Radiation Pattern Reconfigurable Antenna Research Articles

Radiation Pattern Reconfigurable Arch-Shaped Dual-Band Antenna for Wi-Fi and WLAN Applications

This paper describes the design and analysis of a reconfigurable radiation pattern dual-band antenna for Wi-Fi and WLAN applications. The antenna patch comprises two parts: the upper part, which consists of three symmetrical oval rings, and the lower part, which is shaped like a lotus flower. By controlling the ON and OFF states of lumped p-i-n switches to control the direction of the radiation beams, the proposed pattern reconfigurable antenna achieves three reconfigurable states. The beam's direction change is performed by two switches that are connected in the gap between the feedline and the arch. The proposed antenna operates at 2.4 and 5.5 GHz, covering the bands from 2.1882 to 2.55 GHz and from 5.31 to 5.96 GHz, respectively. Additionally, the directivity over the working bands is about 1.92 to 4 dBi while the gain lies in the range of 1.66 to 3.5 dB. Moreover, the voltage standing wave ratio (VSWR) varies from 1 to 1.20. The size of the antenna is 47×59.5 mm2 which is printed on a 1.6 mm thickness FR-4 substrate of 4.4 relative permittivity. Computer simulation technology Microwave Studio is used to design and study the recommended constructions. The proposed design achieves an acceptable value of VSWR, stable gain, and good directivity, which makes it a suitable choice for future radiation pattern reconfiguration applications. The proposed antenna is distinguished by a simple shape, compact size, respectable return loss, good radiation characteristics, and high efficiency. The obtained results from measurements are quite close to the simulations.

Intelligent Frequency, Radiation Pattern and Polarization Reconfigurable Antenna for 5G Applications

Intelligent Frequency, Radiation Pattern and Polarization Reconfigurable Antenna for 5G Applications

Low-Profile and Wider-Angle Beam Tilting Parasitic Array Resonator Antenna with Optimized Deflected Ground Plane on FR-4 Substrate

A low-profile and wide-angle radiation pattern reconfigurable antenna is designed, analyzed, and fabricated for wireless sensor network (WSN) applications, which operate at a 2.5-GHz frequency. This work aims to minimize the number of switches and optimize the parasitic size and ground plane to achieve a steering angle of more than 30° using a low cost-high loss FR-4 substrate. The radiation pattern reconfigurability is achieved by introducing four parasitic elements surrounding a driven element. In this work, the single driven element is fed by a coaxial feed, while other parasitic elements are integrated with the RF switches on the FR-4 as the substrate with dimensions of 150 × 100 mm (1.67 × 2.5 λo). The RF switches of the parasitic elements are surface mounted on the substrate. By truncating and modifying the ground plane, the beam steering can be achieved at more than 30° on the xz plane. Additionally, the proposed antenna can attain an average tilt angle of more than 10° on the yz plane. The antenna is also capable of attaining other important results, such as a fractional bandwidth of 4% at 2.5 GHz and an average gain of 2.3 dBi for all configurations. By adopting the ON/OFF condition on the embedded RF switches, the beam steering can be controlled at a certain angle, thus increasing the tilting angle of the wireless sensor networks. With such a good performance, the proposed antenna has high potential to serve as a base station in WSN applications.

Wideband Pattern-Reconfigurable Antenna With Switchable Monopole and Vivaldi Modes

A novel design for radiation pattern-reconfigurable antenna is described in this letter. The design is based on a wideband Vivaldi antenna structure. Two different radiation patterns are achieved by switching the feeding paths to obtain two antennas operation modes, monopole mode and Vivaldi mode. The reconfigurable antenna can adjust the radiation patterns by controlling the bias voltage of pin diodes. Therefore, by combining the two radiation patterns, a broad coverage of reconfigurable pattern is generated. In addition, the pattern reconfigurable antenna can operate at a wide frequency band from 2.7 to 12 GHz. Details of the simulated and experimented results for the pattern-reconfigurable antenna are shown.

