Circular Monopole Antenna Research Articles

A Novel FSS Loaded Circular Slot Monopole Antenna for Microwave Breast Imaging Application

Breast cancer continues to be a major contributor to women's global mortality rates, emphasizing the need to explore alternative and supplementary early-stage detection techniques. This study delves into a circular slot monopole ultra-wideband (UWB) antenna equipped with a frequency-selective surface (CSMA-FSS) for early detection microwave imaging applications. To expand the impedance bandwidth of the traditional circular monopole antenna, a circular slit is introduced on a monopole structure. Additionally, a 10 × 10 unit cell FSS structure is integrated into the antenna as a far-field reflecting plane to enhance gain characteristics. The antenna, crafted with dimensions of 50 × 50 × 1.6 mm³ and a 1.6 mm thick FR4 substrate, operates across the ultra-wideband frequency spectrum, spanning from 3.1 GHz to 12 GHz, while consistently maintaining a reflection coefficient (S 11) value of – 10 dB or lower. Notably, the antenna showcases a gain of over 5 dBi across the entire 3.1 GHz to 12 GHz frequency range. The suggested antenna is ideal for microwave imaging applications due to its broad impedance bandwidth, impressive gain, and excellent directivity. Furthermore, it maintains a relatively uniform group delay, with a deviation of ±0.5 ns throughout the UWB band. In the time domain characteristics, the antenna exhibits excellent pulse handling capabilities and strong signal correlation, featuring an S 21 value of less than – 25 dB. The characteristics, observed in both the time and frequency domains, suggest that the proposed antenna holds significant potential for substantially enhancing breast cancer imaging system.

Frequency Reconfigurable Circular Monopole Antenna with Key Shaped Ground Stub

Frequency Reconfigurable Circular Monopole Antenna with Key Shaped Ground Stub

Design of a compact sigma slotted dual-mode UWB antenna for wireless body area network applications

Abstract This article presents the design of a novel sigma slotted circular monopole antenna for wireless body area network applications. The design is proceeded with a sigma-shaped slot etched on the circular radiator with Rogers 4003C substrate. The size of the proposed antenna is 30 × 30 × 1 mm3. With partial ground plane, the bandwidth characteristics of the antenna have been enhanced. The designed antenna covers 2–10 GHz of the ultra wideband, thereby providing more than 106% bandwidth. The antenna exhibits high gain values of 1.95, 3.23, 3.46, and 5.95 dB at 2.45, 3.45, 5.8, and 9.5 GHz, respectively. The proposed design operates on off-body mode at 2.45 GHz and on-body mode at 5.8 GHz, thus acting as a dual-mode antenna. To ensure the health and safety measure, specific absorption rate analysis was done for both low and high values of input power and also with Cartesian and cylindrical human arm models. Bending analysis was also done. The time domain parameter group delay was also analyzed for the proposed antenna for on- and off-body scenarios. The prototype was fabricated, and validation of simulation results was done for free space and on-body scenarios.

3-D-Printed Dual-Band Rectenna System for Green IoT Application

This paper describes the novel fully 3D-printed dual-band RF energy harvester suitable for wireless sensor network green IoT applications. The proposed energy harvesting system is composed of a dual-band circular omnidirectional monopole antenna array with a T-junction power divider, RF rectifier, and an impedance matching network. The circular monopole antenna array is conformed to a cylindrical substrate to achieve the compact system. The Villard multiplier-based rectifier has been used for the conversion of RF signal to DC voltage. The presented rectenna is fabricated using a 3D printable, biodegradable, conformal and an economical substrate. The test is performed in an RF ambient environment. The manufactured configuration obtained conversion efficiencies of 67.29% with output voltage of 1.39 V and 42.16% with output voltage of 1.1 V at 0 dBm RF input power in 2.4 GHz and 5.2 GHz frequency bands respectively. The proposed configuration’s simulated and measured results are in concordance with each other. The study emphasizes the potential of 3D-printed rectenna in terms of cost-effective prototyping.

