Reconfigurable Microstrip Antenna Research Articles

An RHCP and LHCP polarization reconfigurable microstrip antenna for ISM band smart city applications

Abstract In this article, a microstrip antenna having circular polarization switching capability is presented. This antenna consists of a circular-shaped radiating patch with a single co-axial probe feed line. The polarization reconfigurability is achieved by introducing four symmetrical U-shaped slots and silicon PIN diodes on the radiating patch. A prototype of the design is fabricated on an FR-4 substrate with overall dimension of 70 × 70 × 1.6 mm to verify the performances. The measured results of the antenna exhibit an impedance bandwidth (S 11 < −10 dB) of 5% in the frequency range of 2.37–2.49 GHz. The maximum gain of the antenna is found to be 2.99 dBic at 2.43 GHz. The antenna shows stable radiation performances at 2.4 GHz with 4.1% of 3-dB axial ratio bandwidth, and more than 105° of 3-dB axial ratio beamwidth for both right-hand circular polarization and left -hand circular polarization which make it suitable for ISM band Smart city applications.

Flexible force sensitive frequency reconfigurable antenna base on stretchable conductive fabric

With the development of wireless technology and flexible electronics, flexible frequency reconfigurable antennas have been directly used as sensors to detect mechanical signals. As an important frequency reconfigurable antenna, microstrip antenna has been widely studied in the field of flexible and flexible electronics in recent years. However, the stretchability of microstrip antennas usually comes at the cost of reducing the conductivity of the radiated conductor. Here, we report a flexible force sensitive frequency reconfigurable microstrip antenna, which fabricated by silver fiber conductive fabric with a double-wire braided structure. In order to increase the detection of pressure, an elastic dielectric layer with a microhemispheric array was introduced into the microstrip antenna to extend the frequency band width of the reconfigurable antenna. The relative frequency of the antenna varied from 0% to −12.9%, and the sensing sensitivity was −1.9 kPa−1. As potential applications, we demonstrate the use of a flexible frequency reconfigurable antenna base on stretchable conductive fabric as a strain sensor capable of measuring bending angle and movements of a human finger. The change in the resonance frequency with the externally applied tensile strain in this antenna design has a sensitivity of 3.448, manifesting a 4.19- and a 13.79-fold increase of sensitivity when compared to those in previous reports that used arched or both-planes serpentine rectangular microstrip antenna. This is of great significance for the application of wearable antenna in wireless mechanical sensing technology.

Intelligent Design of Reconfigurable Microstrip Antenna Based on Adaptive Immune Annealing Algorithm

The application of intelligent algorithm in reconfigurable antenna design can break the inefficiency of traditional antenna design based on engineering experience and electromagnetic simulation software and can significantly improve the intelligent level of antenna design. However, the convergence rate, global search ability, and optimization accuracy of the intelligent algorithm seriously restrict the accuracy and automation efficiency of antenna design and have become the bottleneck of reconfigurable antenna rapid intelligent design. Therefore, an adaptive immune annealing algorithm (AIAA) for rapid design of reconfigurable antenna is proposed in this article. AIAA introduces the idea of adaptive crossover and mutation into the basic immune algorithm (IA), which improves its population update strategy and improves the convergence rate of the algorithm; moreover, simulated annealing (SA) operator is added to the improved IA, which enhances the global search ability of the algorithm. The standard function test results show that compared with the basic IA, AIAA improves the convergence rate, global search ability, optimization accuracy, and robustness. Finally, based on AIAA, a design scheme of frequency and pattern reconfigurable antenna is proposed. Frequency reconfigurable antennas with resonant frequencies of 8.58 GHz ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$X$ </tex-math></inline-formula> -band) and 15.83 GHz ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Ku</i> -band) and pattern reconfigurable antennas with maximum radiation directions of +39° and −39° in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">xoz</i> plane are designed based on this design method, and experimental tests are carried out. The accuracy and effectiveness of the AIAA in the design of reconfigurable microstrip antenna are verified.

