Return Loss Performance Research Articles

Performance-constrained multi-objective optimization of antennas for miniaturization design

The miniaturization of antennas is crucial as it improves the integration of wireless communication system. In order to achieve miniaturization of antennas, a performance-constrained multi-objective optimization method (PCMOM) considering the size and return loss is proposed. In the PCMOM method, an optimization strategy based on a multi-port network model is introduced, enabling the formation of antennas with various structures. Furthermore, we integrate the constraint of return loss performance into the non-dominated sorting genetic algorithm II (NSGA-II), eliminating solutions that do not meet performance requirements. Three pixel antennas are designed using the PCMOM method and two of them are fabricated. Experimental results demonstrate that the proposed PCMOM method can effectively address the complex trade-off issues in antenna miniaturization design.

Flexible Textile Antennas for 5G Using Eco‐Friendly Water‐Based Solution and Scalable Printing Processes

AbstractFlexible textile antennas are important for wireless communication within the expansion of 5G and the Internet of Things (IoT), as it allows for their integration in daily life objects. However, achieving these functionalities in textiles is challenging because of limitations in the electronic performance, flexibility with scalable fabrication process. This paper presents two flexible textile antennas for wearable and non‐ wearable devices compatible with 5G technology created by printing highly conductive silver nanoparticle inks. Two textile substrates are explored, as the dielectric component, a 3D polyester, and a natural origin fabric, burel. The processes used are cost‐effective and scalable, with the antennas designed to operate at 3–3.5 GHz, maintaining their return loss performance even under bending deformation and washing cycles. By transferring the optimized devices into clothes and wall covering, a detailed analysis with experimental measurements of the textile‐based antenna for different operation scenarios is introduced. The work highlights the suitability of these antennas for wearable applications and their alignment with green wireless technologies, contributing to the advancement of sustainable wireless communication systems.

COMPUTATIONAL FRAMEWORK FOR HUMAN DETECTION THROUGH IMPROVED ULTRA-WIDE BAND RADAR SYSTEM

This paper presents a framework for human detection using an ultra-wideband (UWB) radar system and proposes a novel UWB radar antenna design with double-winding structures for radar applications. The proposed antenna achieves high gain and bandwidth, overcoming the shortcomings of Vivaldi antennas, which are the preferred antennas for radar applications. In the proposed novel design, winding structures are incorporated nearer to the main resonator, which suppresses harmonic distortion and enhances the radar detection process. The proposed antenna is designed to cover a frequency range from 6 GHz to 10.5 GHz. The design is analyzed for different design configurations with and without winding structures. However, the dual-side winding structure configuration achieves better performance than the single-side winding structure. The proposed design achieves a maximum bandwidth of 2.09 GHz in the dual-side winding structure configuration, which is a remarkable achievement for radar and precise locating applications. The proposed design achieves improved return loss performance greater than -10 dB in all operating frequencies and voltage standing wave ratios equal to 1 with improved gain and directivity.

Engineering planar antenna using geometry arrangements for wireless communications and satellite applications

A triple-band microstrip patch antenna designed for the IEEE 802.16e WiMAX, IEEE 802.11a WLAN, C-band downlink communications, and Ku-band radar recent applications is suggested in this article. The planned antenna operates at 2.45, 6, and 14 GHz resonant frequencies. The antenna fulfilled triple-band physical characteristics covering industrial, scientific, and medical (ISM) bands between (2.1–2.8) GHz; (5.6–6.5) GHz for wireless local area network (WLAN) or ultra-wideband (UWB) services; and 12.7–16 GHz for future two-way 5G:6G either broadcasting or mobile satellite communications. To achieve better return loss performance, parametric studies are carried out using Microwave Studio (CST MWS). The proposed antenna is designed on the FR4 as a hosting medium of total size 46 × 38 × 1.6 mm3, combined with a planar transmission line (T.L.) feed and defected ground structure (DGS). The simulated antenna’s input reflection coefficient (S11) results and the far-field measurements show good agreement. The fabricated prototype achieves peak gain values of 2.8, 3.8, and 4.7 dBi, respectively, and bidirectional radiation characteristics. A comparative study with other recent publications is implemented to validate the consistency of the design.