Characteristic-Mode-Analysis-Based Compact Vase-Shaped Two-Element UWB MIMO Antenna Using a Unique DGS for Wireless Communication

The modern electronic device antenna poses challenges regarding broader bandwidth and isolation due to its multiple features and seamless user experience. A compact vase-shaped two-port ultrawideband (UWB) antenna is presented in this work. A circular monopole antenna is modified by embedding the multiple curved segments onto the radiator and rectangular slotted ground plane to develop impedance matching in the broader bandwidth from 4 to 12.1 GHz. The UWB monopole antenna is recreated horizontally with a separation of less than a quarter wavelength of 0.13 λ (λ computed at 4 GHz) to create a UWB multiple input and multiple output (MIMO) antenna with a geometry of 20 × 29 × 1.6 mm3. The isolation in the UWB MIMO antenna is enhanced by inserting an inverted pendulum-shaped parasitic element on the ground plane. This modified ground plane acts as a decoupling structure and provides isolation below 21 dB across the 5–13.5 GHz operating frequency. The proposed UWB MIMO antenna’s significant modes and their contribution to antenna radiation are analyzed by characteristic mode analysis. Further, the proposed antenna is investigated for MIMO diversity features, and its values are found to be ECC < 0.002, DG ≈ 10 dB, TARC < −10 dB, CCL < 0.3 bps/Hz, and MEG < −3 dB. The proposed antenna’s time domain characteristics in different antenna orientations show a group delay of less than 1 ns and a fidelity factor larger than 0.9.

Notch-band eliminator wideband CSRR loaded monopole fractal antenna for ISM and PCS communications

PurposeThis paper aims to present a low-cost, edge-fed, windmill-shaped, notch-band eliminator, circular monopole antenna which is practically loaded with a complementary split ring resonator (CSRR) in the middle of the radiating conductor and also uses a partial ground to obtain wide-band performance.Design/methodology/approachTo compensate for the reduced value of gain and reflection coefficient because of the full (complete) ground plane at the bottom of the substrate, the antenna is further loaded with a partial ground and a CSRR. The reduction in the length of ground near the feed line improves the impedance bandwidth, and introduced CSRR results in improved gain with an additional resonance spike. This results in a peak gain 3.895dBi at the designed frequency 2.45 GHz. The extending of three arms in the circular patch not only led to an increase of peak gain by 4.044dBi but also eliminated the notch band and improved the fractional bandwidth 1.65–2.92 GHz.FindingsThe work reports a –10dB bandwidth from 1.63 GHz to 2.91 GHz, which covers traditional coverage applications and new specific uses applications such as narrow LTE bands for future internet of things (NB-IoT) machine-to-machine communications 1.8/1.9/2.1/2.3/2.5/2.6 GHz, industry, automation and business-critical cases (2.1/2.3/2.6 GHz), industrial, society and medical applications such as Wi-MAX (3.5 GHz), Wi-Fi3 (2.45 GHz), GSM (1.9 GHz), public safety band, Bluetooth (2.40–2.485 GHz), Zigbee (2.40–2.48Ghz), industrial scientific medical (ISM) band (2.4–2.5 GHz), WCDMA (1.9, 2.1 GHz), 3 G (2.1 GHz), 4 G LTE (2.1–2.5 GHz) and other personal communication services applications. The estimated RLC electrical equivalent circuit is also presented at the end.Practical implicationsBecause of full coverage of Bluetooth, Zigbee, WiFi3 and ISM band, the proposed fabricated antenna is suitable for low power, low data rate and wireless/wired short-range IoT-enabled medical applications.Originality/valueThe antenna is fabricated on a piece (66.4 mm × 66.4 mm × 1.6 mm) of low-cost low profile FR-4 epoxy substrate (0.54 λg × 0.54 λg) with a dielectric constant of 4.4, a loss tangent of 0.02 and a thickness of 1.6 mm. The antenna reflection coefficient, impedance and VSWR are tested on the Keysight technology (N9917A) vector network analyzer, and the radiation pattern is measured in an anechoic chamber.

Wideband Quad-Polarization-Reconfigurable Bidirectional Antenna With a Simple Wideband Switchable Feeding Network

This paper presents a wideband quad-polarization-reconfigurable bidirectional antenna using a simple wideband switchable feeding network. By cutting a symmetrical fractal slot on the ground, a wideband dual-polarized differential bidirectional circular monopole antenna with high isolation is realized. To achieve reconfigurable quad-polarization diversity, the bidirectional circular monopole antenna is fed by a wideband switchable feeding network, which provides four output states by only using six PIN diodes. For verification, a prototype operating at 1.85 GHz is designed and fabricated. For the two linear polarization (LP) states, the measured 10-dB bandwidths are 28.4% and 25.3%, while the measured peak gains are 4.2 dBi and 3.1 dBi, respectively. For the two circular polarization (CP) states, the measured bandwidths with 10-dB return loss and 3-dB axial ratio (AR) are 26.3% and 17.4%, respectively. The measured peak gains are 2.8 dBi and 2.4 dBi, respectively.