Metamaterial‐based frequency reconfigurable microstrip antenna for wideband and improved gain performance

A metamaterial-based frequency reconfigurable microstrip antenna is proposed with wideband tuning range and enhanced gain. By co-designing the main reconfigurable microstrip patch unit and the upper-layer located reconfigurable negative-permeability-metamaterial resonant loop, the gain of the resultant proposed antenna is readily improved. The wideband reconfigurability of the microstrip antenna and the metamaterial unit is realized by tuning the capacitance values of the varactor diodes through altering their bias voltages. Furthermore, the effect of different number of reconfigurable metamaterial units on the gain of the proposed antenna is extensively explored, which shows the radiation pattern is largely improved since the electromagnetic energy is more concentrated and directed. Finally, the proposed antenna is fabricated and measured. The experimental results demonstrate that the operating range of the proposed antenna is within 8.6–10.3 GHz, and the reflection coefficient is less than −10 dB, and the gain is above 6 dBi. The radiation efficiency of the antenna is above 85%. The electrical size of the antenna is 0.58λ0 × 0.58λ0. As expected, the proposed antenna has the main advantage of enhanced gain performance, while performing comparable frequency tuning range.

Remote‐controlled reconfigurable hexa‐band antenna for radio frequency energy harvesting systems

SummaryIn this paper, a compact (15.5 × 32 mm2) reconfigurable microstrip antenna with hexa‐band operation for radio frequency (RF) energy harvesting applications is presented. Three PIN diodes (D3, D2, and D1) for switching action and internet of things (IoT) controlled unit for controlling the resonating frequency of the proposed antenna are used. The antenna resonates at 2.1 and 3.4 GHz (010 state), 3.3 GHz (100 state), 3.2 GHz (101 state), 3 GHz (110 state), and 2.8 GHz (111 state). The proposed antenna exhibits −10 dB simulated and measured impedance bandwidth of 150, 400, 480, 570, 370, and 400 MHz and 120, 410, 400, 470, 320, and 356 MHz in states‐010, 100, 101, 110, and 111, respectively. A maximum peak gain of 3.3 dBi and maximum bandwidth of 570 MHz at 3.2 GHz (101 state) is observed. The proposed antenna is further tested for harvested power, and maximum harvested voltage of 3.9 V, maximum harvested power of 3.013 mW, and 55.07% power conversion efficiency at 20‐dBm power source are recorded. The simulated results have been validated with experimental results.

Concentric circular compound reconfigurable microstrip patch antenna for wireless applications

The article presents a concentric circle compound reconfigurable (frequency, polarization, and pattern) microstrip antenna for lower-S band (2.0 GHz-3.0 GHz) applications. Varying the capacitance of four varactor diodes from 4.15pF (0 V) to 0.94pF (6 V), the resonant frequency of the antenna can be tuned from 2.10 GHz to 2.90 GHz (34.52% tunable bandwidth). These diodes are incorporated to bridge the gap between the circle and ring of concentric geometry. The arc slots and C-shape wings are used for polarization and pattern reconfiguration, respectively. The arc slots are etched from the edge of circle geometry and loaded with RF PIN diodes to provide the different polarization states: linear polarization, left-hand circular polarization (LHCP), and right-hand circular polarization (RHCP). Simultaneously, the pattern reconfigurability can be attained with C-shape wings, placed around the concentric circle geometry; hence, patterns are tilt at 0° and ± 50°. The pattern reconfigurability also controlled through the RF PIN diodes. The designed antenna is experimentally verified and shows the maximum gain of 4.31 dBic and 4.04 dBi in polarization and pattern reconfigurable mode, respectively. Besides, it provides an excellent axial ratio (<3 dB) and stable radiation patterns. Therefore, the proposed compound reconfigurable antenna can be served for a future communication system and improves the signal quality without any destruction.

