Agile Antenna Research Articles

Design of agile monopole antenna for WiFi and WiMAX applications

A monopole antenna with frequency diversity has been designed. Depending on the state of one PIN diode, this antenna has the ability to alter between two frequencies. The first one is 2.45 GHz which corresponds to the WiFi applications. The second is 3.45 GHz which corresponds to the WiMAX applications. This monopole antenna has been excited by a 50Ω microstrip line. The radiating element and a partial ground plane, that was used to achieve better gain and better bandwidth, have been printed respectively at each side of an FR4 substrate having total dimensions of 30mm × 40mm × 1.6mm. The parameters related to this antenna are analyzed using the HFSS software. For the two cases of operation of the antenna, the reflection coefficient and the gain have been simulated and showed good results. Also, for the two resonance frequencies, the VSWR is strictly lower than the value 1.2.

Wireless Multiplexing Agile Antenna-Based Control System

Multiplexing and Multiple access technologies are becoming vital components for high-performance wireless communication system. Whereas multiplexing techniques employing either multiple antennas or multiband/wideband antennas for multiplexing are commonly used, these techniques have inherent drawbacks. A feasible solution to this is to employ frequency reconfigurable or frequency agile antennas. This approach has advantages from both multiple antenna and multiband/wideband antenna designs. In this paper, a hardware implementation of a proposed biasing and control circuit/system for wireless multiplexing that utilizes a frequency reconfigurable or frequency agile antenna is reported. The device comprises a microcontroller, DAC, CMOS oscillator, power module and a USB interface for communication with a custom-built software installed on a PC. The device has functions for control, digital signal processing and de-multiplexing. The device is fed with an input multiplexed signal, and the de-multiplexed output signals are extracted and displayed on the graphical user interface of the software. Due to the re-configurability and programmability of the device, it presents a flexible, cost effective solution for a variety of real-world applications.

Magnetic behavior of Ga doped yttrium iron garnet ferrite thin films deposited by sol-gel technique

Yttrium Iron Garnet (YIG) ferrites thin films having compositional formula Y3GaxFe5-xO12, where (x = 0, 1, 2, 3, 4) are synthesized by sol gel dip coating technique. XRD, SEM and VSM characterizations are employed to explore structural, morphological and magnetic properties, respectively. XRD showed that Ga is completely doped in YIG and not formed any cluster or other phase with YIG. SEM confirmed the formation of agglomeration of YIG particles. Magnetic parameters like coercivity, remnant squareness, saturation magnetization, magnetic moment, anisotropy constant, initial permeability Y–K angles and microwave frequency were calculated of these films. The coercivity and moderate magnetization suggested that fabricated ferrite films are highly applicable in electromagnetic microwave absorption and frequency agile antenna for wireless communication.

Polarization Agile Antenna for Underwater Communication Using Integrated Power Divider and Phase Shifter

This paper presents a polarization agile antenna design that can be helpful for underwater communication, using the integrated structure of power divider and phase shifter to feed a square patch antenna. The purpose of this research is to discover new ways of communication by developing a polarization agile antenna, integrated feeding structure that can generate two equal-amplitude signals with fast phase switching between $$90^{\circ }$$ and $$270^{\circ }$$ , realizing the agility control for the dual circular polarization of the square patch antenna. Compared with the traditional polarization-agile antennas with the individual power divider and phase shifter networks, the proposed design has the advantages of good amplitude, phase and polarization imbalance performances, a simple control circuit, low insertion loss, and compact design which proves it to be best underwater communication.