Microstrip to Slot-Line-Fed Microstrip Patch Antenna with Radiation Pattern Diversity for X-Band Application

This paper proposes a planar wideband microstrip feedline to a slot-line-based patch antenna for high-frequency pattern diversity applications. The antenna consists of two adjacent rectangular patches separated by the ground slots, with a directive patch slot along the edge of the substrate. A compact common feedline-to-slot configuration is used to miniaturize the antenna. The antenna is designed in stages, starting with an in-phase feedline, followed by a slot line structure, with two radiating patches on top and a director on the side. This creates radiation diversity with directive radiation patterns. The antenna was fabricated and analyzed inside a far-field anechoic chamber. The experimental results validate the return loss, gain, and radiation performance. The measured results of the antenna within a frequency range of 8.5 to 11 GHz show good agreement with the simulation. The antenna has a maximum gain of 9.2 dBi and has the potential to be beneficial for beam steering and X-band applications due to its low profile, broad bandwidth, high gain, and good directivity.

Design of a multi‐function global navigation satellite system and 5G cellular antenna structure for automotive applications using characteristic mode analysis

AbstractThis paper illustrates a single antenna structure that simultaneously satisfies the antenna requirement for 5G cellular and global navigation satellite systems (GNSS). The antenna has a linearly polarised omnidirectional radiation for the newly defined 5G sub‐6 GHz cellular bands in the 617–5000 MHz frequency range. In contrast, a right‐hand circular polarisation (RHCP) with a hemispherical radiation pattern at the GNSS L1 has a frequency range of 1559–1606 MHz. This multi‐function antenna would provide a simplified product design and better space utilisation, particularly suitable for flat antenna modules and automotive. The primary concept involves employing a planar inverted F antenna structure to generate radiation modes for cellular bands and incorporate U‐slot on the top plate to generate the GNSS radiation modes. The design methodology utilises the characteristic mode analysis tool to tune the desired radiation characteristic mode at the intended frequency range for each function. The antenna was fabricated, and the performance was evaluated on a 1‐m ground plane. The GNSS RHCP gain measures 5 dBc at boresight, with an axial ratio below 2 dB across the L1 bands, while the cellular gain maintains an excellent return loss and omnidirectional radiation pattern performance across the cellular bands.

Ultra-wide band antipodal Vivaldi antenna design using target detection algorithm for detection application

This work presents a technique for detecting targets between two walls using ultra-wide band (UWB) modified antipodal Vivaldi antenna (MAVA). The detection system works on principle of time domain reflectrometry (TDR) using through wall imaging (TWI). This technique utilized a vector network analyzer (VNA) to produced short and small pluses to irradiate through an antenna array system onto the wall under study. The purposed detection system operated in UWB frequency spectrum (3.1 GHz to 10.6 GHz). Furthermore, an algorithm for hidden target detection has been developed. The results of the simulation of the designed antenna revealed a significant level of penetration, demonstrating a smart advancement in detecting and imaging system, to locate hidden metallic targets with good accuracy. A signal processing technique have been employed to improve the resolution of the target image. Using computer simulation technology (CST) software, the development and optimization process of an antenna is carried out, and the parametric performance of return loss, directivity and radiation pattern is evaluated.

Dual-Band Substrate Integrated Waveguide Filters Based on Multi-Mode Resonator Overlapping Mode Control

In this paper, a multi-mode resonator (MMR) overlapping mode control technique is proposed to realize dual-band substrate-integrated waveguide (SIW) bandpass filters (BPFs). A pair of via perturbations and two kinds of slotlines are introduced to control the overlapping modes. Five resonant modes TM110 (a pair of degenerate modes), TM210 (a pair of degenerate modes) and TM020 are perturbed to realize the dual-band filters. The degenerate modes can be rearrange by the via perturbations, and the overlapping modes can be adjusted by the slotlines. Thus, two kinds of dual-band filters can be realized in a single resonant cavity. Then a two-cavity dual-band filter is proposed to realize better out-band suppression and return loss performance. The proposed two-cavity dual-band BPF is synthesized, designed, fabricated, and measured, realizing the 3-dB fractional bandwidth (FBW) of 6.1% and 7.7% at Q-band and V-band, respectively.

