Circular Patch Research Articles

Design and Assessment of Bio-Inspired Antennas for Mobile Communication Systems

RF front-end system in the mobile communication system consists of an antenna, filter, and amplifier section. Now a day, there is a need to reduce the size of this RF front-end system. Here the challenge is the reduction in the size of the RF front end without degrading the performance. One way to reduce the size is by reducing the size or area of the antenna. This work proposes and simulates three Bio-inspired microstrip (BIMS) antenna designs. They are flower, Butterfly, and leaf shapes presented based on the perturbation method, Gielis super formula, and modified polar transformation models, respectively. These BIMS antennas were printed on fiberglass laminate (FR4) as substrate with a dielectric constant of εr = 4.4 and a loss tangent of 0.02. The simulation results cover parameters of the antenna, such as reflection coefficients (S11), surface current density (Jsurf), and radiation patterns. They offer a maximum gain of 14 dBi, 8 dBi, and 4dBi, respectively, and their results are compared with other works. These antennas are less in size, so they occupy less area compared to conventional rectangular or circular patch antenna, which radiates in L and S bands at different frequency ranges.

Four-Port 38 GHz MIMO Antenna with High Gain and Isolation for 5G Wireless Networks

In this paper, a 38 GHz 4-port multiple-input multiple-output (MIMO) antenna with considerable isolation and gain enhancement for 5G applications is introduced. The suggested antenna element is a monopole antenna composed of a circular patch with a rectangular slot etched from it and a partial ground plane is used to extend the desired frequency to operate from 36.6 GHz to 39.5 GHz with a center frequency of 38 GHz. The high isolation is achieved by arranging the four elements orthogonally and adding four stubs to reduce mutual coupling between elements at the desired frequency bands. The gain improvement is also introduced by placing a frequency selective structure (FSS) which is designed at the same frequency bands of the antenna under the suggested MIMO antenna to act as a reflector. The proposed four-element MIMO with the FSS prototype is built and tested in order to confirm the simulated results. The suggested antenna operated from 37.2 GHz to 39.2 GHz with an isolation of less than 25 dB across the obtained frequency range. The peak gain of the antenna is enhanced from 5.5 dBi to around 10 dBi by utilizing the FSS structure; furthermore, the back radiation is enhanced. The MIMO performance is validated by extracting its parameters and comparing with the simulated results. The results extracted from the simulation and the measurement show satisfactory matching along with the target band, indicating that the proposed structure could be used for 5G communications.

A wideband and low‐profile omnidirectional circularly polarized antenna

AbstractThis article presents a wideband and low‐profile omnidirectional circularly polarized antenna. It consists of a circular slotted top patch connected with a circular ground plane by four shorting vias and eight extended curved branches. These curved branches are introduced around both the patch and the ground plane with proper angle separation, achieving a 90‐degree phase difference between the vertical and horizontal radiating parts. In this way, the wideband circularly polarized characteristic is realized. The final optimized structure is very compact, with a dimension of only 322 × π × 6 mm3 (0.372 × π × 0.07 = 0.03 λ03). Besides, the measured results agree well with the simulated ones, with a simulated/measured impedance bandwidth of 28.4/32.2% and an axial ratio bandwidth of 46.7/42.3% being obtained. And the maximum realized gain is 1.1 dBic, with a gain variation of less than 1.0 dB.

Flexible and Small Textile Antenna for UWB Wireless Body Area Network

In this paper, a miniaturized textile microstrip antenna is proposed for wireless body area networks (WBAN). The ultra-wideband (UWB) antenna used a denim substrate to reduce the surface wave losses. The monopole antenna consists of a modified circular radiation patch and an asymmetric defected ground structure, which expands impedance bandwidth (BW) and improves the radiation patterns of the antenna with a small size of 20 × 30 × 1.4 mm3. An impedance BW of 110% (2.85–9.81 GHz) frequency boundaries was observed. Based on the measured results, a peak gain of 3.28 dBi was analyzed at 6 GHz. The SAR values were calculated to observe the radiation effects, and the SAR values obtained from the simulation at 4/6/8 GHz frequencies followed the FCC guideline. Compared to typical wearable miniaturized antennas, the antenna size is reduced by 62.5%. The proposed antenna has good performance and can be integrated on a peaked cap as a wearable antenna for indoor positioning systems.

