measured return loss (S11) of -22.10 dB and -22.9 dB and a Gain of 4.43 dBi and 4.62 dBi at 3.5 GHz and 5.8 GHz, respectively. The radiation patterns are linear and broadside. Novelty: This article aims to create a smaller planer dual-band antenna that integrates WLAN/WiMAX and 5G communication standards into a single device. Keywords: Dual-band, 5G, WLAN, WiMAX, Microstrip patch antenna

Chiral and directional optical emission from a dipole source coupled to a helical plasmonic antenna

Plasmonic antennas with helical geometry can convert linearly polarized dipole radiation into purely circularly polarized far-fields, and vice versa. Besides large Purcell enhancements, they possess a wide tunability due to the geometry dependence of their resonant modes. Here, the coupling of a dipole emitter embedded in a thin film to plasmonic single and double helices is numerically studied. Using a higher-order finite element method (FEM), the wavelength dependent Purcell enhancement of a dipole with different positions and orientations is calculated and the far-fields with respect to their chirality and radiation patterns are analyzed. Both single and double helices demonstrate highly directional and circularly polarized far-fields for resonant excitation but with significantly improved directional radiation for the case of double helices.