Dual‐band Ganesha‐shaped semi‐transparent antenna for vehicular applications

AbstractIn this paper, work on a Ganesha‐shaped semi‐transparent patch antenna is presented for its use in vehicular application. The design of the antenna is opted from a commercially available Ganesha sticker that is mostly placed on the vehicle's window panes as a symbol of an auspicious deity. The geometry of the sticker without any variation in its dimension is made to work as an antenna. The antenna is fabricated using adhesive copper tape on a glass slab backed by an AgHT‐8 transparent conducting sheet which acts as the ground plane. Microstrip inset feeding technique is used to excite the patch and its return loss performance and free space radiation pattern measurements are carried out. Measured results show promising performances that can be used in future vehicular applications and are in good comparison with that of the simulated results.

Design of a broadband frequency-tunable planar filtering power divider

ABSTRACT In order to meet the development requirements of multi-frequency and functional integration of radio frequency (RF) modules, a broadband tunable filtering power divider with center frequency is designed. A new structure is composed of open branch line, step impedance resonator, and double branch resonator. The filter response is realized by branch line and double branch resonator. The resonant frequency of the device can be adjusted flexibly by controlling the varactor diode loaded on the two resonators with external voltage. The double branch resonator can realize the broadband frequency adjustability, the step impedance resonator can improve part of the return loss performance of the device, so that the central frequency can achieve high performance in a wide tuning range. The research results show that the center frequency of the designed filtering power divider is adjustable in the range of 1.6 GHz to 2.7 GHz, the tuning bandwidth is 51.2%, the input return loss of each center point is better than 20 dB, and the isolation between output ports is better than 19 dB. The device is expected to be widely used in RF communication systems such as array antennas and transceiver components.

MULTIBAND FLEXIBLE ULTRA-WIDEBAND ANTENNA FOR WEARABLE ELECTRONICS AND BIOMEDICAL APPLICATIONS

This article proposes a flexible ultra-wideband (UWB) antenna for wearable electronics and biomedical applications. The antenna presented for this work is fabricated on a Kapton polyimide (PI) substrate, and the operating frequency ranges from 2.4 GHz to 7.1 GHz. The footprint of the proposed antenna is 35 × 45 mm with an elliptical radiating element fed by coplanar waveguide (CPW), which achieves improved impedance matching characteristics. The choice of substrate, design constraints, fabrication process, and bending test of the proposed flexible UWB antenna are explained in detail in this paper. A comparative study on the choice of substrate is performed and the Kapton PI is chosen as the substrate material, which makes the antenna less susceptible to degradation in antenna performance that arises due to bending effects. The measurement and simulated results of the fabricated antenna show a good degree of agreement. The return loss performance of the proposed antenna is greater than -10 dB in all the operating bands with improved gain and directivity. The flexible nature with multiple frequency bands of operation and good bending performance makes the proposed antenna appropriate for wearable electronic and biomedical applications.

Palm Tree Coplanar Vivaldi Antenna Array on the Same Substrate Size: Design and Performance Evaluation

This paper aims to describe the performance of the palm tree Coplanar Vivaldi Antenna Array (CVA) that was simulated from 0.25-6.25 GHz in terms of return loss and radiation pattern. Palm Tree Coplanar Vivaldi Antenna is available in four different configurations: single-element, two-element array, four-element array, and an eight-element array. We create a feeding network and radiator patch for two, four, and eight-array antennas. The simulation results demonstrate that the single-element antenna has the best return loss performance and can cover all frequency work from 0.25-6.25 GHz. In contrast, the antenna array can only cover multiband frequency. At 3 GHz, a single-element antenna has a directivity of 8.77 dBi, a sidelobe level of -2.2 dB, and a beamwidth of 63.70. In contrast, an antenna array of 8 elements has a directivity of 15.5 dBi, a sidelobe level of -12.6 dB, and a beamwidth of 80. Using the same substrate size, by configuring the Vivaldi Coplanar antenna to be an array at a frequency of 3 GHz, the 1×8 array antenna has a 6.73dBi improvement in directivity, a 10.4 dB boost in side lobe level, and a 55.70 enhanced in beamwidth performance compared to a single element. According to the simulation findings, the radiation pattern performance of the. Palm Tree CVA is greater than a single element in the same substrate size. Good directivity, SLL, and beamwidth performance make the proposed Palm Tree CVA array suitable for integration in telecommunication, radar, or cognitive radio applications.