A wideband monopolar patch antenna with a high system fidelity factor for IR‐UWB application

AbstractA compact, broadband microstrip patch antenna with stable monopole‐like radiation patterns is proposed for impulse‐radio ultrawideband (IR‐UWB) positioning systems. Such the antenna consists of a circular patch with eight conductive vias placed concentrically, resulting in the and modes. Moreover, a tapered feeding probe at its center is presented to enhance the matching and excite an antiresonance mode. The compact size of is obtained by using a square ground. The measured results show that the antenna has an impedance bandwidth of 44.1% from 6 to 9.4 GHz and stable monopole‐like radiation patterns in the frequency domain. Finally, a system fidelity factor larger than 96% and a relatively stable group delay are simulated and measured in the time domain. Therefore, this antenna can be potentially useful for UWB pulse transmission with attractive features in engineering applications.

Design of a transparent and flexible broadband omnidirectional antenna using characteristic mode analysis

An optically-transparent, mechanically flexible, monopole-radiation-characteristic, broadband omnidirectional antenna is proposed in this work. The radiator layer of the sandwich-structured antenna consists of a circular central patch with 16 circular satellite patches, and the characteristic mode analysis (CMA) was used to guide the detailed design process. We first analyzed the different modes of the 3×3 circular patch array, further reduced the size of the surrounding patch to increase the required omnidirectional mode bandwidth, further reduced the cross-polarization by adjusting the distance between the four corner patch and the central patch, and finally increased the number of surrounding patches to increase the bandwidth and gain. The entire analysis and optimization process uses the CMA. The antenna was excited by a single probe, with good omnidirectionality, low cross-polarization, and broad operating bandwidth in (5-12.7) GHz, achieving 87% relative bandwidth and peak gain of 4.1 dBi. The antenna has a radius of 27 mm and a thickness of 4.5 mm. A transparent and flexible antenna sample was fabricated on a flexible polydimethylsiloxane (PDMS) substrate using electrohydrodynamic (EHD) printing technology. The optical transmittance of the horseshoe-structured metal grids fabricated by EHD was investigated, as well as the equivalent surface resistance evaluation method. The theoretical optical transmittance of the horseshoe-structured single-layer silver grid on the PDMS substrate was 81.2%, versus 80.8% measured value, with an equivalent surface resistance of roughly 5 Ω/◻. The proposed antenna was bent on a 50 mm-radius cylinder surface and retained excellent omnidirectionality.

A monopole broadband circularly polarized antenna with coupled disc and folded microstrip stub lines

A broadband circularly polarized (CP) printed monopole antenna which fed by coplanar waveguide (CPW) is proposed in the paper. The structure of the novel antenna includes a quarter circular disc radiating monopole, a coupled circular patch, and a bent L-shaped microstrip stub line. The L-shaped microstrip stub line is used to widen the impedance bandwidth and generate a horizontal component of the electromagnetic wave. The adoption of the asymmetric ground coplanar waveguide structure with the single-feed technology and the coupled circular patch, simultaneously achieve wide impedance bandwidth and wide axial ratio (AR) bandwidth. The structure parameters and the surface current of the designed antenna are analysed. The simulation and the measurement are conducted, showing good characterizations of the designed antenna. The 10-dB impedance bandwidth is 7.57 GHz, the fractional bandwidth from 6.05 to 13.62 GHz is 76.9%, the 3-dB axial ratio bandwidth is 3.01 GHz, and the fractional bandwidth from 6.05 to 9.06 GHz is 39.8%. The antenna can generate right/left hand circularly polarized waves in the direction of ± z axis. The designed antenna has wide applications in the fields of Internet of Things (IoT), broadband dual-CP communication systems and polarization diversity systems, wireless personal area network and other advanced communication systems.

Perancangan Antena Metamaterial Patch Circular Untuk Teknologi 5G Dengan CSRR Pada Frekuensi 3.5 GHz