Analysis of frequency reconfigurable microstrip patch antenna with unidirectional radiation pattern for IRNSS band

This paper presents the numerical approach for dual-band frequency reconfigurable microstrip antenna. The proposed antenna is the combination of rectangular patch and slot, which is separated by a narrow gap. Three RF PIN diodes are brought together to fill the gap and achieve dual-band frequency reconfigurability. It resonates at 1.1753 GHz (1.16 GHz—1.19 GHz) and 2.4895 GHz (2.47 GHz—2.51 GHz) with maximum gain of 1.20 dBi and 8.515 dBi, respectively. The antenna provides stable unidirectional radiation patterns at both the resonant frequencies during frequency reconfiguration operation. The proposed analytical model offers physical insight into the working of this antenna and can also be used to predict frequency switching before full-wave analysis is performed. The prototype is fabricated and compared with simulated results and is suitable for wireless communication systems especially for Indian Regional Navigation Satellite System (IRNSS) receiver.

P-054. Maternal hemodynamics assessed by USCOM® device in patients with hypertensive disorders of pregnancy during peripartum

The article presents a concentric circle compound reconfigurable (frequency, polarization, and pattern) microstrip antenna for lower-S band (2.0 GHz-3.0 GHz) applications. Varying the capacitance of four varactor diodes from 4.15pF (0 V) to 0.94pF (6 V), the resonant frequency of the antenna can be tuned from 2.10 GHz to 2.90 GHz (34.52% tunable bandwidth). These diodes are incorporated to bridge the gap between the circle and ring of concentric geometry. The arc slots and C-shape wings are used for polarization and pattern reconfiguration, respectively. The arc slots are etched from the edge of circle geometry and loaded with RF PIN diodes to provide the different polarization states: linear polarization, left-hand circular polarization (LHCP), and right-hand circular polarization (RHCP). Simultaneously, the pattern reconfigurability can be attained with C-shape wings, placed around the concentric circle geometry; hence, patterns are tilt at 0° and ± 50°. The pattern reconfigurability also controlled through the RF PIN diodes. The designed antenna is experimentally verified and shows the maximum gain of 4.31 dBic and 4.04 dBi in polarization and pattern reconfigurable mode, respectively. Besides, it provides an excellent axial ratio (<3 dB) and stable radiation patterns. Therefore, the proposed compound reconfigurable antenna can be served for a future communication system and improves the signal quality without any destruction.

P-067. Biomarkers profiles of hypertensive disorders of pregnancy on term gestational period: revival of von Willebrand factor

The article presents a concentric circle compound reconfigurable (frequency, polarization, and pattern) microstrip antenna for lower-S band (2.0 GHz-3.0 GHz) applications. Varying the capacitance of four varactor diodes from 4.15pF (0 V) to 0.94pF (6 V), the resonant frequency of the antenna can be tuned from 2.10 GHz to 2.90 GHz (34.52% tunable bandwidth). These diodes are incorporated to bridge the gap between the circle and ring of concentric geometry. The arc slots and C-shape wings are used for polarization and pattern reconfiguration, respectively. The arc slots are etched from the edge of circle geometry and loaded with RF PIN diodes to provide the different polarization states: linear polarization, left-hand circular polarization (LHCP), and right-hand circular polarization (RHCP). Simultaneously, the pattern reconfigurability can be attained with C-shape wings, placed around the concentric circle geometry; hence, patterns are tilt at 0° and ± 50°. The pattern reconfigurability also controlled through the RF PIN diodes. The designed antenna is experimentally verified and shows the maximum gain of 4.31 dBic and 4.04 dBi in polarization and pattern reconfigurable mode, respectively. Besides, it provides an excellent axial ratio (<3 dB) and stable radiation patterns. Therefore, the proposed compound reconfigurable antenna can be served for a future communication system and improves the signal quality without any destruction.

Frequency Reconfigurable Microstrip Antenna Array Based on Reconfigurable Defected Ground Structure

Wydawnictwo SIGMA-NOT wydaje czasopisma fachowe informujące swoich czytelników o najnowszych osiągnięciach naukowych i nowoczesnych rozwiązaniach technicznych w Polsce i na świecie, popularyzuje problemy techniczne oraz poszerza wiedzę i kulturę techniczną.