Design of 1 × 2 MIMO Palm Tree Coplanar Vivaldi Antenna in the E-Plane with Different Patch Structure

In this paper, 1 × 2 MIMO of Palm Tree Coplanar Vivaldi Antenna is presented that simulated at 0.5–4.5 GHz. Some GPR applications require wideband antennas starting from a frequency below 1 GHz to overcome high material loss and achieve deeper penetration. However, to boost the gain, antennas are set up in MIMO and this is costly due to the large size of the antenna. When configuring MIMO antenna in the E-plane, there is occasionally uncertainty over which antenna model may provide the optimum performance in terms of return loss, mutual coupling, directivity, beam squint, beam width, and surface current using a given substrate size. However, the configuration of E-plane antenna in MIMO has an issue of mutual coupling if the distance between elements is less than 0.5λ. Furthermore, it produces grating lobes at high frequencies.We implement several types of patch structures by incorporating the truncated, tilt shape, Hlbert and Koch Fractal, Exponential slot, Wave slot, the lens with elips, and metamaterial slot to the radiator by keeping the width of the substrate and the shape of the feeder. The return loss, mutual coupling, directivity, beam squint, beamwidth, and surface current of the antenna are compared for 1 × 2 MIMO CVA. A continuous patch MIMO has a spacing of 0.458λ at 0.5 GHz, which is equivalent to its element width. From the simulation, we found that Back Cut Palm Tree (BCPT) and Horizontale Wave Structure Palm Tree (HWSPT) got the best performance of return loss and mutual scattering at low-end frequency respectively. The improvement of directivity got for Metamaterial Lens Palm Tree (MLPT) of 4.453 dBi if compared with Regular Palm Tree-Coplanar Vivaldi Antena (RPT) at 4 GHz. Elips Lens Palm Tree (ELPT) has the best beam squint performance across all frequencies of 0°. It also gots the best beamwidth at 4.5 GHz of 3.320. In addition, we incorporate the MLPT into the radar application.

High power balanced TEM horn antenna for ultra wide band radiator

AbstractA balanced transverse electromagnetic (TEM) horn type antenna is designed and developed for a 120 kV, 66 Ω high power ultra wideband (UWB) radiator. This antenna consists of a coaxial to parallel plate unzipper BALUN followed by an exponentially tapered TEM horn structure. Analysis of this antenna in time and frequency domain is performed using CST Microwave Studio. This antenna is having a power handling capacity of 1000 MW, with percentage bandwidth of 167%. This antenna has a gain of ~10 dB at 1 GHz frequency. Return loss performance of better than −10 dB is observed in 150 MHz to 1 GHz frequency range. Effective radiation of short pulses (<5 ns) with very fast rise time (300–500 ps) has been demonstrated using this high‐power antenna. Practical results at 220 MW power are presented in this article. Directional performance of this antenna is practically established through peak power patterns in horizontal and vertical plane.

Design and Fabrication of the Split Ring Resonator Shaped Two-Element MIMO Antenna with Multiple-Band Operation for WiMAX/5G/Zigbee/Wi-Fi Applications.