The development of 5G technology at this time has a much faster speed, capacity and latency in accessing data compared to 4G technology. 5G technology has several components that are influential in the application of 5G technology, one of which is the antenna. Microstrip antennas are antennas that have simple materials, smaller antenna dimensions, so that production costs are cheaper, affordable and the performance of microstrip antennas is quite good. Microstrip antenna has several drawbacks, namely low gain and not wide bandwidth. In this study a circular patch microstrip antenna was designed using FR-4 material using a relative dielectric constant of 4.4, a loss tangent of 0.02 and a substrate thickness of 1.6 mm. The microstrip antenna that will be added to the groundplane section uses a metamaterial structure, namely the Complementary Split-Ring Resonator (CSRR) which operates at a frequency of 3.5 GHz. The addition of the CSRR metamaterial structure aims to increase antenna bandwidth and miniaturization. The simulation results of a microstrip antenna without CSRR can work at a frequency of 3.5 GHz with a return loss of -15.71 dB, a VSWR of 1.39, a gain of 2.121 dBi, a bandwidth of 120 MHz and the resulting radiation pattern is unidirectional. While the antenna that has been added CSRR at a frequency of 3.5 GHz has a return loss of -19.50 dB, a VSWR of 1.23, a gain of 1.454 dBi, a bandwidth of 410 MHz, the resulting radiation pattern is bidirectional and the antenna undergoes miniaturization at a groundplane width of 18%. That way the antenna using the CSRR method can increase bandwidth and miniaturization.

High-gain reconfigurable polarization antenna based on metamaterial array for Terahertz applications

This paper suggestsproposes a high-gain reconfigurable polarization antenna using a metasurface polarizaer. The metasurface polarizer is a rectangular array that consists of similar 25 unit-cell elements. Each metamaterial (MM) unit-cell element consists of a circular copper patch attached to two copper arrow-shaped strips installed at its circumference. The circular patch and two arrows are installed between a rectangular superstrate at the top and a rectangular substrate at the bottom, which is backed with a perfect electric conductor with a relative permittivity of εsub = 3.38. The MM characteristics are obtained in a wide range of frequencies from 1.4 to 2.1 THz. The metasurface polarizer array is installed at an optimized height of 25 μm under a linear polarized dipole antenna that operates at 1.81 THz with a bandwidth (BW) of 0.2 THz from 1.75 to 1.95 THz (11.05%, − 10 dB BW) and gain of 2.27 dBi. The incident-plane wave from the antenna can be converted into a reconfigurable left- or right-hand circular polarization according to the directions of the arrow of the MM unit-cell element. Moreover, the operating − 10-dB BW of the dipole antenna increases to 30.93%, and the gain is enhanced to 6.18 dBi at the same operating frequency. A reconfigurable polarization conversion for the dipole antenna can be obtained over wide 3-dB axial ratio BW from 1.45 to 1.95 THz (33.3% BW).

Surface current engineering enabled broadband monopole patch antenna with low profile

Antennas with broadband radiation and small-size are highly required in wireless communication system. The trade-off relation between bandwidth and size became a difficulty when it comes to miniaturized antenna design. A method of realizing antenna miniaturization and bandwidth enhancement at the same time is needed. Monopole antennas are the most common used one in the devices of Internet of Things, Internet of Vehicles, and wireless access points et al. In this paper, a wideband low-profile top-loaded patch monopole antenna based on surface current engineering is proposed. The topology combines a center-fed circular patch with inductive vias. The patch is designed with patterns, which consists of four concentric annular rings and some strips in radial direction. In this way, three resonances are generated, and the pattern is optimized to bring three resonances close to each other. The number of the strips is specially designed to bring three resonances close to each other. By loading the inductive vias on the outermost rings, connecting to the ground, the resonance at low frequencies can be enhanced, as a consequence of the optimized impedance matching. The field distribution is analyzed to verify the operation principle. A prototype is fabricated, and the measured results agree well with the simulated ones. The relative −10 dB bandwidth is 69% and the omnidirectional radiation pattern is stable in the operating band. The antenna achieves a rather wideband radiation while maintaining a low profile. The method of antenna miniaturization and bandwidth enhancement based on surface current engineering paves the way for antenna design in low-profile ultra-wideband applications.

DESIGN OF NEW COMPOUND RECONFIGURABLE MICROSTRIP ANTENNA FOR C AND KU BANDS APPLICATIONS

A compound reconfigurable microstrip antenna has been analyzed and designed using switching a PIN diode to switch between different modes of operating frequencies as well as radiation pattern directions. In this paper, computer simulation technology (CST) software 2020 has been used. Due to the complex calculation of the circular microstrip patch antenna, the proposed design has reduced the complexity by using a structure that is compact, easy to fabricate, cheap to produce, and uses only one PIN diode, while maintaining peak antenna performance. The suggested design is appropriate to operate in two states conditional on biasing the PIN diode. The reconfigurable patch of 31.16 mm × 27.04 mm has a compact size with 1.6 mm of thickness. It functions in both the C band at 7.1 GHz with a shift of radiation pattern direction to 4 degrees and in the Ku band at 12.5 GHz with a shift of radiation pattern direction to 28 degrees in state 2 where the PIN diode is on the state. In addition, the ON and OFF state of the switching PIN diode has been extensively investigated by changing the resistance, inductance, and capacitance values for optimal antenna performance. The proposed reconfigurable circular patch can be implemented to operate in modern communication such as Radio navigation and earth exploration, space operation, earth-to-space satellite communication, 5G applications, and Wireless-Fidelity 7.