A Novel Compact Ultra-Wideband Frequency-Selective Surface-Based Antenna for Gain Enhancement Applications

This article presents a compact ultra-wideband (UWB) circular monopole antenna with a frequency-selective surface (FSS) for gain enhancement. The proposed antenna has a circular patch with circular cuts at the edges and is excited by a microstrip feed. The bottom plane is truncated and further modified by two triangular cuts at the sides and one rectangular cut in the middle to improve the radiation characteristics of the UWB antenna. The antenna is designed on an FR-4 substrate with a thickness of 1.6 mm, a relative permittivity of 4.3, and planner dimensions of 30 mm × 30 mm. To improve the proposed antenna’s gain, an FSS is designed that consists of periodic unit cells of metal printed on the upper layer of an FR-4 substrate with dimensions of 0.11λ × 0.11λ at the lowest operating frequency of 3.3 GHz. The FSS shows a very low transmission coefficient and linearly reducing reflection phase with increasing frequency over a frequency range of 3.3–10.8 GHz. The gain of the proposed antenna is increased from 3 dB to 8.1 dB at 9 GHz by placing the antenna on the FSS. Moreover, the prototype of the proposed antenna is fabricated, and the experimental results are measured, which show close agreements with simulated results. The FSS-based antenna has directional radiation patterns, making it a potential candidate for ground-penetrating radar and UWB applications.

Design of Compact 2 × 2 Mimo Antenna for 5G Wireless Application

In this paper, a compact 2 X 2 MIMO antenna is proposed for 5G wireless applications. The proposed 2 X 2 MIMO antenna is designed using four compact circular monopole antennas which are optimized to operate from 3.6 to 57.7 GHz. The antenna structure consists of four orthogonal antenna elements of size 21 mm × 29 mm, which are spaced 1mm apart from each other. The antenna and the defective ground plane are placed on the same side of the substrate. It is demonstrated that MIMO system with 4- antennas produce very good isolation (>-20 dB) without using any additional isolating or decoupling techniques and antenna efficiency is also high. The antenna is simulated using CST Microwave Studio. The simulation results of the proposed MIMO antenna gives good radiation efficiency, Envelope Correlation Coefficient (ECC), improved bandwidth of 54.1 GHz, and optimum radiation characteristics. The proposed compact 2 X 2 MIMO antenna is suitable to operate under 5G wireless applications from 3.6 to 57.7 GHz. The applications of the proposed antenna also include broadcasting satellites, Modern radars, a 5GHz Wi-Fi channel, TV broadcasting satellites and microwave devices

A circular monopole antenna for bandwidth enhancement using cylinder slots with triple band notch characteristics

SummaryThis article introduces a super wideband along with three notch bands circular patch monopole antenna. The design structure is applicable for microwave and high‐speed wireless devices (2.19 to 25 GHz). In order to create a broad band, a ring dimension circular patch is used. To generate three notch bands, six symmetrical tiny cylinder stubs are introduced on the ground. These notch band frequencies can eliminate unwanted interference from various wireless frequencies, which mainly cover three notch bands: 5.5–7.3, 12.05–14.46, and 17.71–19.5 GHz. The steady radiation, super bandwidth, and stable gain properties expand when the ring patch and line feed are combined. It is excellent for many UWB applications because of its compact size (39 × 29 mm 2) and large bandwidth (166.97% fractional bandwidth). This model employs various size reduction and matching approaches to get a better response. The mechanisms of these structures are identified, and overall performance is compared with parametric analysis, tables, and figure.

Textile monopole sensors for breast cancer detection

This paper presents two flexible monopole antennas implemented on cotton substrate as sensors designed for radar-based microwave imaging and particularly breast imaging systems. The flexible antennas are basic building block of a radar-based microwave imaging system that could be integrated in clothes. Thus, these low-cost textile sensors could be used by women for self-monitoring and early breast cancer detection at an affordable price. The ultra-wideband fully textile sensors are designed as rectangular and circular monopole antennas. Both sensors have an impedance bandwidth le − 10 dB from 2.2 to 8 GHz with an overall footprint of 50 × 50 mm2. Simulations for antenna in proximity to breast model with and without tumor as well as bending capacity are performed. The simulations are complemented with fabrication of a breast phantom and a tumor sample with parameters that mimic these of the human breast’s healthy and malignant tissue. Measurements are compared to simulation results as well as the performance of antenna before and after subjected to washing. Finally, the specific absorption rate is also calculated and measured to ensure safety for on-body deployment. The proposed work demonstrates the potential to develop wearable microwave imaging system using fully textile antennas.