Parasitic Array Based Radiation Pattern Reconfigurable Patch Antenna for WLAN Application

This article presents a radiation pattern reconfigurable patch antenna using three rectangular parasitic elements for WLAN (5.8 GHz) application. A rectangular driven patch with two parasitic elements placed parallel to both non-radiating edges and the third parasitic element is located on the radiating edge of driven element. The parasitic elements located on non-radiating edges are loaded with shorting posts. The electrical connection between the post and ground plane is controlled by an RF PIN diode switch. Based on switching state (ON/OFF) of the PIN diodes, post loaded parasitic elements, switch their function between director and reflector to produce beam reconfiguration in the proposed antenna. For different switching combinations of the PIN diodes, beam steering directions in H-plane are obtained at 0˚, +50˚, –50˚ for E-plane radiation maximum at +30˚, while fourth beam steering angle is found at ±50˚ with corresponding E-plane radiation maximum at ±40˚. Measured peak gain of the proposed antenna varies between 3.46 dBi and 3.74 dBi for different beam steering modes. With measured resonant frequency around 5.85 GHz throughout the reconfiguration process, the proposed antenna is considered as a potential candidate for WLAN application.

Low-profile bandwidth and E-plane radiation pattern reconfigurable patch antenna for sub-6 GHz 5G applications

In this work, a low-profile bandwidth and E-plane radiation pattern reconfigurable microstrip antenna is presented for the fifth generation (5G) sub-6 GHz, 3.3 to 4.2 GHz band. The proposed antenna is miniaturized using a partial ground plane technique. The bandwidth and the pattern reconfigurability are realized using a reconfigurable second element feed line and an additional λ/8 connecting stub of a 2-element circular patch array. The additional λ/8 connecting stub transforms a conventional series RLC into a parallel RLC combination leading to larger bandwidth. The working principle and the design process of each iteration have been detailed. The working principle is validated using the surface current distributions in different modes and developing and testing a prototype. The proposed antenna structure has two operating modes covering from 3.28 to 4.34 GHz band; (I) measured 19.4% fractional bandwidth, unidirectional E-plane pattern and (II) 27.4% fractional bandwidth, bidirectional E-plane pattern. The measured centre frequency of both operating modes is 3.5 GHz, and 3.79 GHz with continuous coverage of the 5G band. The measured H-plane radiation pattern of the antenna is identical in both operating modes.

2D Direction of Arrival Estimation Using Uniform Circular Arrays With Radiation Pattern Reconfigurable Antennas

This paper focuses on direction of arrival (DoA) estimation using adaptive arrays that consist of radiation pattern reconfigurable antenna (RPRA) elements for 2D direction finding (i.e., azimuth and elevation DoA estimation). In particular, uniform circular arrays (UCAs) are explored that use RPRA elements with two different elevation radiation pattern states to achieve unambiguous estimates over all possible incident angles. Theoretical cardioid-type directional patterns are investigated to determine the pattern states that minimize overall DoA estimation error, and the performance of 3-, 4-, and 5-element RPRA UCAs is compared with baseline theoretical arrays composed of isotropic elements. The results demonstrate that RPRA UCAs with optimized cardioid patterns can achieve similar accuracy to the baseline arrays, but with fewer antennas/front-ends. For example, a 4-element RPRA UCA can achieve approximately the same root mean square error (RMSE) as a 6-element uniform spherical array composed of isotropic elements. Furthermore, unambiguous estimates can be achieved over all incident angles with electrically large UCA radii using optimized RPRA elements, which can further improve accuracy and increase bandwidth. To demonstrate the feasibility of the technique, a practical RPRA was designed at 6 GHz with a pattern that approximates the optimized cardioid, and the performance meets or exceeds the theoretical pattern performance for RMSEs less than 3°.