CMA Approach for a DGS-Based Wideband Circular Patch Antenna With Low Cross Polarization

This letter presents a design approach for a defected ground structure (DGS)-based wideband circular microstrip patch antenna using the characteristic mode analysis (CMA). It emphasizes improving two design aspects: 1) cross polarization reduction and 2) bandwidth enhancement. The CMA unveils the intrinsic characteristic modes in the patch and ground plane, and then, undesired modes are suppressed using a DGS, reducing cross-polarized radiations. Another defect, strategically incorporated into the same DGS, enhances a higher-order nonradiating mode to radiate and increases bandwidth. The proposed design fabricated on an FR-4 substrate achieves a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\simeq$</tex-math></inline-formula> 16% impedance bandwidth (5.7–6.7 GHz) with dimensions <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\boldsymbol{0.8\lambda _{0}\times 0.8\lambda _{0}\times 0.03\lambda _{0}}$</tex-math></inline-formula> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\boldsymbol{\lambda}_{\boldsymbol{0}}$</tex-math></inline-formula> being the free-space wavelength at 6 GHz) and 10–15 dB average cross polarization reduction at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\pm$</tex-math></inline-formula> 60° angle of boresight. The measured results from a fabricated prototype agree well with the proposed design.

WEARABLE ANTENNA DUAL BAND WITH ELECTROMAGNETIC BAND GAP (EBG) STRUCTURE FOR HEALTH APPLICATIONS

Telemedicine can solve several issues in the healthcare system. The wearable antenna works with the Industrial, Scientific, and Medical (ISM) band for wireless body area network (WBAN) communications. Wearable antennas are lightweight, easy to make, and so on. This antenna application's bandwidth is limited by the thin substrate. This research will create a wearable planar monopole antenna with a circular patch that can operate at 2,4 and 5,8 GHz. Antenna without the UC-EBG structure and antenna with the UC-EBG structure were tested. The simulation results without UC-EBG show that the return loss is -14.629 dB and -28,639 dB, the VSWR is 1,456 and 1,077, the bandwidth is 4988 MHz, and the gain is 2,517 dBi and 4,270 dBi. The simulation results with the addition of UC-EBG show that the return loss is -13,835 dB and -17,46 dB, the VSWR is 1,511 and 1,309, the bandwidth is 1480 MHz and 2320 MHz, and the gain is 2,869 dBi and 5,208 dBi. The measurement results with UC-EBG show that the return loss is -13,134 dB and -18,421 dB, the VSWR is 1,566 and 1,273, the bandwidth is 1080 MHz and 960 MHz, and the gain is 2,198 dBi and 4,98 dBi.

Outcomes of continuous flow left ventricular assist device after surgical left ventricular restoration

ObjectivesThis study aimed to report the clinical outcomes of continuous flow left ventricular assist device implantation in end-stage chronic heart failure patients with a history of surgical left ventricular restoration.MethodsWe retrospectively identified 190 patients undergoing continuous flow left ventricular assist device implantation at our center from November 2007 to April 2020. In total, six patients underwent continuous flow left ventricular assist device implantation after various types of surgical left ventricular restoration procedures, including endoventricular circular patch plasty (n = 3), posterior restoration procedure (n = 2), and septal anterior ventricular exclusion (n = 1).ResultsContinuous flow left ventricular assist device (Jarvik 2000, n = 2; EVAHEART, n = 1; HeartMate II, n = 1; DuraHeart, n = 1; HVAD, n = 1) was successfully implanted in all patients. During a median follow-up of 48 months (interquartile range, 39–60 months; censoring heart transplantation), no death was documented, which means that overall survival after left ventricular assist device implantation was 100% at any time point. Finally, three patients received heart transplantation (waiting time: 39, 56, and 61 months, respectively) and the other three patients are still awaiting heart transplantation (waiting time: 12, 41, and 76 months, respectively).ConclusionsIn our series, continuous flow left ventricular assist device implantation after surgical left ventricular restoration was safe and feasible, even if an endoventricular patch was used, and effective for bridge to transplant strategy.