НАПРАВЛЕННЫЕ И ПОЛЯРИЗАЦИОННЫЕ СВОЙСТВА МИКРОПОЛОСКОВОЙ РЕКОНФИГУРИРУЕМОЙ АНТЕННЫ, ПЕРЕСТРАИВАЕМОЙ ПО ЧАСТОТЕ И ПОЛЯРИЗАЦИИ

A reconfigurable antenna is an antenna with parameters that can be varied according to therequirements of a particular situation. Under variable parameters we can understand the operatingfrequency range, radiation pattern, polarization, as well as various combinations of these parameters.In this paper, we propose the design of a reconfigurable microstrip antenna with tunablefrequency and polarization, and investigate its radiation pattern and polarisation properties. Theantenna has compact dimensions and can be used in wireless communication systems operating inthe 2–7 GHz range. 5 pin diodes are included into the antenna design to change the resonant frequencyand polarization of the antenna by turning the diodes on and off. The simulation of theproposed antenna was performed in the FEKO program and the main parameters of the antennawere obtained. The analysis of the simulation results showed that for the lower part of the studiedfrequency range (2.05, 2.45 and 3.7 GHz), the polarization is linear. When operating in the highersub-range (5.4, 5.6 and 5.75 GHz), the antenna is circularly polarized, and the direction of thepolarisation vector rotation depends on the connection of the diodes. This ability to switch polarizationto orthogonal at the same frequency allows to perform efficient signal reception in the conditionsof multipath propagation.

Concentric Ring Structured Reconfigurable Antenna using MEMS Switches for Wireless Communication Applications

This paper proposes a reconfigurable circular microstrip antenna to serve the wireless communication applications that make use frequency bands such as ISM (Industrial Scientific and Medical), WLAN (Wireless Local Area Network), UMTS (Universal Mobile Telecommunications Service). Reconfigurability is achieved with the help of four MEMS (Micro-Electro-Mechanical Systems) switches to change the frequency and radiation properties of the antenna. By choosing either of the two states of each of the MEMS switches, the radius of the circular patch is varied and subsequently the operating resonant frequency. This gives rise to multiple configurations of the antenna to serve for different wireless applications. Defected Ground Structure is employed in this design to lower the resonant frequency and improve the bandwidth. Concentric rings are implemented along with a core circular patch in order to increase the radiating area of the patch in association with the MEMS-based switches to operate in toggle mode of ON and OFF. The concentric rings also helping in obtaining dual-frequency behavior of the antenna and the measured results are showing good agreement with the simulation results.

Wideband Frequency Agile and Polarization Reconfigurable Antenna for Wireless Applications

In this article, a polarization reconfigurable concentric circle microstrip antenna with simultaneous frequency agility has presented. The frequency agility and polarization reconfigurability have been controlled by open stub cascaded branch-line coupler (OSCBLC) feed network configuration. The −10 dB tunable impedance bandwidth of 2.0 GHz to 3.0 GHz (40%) is achieved by varying the capacitance of four varactor diodes from 4.15pF (0 V) to 0.84pF (7.5 V). These varactor diodes are fixed between the circular patch and ring. The polarization is reconfigured by directing the input RF through a single pole 4 throw (SP4 T) and routed to a single pole double throw (SPDT) switch in the feed network configuration. The right-hand circular polarization (RHCP) and left-hand circular polarization (LHCP) are realized in the antenna by exciting the feed ports with a time phase difference of ± 90°. Similarly, the vertical linear polarization (V-LP) and horizontal linear polarization (H-LP) are attained in the antenna by excited any one port through the feed network. The impedance bandwidth (1.5 GHz to 3.5 GHz) of OSCBLC feed network configuration is well-matched with the agile wide impedance bandwidth of the designed antenna. The proposed designed antenna shows good agreement between simulated and measurement results for polarization reconfigurability and frequency agility.