A Frequency and Radiation Pattern Reconfigurable Antenna Using Composed Structure of Pseudo-Fibonacci and DGS for 5G IoT/ WiFi 6/CR Applications

Compound reconfigurable antennas have been studied in recent research for modern wireless communication systems due to their advantage of multifunctional capabilities. In this paper, a novel composed structure of frequency and radiation pattern reconfigurable antenna is proposed. The antenna uses four pseudo-Fibonacci curves and the E shape of Defected Ground Structures (DGS) to make the varied directivity radiation. The steering beam along can achieve based on the position of the active PIN diode in different directions. The resonant frequency can also switch from one to other bands depending on the number of active PIN diodes. The antenna gets a compact size of 30mm x 30mm x 1.6mm that can be fit on a small form factor while still being able to scan along with 8 radiation directions of 0°, 90°, 180°, 270°, or 45°, 135°, 225°, 315° and 4 frequencies at 3.5GHz and 5GHz bands. The antenna directivity reaches 2.283dBi and 4.185dBi at 3.5GHz and 5GHz bands, respectively. The simulation, measurement, and experiment results agree well to ensure the proposed reconfigurable antenna can apply for terminals in 5G IoT, 5GHz WLAN, or cognitive radio systems.

Reconfigurable Pattern Patch Antenna for Mid-Band 5G: A Review

New requirements in communication technologies make it imperative to rehash conventional features such as reconfigurable antennas to adapt with the future adaptability advancements. This paper presents a comprehensive review of reconfigurable antennas, specifically in terms of radiation patterns for adaptation in the upcoming Fifth Generation (5G) New Radio frequency bands. They represent the key of antenna technology for materializing a high rate transmission, increased spectral and energy efficiency, reduced interference, and improved the beam steering and beam shaping, thereby land a great promise for planar antennas to boost the mid-band 5G. This review begins with an overview of the underlying principals in reconfiguring radiation patterns, followed by the presentations of the implemented innovative antenna topologies to suit particular advanced features. The various adaptation techniques of radiation pattern reconfigurable planar antennas and the understanding of its antenna design approaches has been investigated for its radiation pattern enhancement. A variety of design configurations have also been critically studied for their compatibilities to be operated in the mid-band communication systems. The review provides new insights on pattern reconfigurable antenna where such antennas are categorized as beam steering antenna and beam shaping antennas where the operation modes and purposes are clearly investigated. The review also revealed that for mid-band 5G communication, the commonly used electronic switching such as PIN diodes have sufficient isolation loss to provide the required beam performance.

Radiation Pattern Reconfigurable Antenna for IoT Devices

Based on the characteristic mode theory, a versatile radiation pattern reconfigurable antenna is proposed. The analysis starts from two parallel metallic plates with the same and different dimensions. By means of two PIN diodes, the size of one of the parallel metallic plates can be modified and consequently the behavior of the radiation pattern can be switched between bidirectional and unidirectional radiation patterns. Moreover, a SPDT switch is used to adjust the frequency and match the input impedance. The reconfigurable antenna prototype has been assembled and tested, and a good agreement between simulated and measured results is obtained at 2.5 GHz band which fits the IoT applications.

Radiation Pattern Reconfigurable Antenna for 5G Applications

This paper proposes a novel radiation pattern reconfigurable antenna for 5G (Fifth Generation) applications. A rectangular patch is enclosed by a hollow rectangular radiating structure. The patch is connected to the rectangular structure by two switches SW1 and SW2, which will, in turn, provide three different radiation patterns, Modes, depending on the ON and OFF states of the switches. When SW1 is OFF and SW2 is ON, Mode 1, pattern radiates in a direction with an angle of 38o. While SW1 is ON and SW2 is OFF, Mode 2, the pattern radiates in the radiating plane, exactly opposite to Mode 1, with an angle of -38o. In Mode 3, the pattern is directed simultaneously towards the angles of ±41o; for this case, both switches, SW1 and SW2, are turned OFF. The proposed design resonates in the constant 38GHz frequency range which is useful for 5G broadband cellular communication networks. And this design can also be used for 60 GHz resonant frequency with certain adjustments. Additionally, the return loss is -31.5 to -42.5, while directivity is from 5.69-6.76dB, and gain lies in the range of 5.4- to 6.4dBi. Moreover, Voltage Standing Wave Ratio, VSWR, varies from 1.01 to 1.05. The size of the antenna is 3.34x6.73mm2 which is mounted on a 0.381 mm thick, Roger RT5880 having a relative permittivity of 2.2. Central Standard Time, (CST) microwave studio software is used for simulating the design. The miniscule size, a smaller value of the return loss, an ideal value of VSWR with a reasonable value of directivity and gain make the proposed design best for future 5G mobile communications.