Reconfigured antenna with switchable polarization for S Band Wireless applications

This article presents a polarization-switchable Microstrip Patch Antenna (MPA) that can be flexibly reconfigured. There are little parasitic patches connected to the corners of an MPA's circular patch as a radiator. The PIN diodes have made contact with O-shaped parasitic patch elements to form the circular patch. When the truncated corners are changed, enhanced the impedance bandwidth and axial ratio bandwidth has been obtained. 3.24 GHz is a resonant frequency for an impedance match (S11 less than 10dB) and for an axial ratio (AR less than 3 dB). The antenna's ability to transition between left- and right-handed circular polarizations (LHCP and RHCP) was verified by comparison of simulated and measured results observed. Vector Network Analyzer has also been used to evaluate the anticipated MPA under high RF strength in an anechoic room. Thus, the 5G networks and their related applications have been shown to work with these observed characteristics.

Rectangular strip engraved circular patch and connected corrugated stub-based MIMO antenna for Wi-Fi/5G/WiMAX/satellite communication applications

Rectangular strip engraved circular patch and connected corrugated stub-based MIMO antenna for Wi-Fi/5G/WiMAX/satellite communication applications

A novel pattern agile microstrip antenna for modern wireless communication systems

ABSTRACT This article presents a circular microstrip patch antenna loaded with three complementary split rings (CSRRs) on the ground plane for pattern agility features. The antenna resonated at 5.3 GHz and accommodated the frequency spectrum from 5.1–5.7 GHz for different CSRR combinations. The reconfigurable pattern feature has been produced with three p-i-n diode combinations integrated with the CSRR slot on the ground patch. The CSRR combinations are utilized to change the radiation phase concerning the primary radiating circular patch. The proposed antenna radiation beam can steer from ±15°, 180°, and 0° of the broadside pattern in the elevation plane with a satisfactory gain of 3 dBi. The phase variation for various CSRR combinations concerning the primary antenna is presented. The presented antenna is fabricated on an FR4 substrate and tested in an anechoic environment; the tested results verify the pattern agility of the antenna. The demonstrated antenna is suitable for modern wireless communications like LTE and Cognitive radios. The compact size, simple biasing, and low cost are added advantages of the antenna.

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.

A compact two-state pattern reconfigurable antenna for 5G Sub-6 GHz cellular applications

This paper presents a compact pattern reconfigurable antenna for sub-6 GHz (4.8 GHz-5 GHz) applications. The proposed antenna consists of a quarter-wavelength radiator with two circular slot-loaded oval-shaped patches on both sides of the radiator. The antenna's ground plane is loaded with an inverted l-shaped structure. Two PIN diodes are used to switch the direction of radiation. Good agreement between simulated and measured results is obtained. The −10 dB impedance bandwidth of the proposed design is 370 MHz. The peak gain is 5.5dBi, and efficiency is 82 % in different diode states. The proposed antenna is then analyzed with the Nordic nRF9160 DK board to check the design reliability.

Fractal Loaded, Novel, and Compact Two- and Eight-Element High Diversity MIMO Antenna for 5G Sub-6 GHz (N77/N78 and N79) and WLAN Applications, Verified with TCM Analysis

A novel compact fractal loaded two- and eight-element multiple input multiple output (MIMO) with strong diversity is designed for 5G Sub 6 GHz and WLAN applications. The suggested antenna is designed and manufactured on inexpensive FR4 dielectric material with small size of 72 mm × 72 mm × 1.6 mm (0.792λ × 0.792λ × 0.0176λ, where λ is calculated at a lower operating frequency). The proposed layout features a partially grounded, protruding T-shaped stub on the underside of the substrate and a set of fractally loaded circular patch antenna elements on the top. Four triangular slots on the substrate and a T-shaped stub on the ground are employed to produce good isolation over the intended bands. The proposed antenna has a frequency range of (3.3–6.0) GHz, making it compatible with the 5G sub-6 GHz bands and the WLAN band thanks to its high isolation of above 15 dB and good impedance matching characteristics. Good agreement is observed between the antenna results and the theory of characteristic mode analysis approach. The designed antenna is well suited for 5G sub-6 GHz and WLAN communication applications due to its low ECC (0.005), total active reflection coefficient (TARC) (−10 dB), mean effective gain (MEG) (−3 dB), and diversity gain (DG) (−10 dB), channel capacity losses (CCL) (0.05), peak gain (&gt;2.5 dBi), radiation efficiency (&gt;95%), and stable boresight radiation patterns.