An Ultra-Compact 28 GHz Arc-Shaped Millimeter-Wave Antenna for 5G Application.

The 5th generation (5G) network was planned to provide a fast, stable, and future-proof mobile communication network to existing society. This research presents a highly compact arc shape structure antenna resonating at 28 GHz for prospective millimeter-wave purposes in the 5G frequency spectrum. The circular monopole antenna is designed with a radius of 1.3 mm. An elliptical slot on the radiating plane aids in achieving an enhanced bandwidth resonating at the frequency of 28 GHz. Including an elliptical slot creates new resonance and helps improve the bandwidth. The antenna has an ultra-compact dimension of 5 × 3 × 1.6 mm3, which corresponds to an electrical length of 0.46λ × 0.28λ × 0.14λ, where λ is free space wavelength at the resonant frequency. The projected antenna has an impedance bandwidth of 15.73 % (25.83-30.24 GHz). The antenna has a good radiation efficiency of 89%, and the average gain is almost 4 dB over the entire impedance bandwidth. The simulated and experimental S11 findings are in good agreement.

Additively Manufactured and Liquid Metal-Sprayed Rectenna for Energy-Harvesting Application

This research demonstrates the additively manufactured dual-band radio-frequency (RF) energy harvester for green Internet of Things (IoT) applications. The proposed energy-harvesting system consists of a dual-band circular monopole antenna (CMA) array, an impedance transformer, and a RF rectifier. The CMA array is printed on the circular substrate having a radius of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.007\lambda _{g}^{2}$ </tex-math></inline-formula> to achieve a compact size. The single-stage Villard rectifier converts the RF signal to dc voltage and the impedance transformer matches the impedance between the antenna and the rectifier. The proposed rectenna is 3-D printed on a biodegradable polylactic acid (PLA) substrate using fused deposition modeling (FDM) of 3-D printing. The experimental verification is carried out in RF ambient environment using a horn antenna and RF signal generator. The fabricated configuration offers conversion efficiencies of 72.2% and 51.21% at 2.4 and 5.2 GHz, respectively. The simulation and test results of the proposed configurations are in good agreement. The designed energy harvester would be a suitable source for low-power wireless sensor network-based green IoT applications.

Metamaterial‐based highly isolated MIMO antenna system for 5G smartphone application

SummaryA two‐port multiple‐input‐multiple‐output (MIMO) antenna system operating in the mm‐wave band for 5G applications is presented. The two elements of MIMO structure are separated from each other by 19 mm (1.9 ) and excited by microstrip feed. The MIMO elements are circular patches with round cuts at the edges to improve impedance bandwidth. Quadrilateral slot in the ground plane is designed to improve the radiation characteristics of the radiating element having size 18 0.8 mm3. The MIMO design is simulated through CST. The proposed antenna works in 27–29 GHz range, providing a potential bandwidth of 2 GHz. Furthermore a gain is improved from 8.2 to 8.75 dB and efficiency increase from 85% to 88% and high isolation of 64 dB is achieved by placing 4‐elements of metamaterial with size 4.5 18 mm2 in the middle of two circular monopole antennas. The metamaterial gives us a band stop response and act as decoupler and enhance the isolation to reduce mutual coupling. By analyzing the radiation characteristics of the proposed design, in term of reflection coefficient, surface currents, reduced mutual coupling, suitable gain, envelope correlation coefficient (ECC), diversity gain (DG) and radiation pattern, the recommended antenna can be considered a good candidate for 5G applications.

Circular slot antenna for triband application

We recommend a circular monopole antenna (CMPA) with a central feed to operate in three bands. The antenna is circular and has an 8cm diameter. The suggested antennas' resonance frequency ranges are 2.43 GHz, 5.24 GHz, and 9.61 GHz. The planned CMPA is made up of two circle-shaped slots cut into the radiating patch. The whole structure is supplied via a microstrip feed line and analysed using CST Studio's electromagnetic simulator, which is based on finite integral technique (FIT). To check the structure, the return loss, radiation pattern, voltage standing wave ratio (VSWR), and gain are all examined. The structure's ideal dimensions are determined using a parametric study of three factors: feed position, feed breadth, and ground size. The proposed CMPA is capable of operating in several bands and has good matching impedance in all of them.