A Radiation Pattern Reconfigurable Fabry–Pérot Antenna Based on Liquid Metal

A new beam controllable Fabry–Perot (FP) antenna utilizing a liquid-metal partially reflective surface (PRS) is investigated. The proposed PRS can be divided into three different liquid-metal-filled areas. By injecting the liquid metal into specific zones, the antenna beam direction and 3 dB beamwidth can be controlled separately, providing an easy control method for the radiation pattern reconfigurable FP antenna. The experimental results demonstrate that the proposed antenna works at 5.1 GHz. Five beam directions in the elevation plane ( $\varphi = 90^{\circ }$ ) and four antenna horizontal beam widths can be obtained. The FP antenna is simple in design and is easily fabricated as well. It will be a good candidate antenna for future wireless communication systems.

Dual Frequency Electronically Controlled Radiation Beam Reconfigurable slotted Antenna for Detection of a Stationary or Nonstationary Target

A dual-frequency and radiation pattern reconfigurable microstrip patch antenna for detecting a stationary as well as a non-stationary target is described. Six angular patches, that collectively form a circular shape, are used. All the six patches radiate one by one after a fixed interval of time and their feed controlling is done by six PIN diodes. The switching of PIN diodes is controlled by an embedded biasing network. This antenna provides radiation beam scanning characteristics. It gives the main lobe scanning at every 60o clockwise (or anticlockwise) continuously by applying a signal to patches one by one. The purpose of introducing the slot is to get the radiation pattern in the desired direction since by changing the length, width, and position of the slot, the direction of the radiation pattern can be controlled. The slotted antenna operates in a C band with two frequencies 4.21 GHz and 4.82 GHz and provides a radiation pattern, 90o apart from each other. The scanning rate of 0.6 deg/ms is obtained; however, the scanning rate can be changed with the help of ATMEGA 2560 microcontroller. This compact Microstrip patch antenna can be widely used for short-range applications i.e. ground surveillance radar, missile control, mobile battlefield surveillance for military and many other applications in a modern wireless communication system. The designed antenna along with the switching application will be able to track the stationary as well as a non-stationary target.

Radiation Pattern Reconfigurable FM Antenna

In this work, a radiation pattern reconfigurable antenna design using compact printed spiral monopoles that operates at 102 MHz is reported. The proposed antenna changes its radiation behaviour that responds towards a desired direction with the use of RF switches. The antenna is printed on a 76.6mm × 50mm PCB layer providing more than 20MHz bandwidth at -10 dB threshold and is easily fabricated with low manufacturing cost. The antenna was also simulated on 500mm × 500mm ground plane that represents the roof top of a vehicle.

Wideband and Reconfigurable Vector Antenna Using Radiation Pattern Diversity for 3-D Direction-of-Arrival Estimation

The direction finding performances of a novel passive, wideband, and radiation pattern (RP) reconfigurable vector antenna (VA) are reported. Accurate estimation of the direction of arrival (DoA) of incoming electromagnetic (EM) fields across the 3-D half-space is obtained over a 1.69:1 impedance bandwidth from the RP reconfigurability of a four-port VA. This antenna consists of only two orthogonal and colocated semicircular arrays of Vivaldi antennas. Due to its reconfigurability, more RPs can be used in addition to those commonly employed in standard VAs to estimate the DoA of incoming EM fields. A new method based on the Cramer–Rao lower bound is proposed in order to select the RP diversity that improves the estimation accuracy across the overall bandwidth. The measured and simulated results are found in good agreement. This paper brings a further step toward developing new concepts of reconfigurable VAs.

A brief review of frequency, radiation pattern, polarization, and compound reconfigurable antennas for 5G applications

All antennas in which frequency and radiation patterns can be modified in a reversible and controlled manner are known as reconfigurable antennas. They are different from other antennas, as their mechanism of reconfiguration is located within the antenna and not controlled by an external beam. For reconfigurable antennas, the potential is not to increase the performance of the antenna in a significantly changed state or to meet the needs of dynamics and efficacy. This study will discuss various aspects related to antennas that are frequency-reconfigurable, their applications and execution frequencies, change in polarization, and changes in far-field patterns or operating frequencies to better deal with changing system parameters. For the reconfigurable antennas in this paper, some past and recent applications will be reviewed, along with examples of their implementation. The arrays and moving mechanical parts are explained, along with recently introduced semiconductor factors, and the tunable material technologies that should be applicable for reconfigurable antennas.