A frequency reconfigurable microstrip antenna based on graphene in Terahertz Regime

In this paper, a frequency reconfigurable THz antenna is presented. The antenna is a microstrip antenna including a rectangular patch and a slotted ground plane. To realize frequency reconfigurable antenna in THz band, graphene is used instead of PIN diodes. The antenna is enable to work in different modes by changing the parameters of graphene. This ability can replace ON or OFF state of the diode. By working in these different modes, the operation frequency of the proposed antenna changes from 2.8 to 4.2 THz. Suitable radiation patterns, wide impedance bandwidth more than 10%, a good impedance matching, and an average gain of 2dB are achieved throughout the most the antenna’s operation states.

A compact polarization reconfigurable stacked microstrip antenna for WiMAX application

AbstractIn this paper, a stacked microstrip patch antenna with polarization reconfigurable property has been proposed for worldwide interoperability for microwave access (WiMAX) application. The proposed antenna has two substrate layers: upper and lower layers with two radiating patches connected with the coaxial probe. Without the upper layer the lower square-shaped substrate layer having regular hexagonal radiating patch with probe fed acts as a linear polarized antenna with impedance bandwidth for (S11 ≤ −10 dB) is 370 MHz 10.56% (3.32–3.69 GHz) cover WiMAX (3.4–3.69 GHz) application band. The hexagonal radiating patch is perturbed with an optimum rectangular slot to enhance the impedance bandwidth of the antenna. The lower substrate layer having hexagonal patch with the same probe position is stacked with the upper square-shaped substrate layer with same sized square patch and the upper patch soldered with the coaxial probe. The overall stacked antenna generates a circularly polarized band when the opposite corner of the top square radiating patch of the upper layer is truncated with optimum size. In order to generate another circularly polarized band and to improve the input impedance matching of the stacked antenna, the top radiating patch is perturbed with two slots and a slit. The stacked circularly polarized antenna generates impedance bandwidth of 12.75% (3.23–3.67 GHz) for (S11 ≤ −10 dB) with two circularly polarized bands (3.34–3.37 GHz) and (3.66–3.70 GHz) as per (axial ratio ≤ 3 dB) for WiMAX application. Therefore, the proposed antenna can be used as linearly polarized or dual band circularly polarized according to requirement.

Liquid-Crystal-Embedded Aperture-Coupled Microstrip Antenna for 5G Applications

This letter presents a novel reconfigurable microstrip antenna with a frequency of 28 GHz and an embedded liquid crystal (LC). First, a novel fabrication process that employs a heat press machine is developed. This allows for the successful creation of thin substrates with thicknesses ranging between 0.13 and 0.25 mm. It is validated that the proposed stacked topology achieves a wide tunable range of resonant frequency. In addition, a simple bias configuration is achieved by connecting the bias position to the middle of the patch, where radio frequency (RF) potential is zero. The proposed antenna adopts a three-layer stacked printed circuit board (PCB) structure to render a cavity in which the LC is injected. The bottom patch of the top substrate is designed to contact the LC, and thus, it simultaneously functions as a dc bias electrode and a radiating element. In addition, unlike conventional stacked patch antennas, the additional patch on the top of the PCB structure is tuned to enhance gain. Compared with the simulated performance of a prior LC-based antenna, the tunable range of the resonant frequency of the proposed antenna is improved by more than three times at a center frequency of 28 GHz and the peak radiation efficiency is improved by up to 17%. Furthermore, the area (252 mm2) of the proposed LC-based antenna is 40% of the area of the prior LC-based antenna (625 mm2).

Optimal Design of Aperiodic Reconfigurable Antenna Array Suitable for Broadcasting Applications

An aperiodic reconfigurable microstrip antenna array is designed to serve as a DVB-T base station antenna operating in a single broadcasting channel. The antenna array is optimized at 698 MHz (center frequency of DVB-T channel 49) to concurrently achieve a particular radiation pattern shaping with high forward gain, main lobe tilting and null filling inside the service area, as well as low sidelobe level outside the service area, and low standing wave ratio at the inputs of all the array elements. To concurrently satisfy all the above requirements, both the geometry dimensions and the array feeding weights (amplitudes and phases) are optimized, thus leading to a complex multi-variable and multi-objective problem. The problem is solved by applying a recently developed particle swarm optimization (PSO) improved variant, called PSO with velocity mutation, in conjunction with the CST software package, which is employed by the PSOvm every time a full-wave analysis is required. Furthermore, all the optimization methods found in the CST environment are compared with the PSOvm. The results show that the PSOvm is capable of producing an antenna array geometry, which is closer to the predefined requirements than the geometries derived by the rest of the optimizers, in the least amount of computational time.