Circular shape monopole antenna with modified ground plane proclaiming SWB characteristics

Abstract Modern communication systems require an antenna with miniaturized size and large bandwidth with high data rate. In this article, a circular monopole antenna is presented with hexagonal patch on both sides of microstrip feedline and an I- shaped rectangular slot etched at the center of feedline to provide impedance matching. The modified loaded ground reduces the coupling between ground plane and radiation patch. This antenna has compact dimension of 30 mm × 25 mm with electrical size of 0.25λ × 0.20λ. This antenna has been designed and simulated in HFSS commercial software and fabricated on FR4 substrate of thickness 1.6 mm with relative permittivity 4.4, loss tangent of 0.02. The experimental results are compared with simulated one, which are in close agreement. It attains a frequency band ranging from 2.4 to 56.6 GHz with reflection coefficient &lt;−10, percentage bandwidth of 183.72%, Bandwidth Ratio (BR) 23.58:1, and Bandwidth Dimension Ratio (BDR) of 3674.40. The peak gain and radiation efficiency of this antenna is 12.77 dBi and 98.82% at 45.84 and 5.6 GHz respectively. Time domain analysis has been done, which proclaims that the proposed antenna has SWB characteristics. It may be useful for high data rate transmission, medical imaging, and other SWB applications.

A UHF/UWB Monopole Antenna Design Process Integrated in an RFID Reader Board

This paper presents a new circular monopole antenna with triple-band characteristics that can operate in both ultra-high frequency (UHF) and ultra-wideband (UWB) and can be integrated into a radio-frequency identification (RFID) system reader board. The antenna was built with a patch and a coplanar waveguide (CPW) feed microstrip line to meet the UHF/UWB bandwidth requirements for RFID applications. The designed antenna has a size of 70 mm × 60 mm × 0.8 mm. CST Microwave Studio simulations were used to validate the proposed antenna, which had a maximum gain of 4.8 dBi. Furthermore, the designed antenna had a radiation pattern that spanned the full working band. To interact with RFID tags, the antenna was built and installed into the RFID reader board. The simulation and measurement findings showed good agreement. Experiments indicated that the UHF-RFID performance of the monopole antenna was comparable to that of existing commercial solutions.

A circular monopole antenna with uniquely packed quad T-shaped strips for WLAN/WiMAX application

Abstract This paper presents a circular monopole antenna with uniquely packed quad T-shaped strips etched on FR4 epoxy substrate having material permittivity 4.4, loss tangent 0.02, and thickness 1.6 mm. The 3.5 GHz band is achieved through this arrangement, which has return loss less than −10 dB while maintaining VSWR &lt;2. It provides a peak gain of 2.65 dBi at 3.5 GHz and average gain of 2.52 dBi in the entire operating frequency band. The radiation pattern is almost omnidirectional in E plane and bidirectional in H plane. The proposed antenna has a compact size of 41.25 mm × 30.55 mm. The simulated results of S11 parameters, gain, VSWR, radiation pattern, and efficiency are studied and verified with the measured results of fabricated antenna as well as its equivalent lumped circuit model. Investigation shows that the proposed antenna can be employed for WLAN/WiMAX applications efficiently.

Printed monopole antenna design with CPW fed for ultra wideband application

A circular monopole antenna fed by co-planar waveguide(CPW) for ultra wideband application is described in this article. The usage of a co-planar ground plane help to increase bandwidth for a frequency range 5G frequency spectrum’s mid band. The proposed antenna is designed to operate from 4.8GHz to 14.10GHz. With this proposed antenna, a suitable omnidirectional radiation pattern can be created. Comparison of fractional bandwidth value for various gap between the ground plane and the patch for satisfying the criteria for UWB has been analysed here.

MEMS-based reconfigurable and flexible antenna for body-centric wearable applications

The current study presents an MEMS switche-based frequency reconfigurable antenna for conformal and wearable applications. This is a circular ring-shaped monopole antenna loaded with spokes attached to the circular ring and fed by co-planar waveguide feeding (CPW). The antenna is designed on the flexible Liquid crystal polymer substrate material with 40 × 28 × 0.1 mm3. The reconfigurability of the antenna was achieved by placing RF MEMS SP4 T (ADGM 1304) switches. The antenna has a dual-band with reconfigurability at 2.5 GHz (2.12–2.9 GHz) and 5.4 GHz (4.5–5.8 GHz). The measured results demonstrate the antenna operates at 1.73–3.2 GHz and 4.54–6.3 GHz with resonating frequencies of 2.5 and 5.6 GHz. When placed on the human body, the gain of the antenna variesg from 5.32 to 8.38 dBi for different reconfigurable conditions. SAR analysis results in between 0.15 W/Kg and 1.37 W/Kg for different switching conditions, and the simulation results match with the measurements.