In this manuscript, we proposed the split ring resonator loaded multiple-input multiple-output (MIMO) antenna design for the frequency range of 1 and 25 GHz. The proposed antenna is numerically investigated and fabricated to analyze the different antenna parameters. We provided statistics on a wide range of antenna parameters for five different designs, including a simple circular patch antenna, a single-split-ring antenna, and a double-split-ring antenna. Reflectance, gain, directivity, efficiency, peak gain, and electric field distribution are all analyzed for all proposed antennas. The maximum achievable bandwidth is 5.28 GHz, and the double-split-ring resonator structure achieves this with a return loss of -20.84 dB. The radiation patterns of all the antenna with different port excitation conditions are presented to identify the behavior of the antenna radiation. We found the effect of the split-ring resonators to form radiation beams in different directions. We found the maximum and minimum half-power beam widths of 75° and 2°, respectively, among the different antenna designs. It was found that the split-ring resonator geometries in patch antenna convert wide-beam antenna radiation patterns to several narrow-beam radiation patterns. We found that each antenna's bandwidth, gain, and return loss performance significantly differs from the others. Overall, the proposed results of the antenna may apply to a wide range of communication applications, including those for Wi-Fi, WiMAX, and 5G.

Design of a Compact ISM-band Microstrip Slot Antenna for Wireless Sensor Nodes

Objective: To enhance the design and implementation of microstrip antenna for wireless Sensor Networks (WSN) in real-time applications Methods: This study uses radio communication to connect end nodes and forms a multihop self-organizing network with a dynamic topology. Also, the antenna is fabricated from low-cost FR-4 printed circuit board (PCB) material. The designed rectangular patch antenna operates in the industrial, scientific, and medical (ISM) frequency band of 2.45 GHz, and HFSS software analyzer is used to authenticate the proposed work. Findings: The designed antenna finds an extensive use in short-range wireless sensor networks, the proposed antenna reduces the return loss from 10% - 13 % and almost 15% improvement in radiation compared with K. D. Xu (2018) and E. Zhang (2020). Novelty: A novel short range, low power, and well directional microstrip patch antenna are designed to improve the wireless Sensor communication applications operating at 2.4 GHz and 5.3 GHz frequencies. The presented approach is simple to operate, cost-effective, energy-efficient, and has optimum return loss performance (please refer Table 2) when compared to the existing approaches. Keywords: Microstrip antenna; Compact; HFSS; Wireless Sensor Network; dual frequency

Empirical analysis of microstrip patch antenna for different substrate materials and shapes using aperture coupled technique

The dielectric material used as a substrate and the shapes of the patches play an important role in the performance of bandwidth, return loss, and gain of the microstrip patch antenna. This paper presents the relative study of different shapes of microstrip Patch antenna for different dielectric materials. The main application of these antennas is for satellite communication in Ku-Band. The height of the substrate plays an essential role in the enhancement of bandwidth and it is chosen 1.012mm and three substrate materials (RT Duroid (5880), Teflon, and FR4) with different dielectric constants were chosen for the performance comparison. Aperture coupling, which is again one of the promising techniques for bandwidth enhancement, is used as a feeding technique for the designs. Coupling must be taken care of while using aperture coupling, which is done by precisely optimizing the feed line dimensions, feed position, slot dimensions, and patch dimensions. The antenna performance is studied by varying the parameters like patch, feed line, and slot dimensions, the size of the substrate, and the feed line position concerning the slot. Optimization is also performed for the position of the ground layer within the substrate material and the ground plane in the middle position of the substrate is chosen for the final designs. Return loss and impedance matching were analyzed for all designs. The rectangular and circular patches are used for a comparative study, which is conducted from 12GHz to 14GHz out of which the circular patch is found to give better performance. The analysis is carried out for RT Duroid (5880) material and the bandwidth obtained in both cases is almost 3GHz. Similarly, the analysis is carried out for different dielectric materials over the frequencies of 12GHz to 14GHz in which RT Duroid and Teflon give better performance in terms of return loss and FR4 gives better performance in terms of miniaturization. The analysis is carried out for rectangular patches and the bandwidth obtained for FR4 is 1GHz whereas, for RT Duroid (5880) and Teflon, it comes out to be 3GHz. The results are depicted in various tabular and graphical formats. This study is conducted using an HFSS, an electromagnetic solver.