A Fuzzy-Based Angle-of-Arrival Estimation System (AES) Using Radiation Pattern Reconfigurable (RPR) Antenna and Modified Gaussian Membership Function

Angle-of-arrival (AOA) estimation is an important factor in various wireless sensing applications, especially localization systems. This paper proposes a new type of AOA estimation sensor node, known as AOA-estimation system (AES) where the received signal strength indication (RSSI) from multiple radiation pattern reconfigurable (RPR) antennas are used to calculate the AOA. In the proposed framework, three sets of RPR antennas have been used to provide a coverage of 15 regions of radiation patterns at different angles. The salient feature of this RPR-based AOA estimation is the use of Fuzzy Inferences System (FIS) to further enhance the number of estimation points. The introduction of a modified FIS membership function (MF) based on Gaussian function resulted in an improved 85% FIS aggregation percentage between the fuzzy input and output. This later resulted in a low AOA error (of less than 5%) and root-mean-square error (of less than 8°).

3D Radiation Pattern Reconfigurable Phased Array for Transmission Angle Sensing in 5G Mobile Communication.

This paper proposes a 3D radiation pattern reconfigurable antenna (RPRA) and a reconfigurable phased array (RPA) for 5G mobile communication. The antenna and array are working at 28 GHz, which is selected as a 5G communication band in many countries. The proposed phased array will be applied as sensors to find out the optimal transmitting–receiving angle in a randomly changed cellular wireless scenarios. The RPRA and RPA are fed by Substrate Integrated Waveguide (SIW) and have three switchable radiation modes: Broadside 1, Broadside 2 and Endfire. The three modes correspond to three different radiation patterns and each of them covers a different area in the Azimuth plane. An eight-element phased array constructed by the proposed RPRA, which is able to switch beam in Azimuth plane and scan in the Elevation plane, is also presented in this paper. The proposed RPA is able to provide much higher spatial coverage than the conventional phased arrays and without additional feeding and phase shifting networks. The beam switching is realized by the PIN diodes. The proposed antenna and array have planer structures and require small clearance on the ground plane which makes them compatible with mobile phones. The simulations show good performance for both RPRA and RPA.

Radiation Pattern Reconfigurable Waveguide Slot Array Antenna Using Liquid Crystal

In this paper, we proposed a radiation pattern reconfigurable waveguide slot array antenna using liquid crystal (LC). Together with the waveguide slot, the designed complementary electric-field-coupled resonator functions like a switch controlled by the dielectric constant of the LC, which can control the antenna element to radiate or not. Thus, the array factor and radiation pattern can be manipulated. The proposed antenna was simulated, fabricated, and measured. Its radiation direction can be reconfigured to 46° or 0° at about 15 GHz.

Parasitic Layer-Based Radiation Pattern Reconfigurable Antenna for 5G Communications

The design, prototyping, and characterization of a radiation pattern reconfigurable antenna (RA) targeting 5G communications are presented. The RA is based on a reconfigurable parasitic layer technique in which a driven dipole antenna is located along the central axis of a 3-D parasitic layer structure enclosing it. The reconfigurable parasitic structure is similar to a hexagonal prism, where the top/bottom bases are formed by a hexagonal domed structure. The surfaces of the parasitic structure house electrically small metallic pixels with various geometries. The adjacent pixels are connected by PIN diode switches to change the geometry of the parasitic surface, thus providing reconfigurability in the radiation pattern. This RA is designed to operate over a 4.8–5.2 GHz frequency band, producing various radiation patterns with a beam-steering capability in both the azimuth ( $0 {^{\circ }} ) and elevation planes ( $-18 {^{\circ }} ). Small-cell access points equipped with RAs are used to investigate the system level performances for 5G heterogeneous networks. The results show that using distributed mode optimization, RA equipped small-cell systems could provide up to 29% capacity gains and 13% coverage improvements as compared to legacy omnidirectional antenna equipped systems.