New modeling of reconfigurable microstrip antenna using hybrid structure of simulation driven and knowledge based artificial neural networks

Knowledge-based modeling has a critical role to embed existing knowledge to improve modeling performance. Since reconfigurable antenna can provide more operational frequencies than the classical antennas, a knowledge-based hybrid structure is used in this work to obtain efficient model and producing optimum new models for a reconfigurable microstrip antenna. The hybrid structure consists of two phases. The first phase generates initial knowledge which is used in knowledge-based modeling structure to obtain design parameters. Artificial neural network based multilayer perceptron can generate necessary knowledge for a knowledge-based model after the training process. Knowledge-based modeling improves the accuracy of the initial model to determine design parameters corresponding to the design target. Source difference, prior knowledge Input and prior knowledge input with difference can be applied to realize an efficient knowledge-based strategy. 3D-EM simulation generates the new model in terms of the design parameters of the proposed application. It has three switching states for operating, which are organized by two resistor circuits representing ON/OFF states. Switch positions and geometrical parameters can be used for satisfying design targets between 1 GHz and 6 GHz for the efficient antenna design.

Design of Reconfigurable Stacked Patch Microstrip Antenna (RSPMA) at 1.8 GHz and 2.3 GHz

This paper presents a Reconfigurable Stacked Patch Microstrip Antenna (RSPMA) uses a combination of aperture coupled technique and stacked patch technology for reducing feigned radiation patterns. This RSPMA consists of three FR-4 substrate layers with 4.7 mm thickness each and 3 mm thick of an air-filled substrate between stacked patches and the ground plane. The top patches are rectangular shaped with a T-shaped hole at the center and the bottom patches are T-shaped, both etched on top of substrate 1 and substrate 2 respectively act as a radiating element. Two H-shape designs of aperture slots of different sizes on the ground plane are positioned at the center of the ground plane with reference to the top patches and bottom patches. A copper strip is used as an ideal RF switch is implemented at the feed line network for the ON and OFF mode. Thus, by adjusting the switch mode, the resonance frequencies can be varied, thus frequency reconfigurable is achieved. The activation of the selected aperture slots will produce waves and radiates the signal to the radiating layers of the patch antenna. Hence, two different frequencies, either at 1.8 GHz or 2.3 GHz were achieved through the RSPMA with the gain of 3.691 dB and 2.291 dB, respectively. The antenna designed was simulated using CST Microwave Studio at an operating frequency of 1 GHz to 2.7 GHz. The RSPMA is said to be potentially beneficial to the wireless communication system.

Dual-Sense Circular Polarization Antenna Based on Reconfigurable Orthogonal Network

A novel circular polarization (CP) reconfigurable microstrip antenna is presented. The CP reconfigurable antenna is divided into three layers, composed of an annular radiating patch, ring slot, and reconfigurable orthogonal network (RON). The designed antenna is fed by dual vertical branches at the output port of the RON. By adjusting the bias voltage of the PIN switch loaded on the reconfigurable orthogonal network, the output phase can be changed, which means that the polarization direction of CP antenna is switchable. Simulation results show that the proposed feeding network provides constant phase difference and lower insertion loss for both states in the operating frequency band, thereby achieving good match and axial ratio characteristics either LHCP or RHCP state. Measured results show that the proposed antenna exhibits operational bandwidth of 1.2% with axial ratio below 3 dB and return loss above 10 dB in both polarized states. Good agreement between simulated and measured results is obtained.