Investigating the S-parameter (|S<sub>11</sub>|) of CPW-fed antenna using four different dielectric substrate materials for RF multiband applications

<abstract> <p>This article aims to examine the |S<sub>11</sub>| parameter of a multiband Coplanar Waveguide (CPW)-fed antenna. The proposed square-shaped antenna-1 (Ant.1) and antenna-2 (Ant. 2) are primarily composed of three ground terminal stubs: Terminal-1 (T1), Terminal-2 (T2), and Terminal-3 (T3), all of which have an inverted L-shaped radiating patch. The proposed antennas' resonance frequencies (<italic>f<sub>r</sub></italic>) can be adjusted by the electrical dimension and length of the stub resonators, the dielectric constant (ε<italic><sub>r</sub></italic>) of substrate materials, and their appropriate thicknesses. It will have an impact on their return loss (|S<sub>11</sub>|), Impedance Bandwidth (IBW), radiation pattern, and antenna performance in terms of frequency characteristics, as demonstrated in this article. The proposed structure based on Flame-Retardant fiber glass epoxy (FR4) substrate covered a wideband frequency range from 1.5 to 3.2 GHz, (IBW = 1.7 GHz) and from 3.4 to 3.65 GHz (IBW = 0.25 GHz). The total IBW is 1.95 GHz, at S<sub>11</sub> ≤ −10 dB with three resonance frequencies of values <italic>f<sub>r1</sub></italic> = 1.75, <italic>f<sub>r2</sub></italic> = 2.65, and <italic>f<sub>r3</sub></italic> = 3.50 GHz) for triple-band applications. The results are compared with the research work reported earlier. The proposed Ant.1 ensured, dual and triple band applications whereas the proposed Ant. 2 ensured dual, triple and quad bands applications with reasonable antennas' sizes similar to the earlier reported works. Furthermore, the impacts of various substrate materials as well as different lengths of multi-stub resonators on the operating bands and resonance frequency are thoroughly explored and analyzed for these antennas.</p> </abstract>

Mutual Coupling Evaluation and Radiation Pattern Performance for Coplanar Vivaldi Antenna Array

This study has aimed to examine the mutual coupling evaluation and the radiation pattern performance of the Coplanar Vivaldi Antenna (CVA) array. Generally, the mutual coupling evaluation is determined based on the calculation of two antenna elements in the E-plane and the mutual scattering assessment of several linear and planar array configurations. The calculation is analyzed by multiplying the radiation pattern modeling of its element and the flux pointing vector. There has been a significant difference between the simulation and the modeling results of the radiation pattern element and mutual coupling of the Coplanar Vivaldi antenna. The mutual scattering has been determined in the contour plot with different array configurations in the E and in the H-plane. Coplanar Vivaldi Antenna with Exponential Corrugated Slot (CVA-ECT) has showed a better return loss and gain performance than CVA with No Slot (CVA-NS) in the E-plane, which is different in the H-plane. With the same volume size of an array, the smaller the width of the element is, the better the performance in radiation pattern than the wider ones is. The planar array shows that at 7 GHz, the 3×2 array gains up to 13.69 dB while 2×2 CVA-NS attains 8.9 dB in the same volume.

The Design of a Wideband Antenna with Notching Characteristics for Small Devices Using a Genetic Algorithm

This paper presents the design and realization of a compact printed ultra-wideband (UWB) antenna with notching characteristics for compact devices using a genetic algorithm. The antenna is capable of mitigating an adjacent sub-band ranging from 3.75 to 4.875 GHz, mainly used by many applications and standards such as WiMAX, WLAN and sub-6-GHz. The notch band functionality is achieved by etching out two symmetrical slots from the pentagonal radiating element. The simulation and measured results demonstrate that the proposed antenna overperformed compared with state-of-the-art antennas in terms of compactness with an overall size of 20 mm×15 mm×0.508 mm. Moreover, the proposed design shows a large bandwidth in the UWB region with a fractional bandwidth of 180% with respect to the center frequency of 5.25 GHz. The antenna also presents omnidirectional radiations all over the operation band and a good return loss performance.