New Agile Matrix Antenna for Nano-satellite Telemetry Using Bimodal Pattern Reconfiguration

This review deals with the design of a new reconfigurable beam antenna used to improve the efficiency of spatial telemetry links on Nano-Satellite. Advances in this domain show the needs to serve some applications with special electromagnetic beams and polarization patterns especially from LEO and MEO Space-Earth links. The RF front end must be capable to switch from high gain directive pattern to special pattern called Isoflux where the gain must be concentrated at high elevation angles with another challenge also the circular polarization. The content is a part of the CNES project that serves for multimode beam forming applications. This agile beam antenna is not built on the well-known array concept: AESA stands for Agile Electronically Scanned Array but using a new approach called ARMA standing for Agile Radiating Matrix Antenna. Contributions will show the small size elementary antenna of ARMA called Pixel, the polarization circuits that fit the challenges of the Nano-Satellite dimensions, the enhancement in the circular polarization requirements and theoretical and experimental comparison. Special beam forming required in the telemetry applications are achieved with better gain especially for the aim of wide beams. The use of the new approach will show the beam forming advantage of radiating the energy to high elevation angles.

Frequency Agile Microstrip Patch Antenna Using an Anisotropic Artificial Dielectric Layer (AADL): Modeling and Design

This paper presents the modeling and design of a frequency agile antenna using an anistropic artificial dielectric layer (AADL) for multi-band phased array radar applications. The proposed AADL material is placed underneath the patch radiator and is designed using periodically arranged metallic cylinders in which varying height, diameter, and the distance used between them allows the control of the effective permittivity of the patch antenna. Closed form design expressions are formulated to synthesize the dielectric properties of the AADL as a function of the cylindrical unit cell dimensions. Design trade-offs based on the proposed formulation and numerical simulations show the overall performance of the AADL on microstrip patch (MS) antennas. To validate the proposed concept, five individual AADL MS patch antennas in C-band were designed, fabricated, and tested. Simulated and measured results ( ${s}$ -parameters and radiation patterns) are in good agreement with the results obtained from the theoretical model. The proposed AADL concept has the potential to be used in the development of future reconfigurable tunable multiband antennas that use liquid metal to dynamically change the heights of the cylinders.

Elliptically polarized frequency agile antenna on ferroelectric substrate

A low-profile, compact and frequency-tunable antenna made on ferroelectric substrate is presented. It is designed as a planar dipole antenna with an IDC varactor integrated in the signal line. Antenna is fed through a coplanar waveguide matched to 50 Ω. The center frequency can be tuned from 6.895 GHz to 7.050 GHz. It exhibits elliptical polarization and omnidirectional radiation pattern.

Frequency Reconfigurable Vivaldi Antenna with Switched Resonators for Wireless Applications

In this paper, a frequency reconfigurable Vivaldi antenna with switched slot ring resonators is presented. The principle of the method to reconfigure the Vivaldi antenna is based on the perturbation of the surface currents distribution. Switched ring resonators that act as a bandpass filter are printed in specific positions on the antenna metallization. This structure has the ability to reconfigurate between wideband mode and four narrow-band modes which cover significant wireless applications. Combination of the bandpass filters and tapered slot antenna characteristics achieve an agile antenna capable to operate in UWB mode from 2 to 8 GHz and to generate multi-narrow bands at 3.5 GHz, 4GHz, 5.2 GHz, 5.5 GHz, 5.8 GHz and 6.5 GHz. The measurement and simulation results show good agreement. This antenna is an appropriate solution for wireless applications which require reconfigurable Wideband multi-narrow bands antenna.

Low-Profile Independently- and Concurrently-Tunable Quad-Band Antenna for Single Chain Sub-6GHz 5G New Radio Applications

This paper presents a quad-band frequency agile antenna, with independent and concurrent frequency tunability in each band, for a tunable, concurrent, quad-band single chain radio receiver for 5G New Radio (NR). More specifically, the antenna comprises of four planar slots etched in a ground plane and fed through a single microstrip feedline, without any impedance matching network. The structure is optimized to maximize isolation between the individual slots and their respective resonant frequencies. Furthermore, a novel high order harmonic suppression method is demonstrated, which controls the current distribution via creating a fictitious short circuit in the slot antenna–enabling the antenna to achieve a much wider tuning range. Numerical simulations are verified using experimental implementation and measurements, with good agreement observed. The four slots resonate around the 830 MHz, 1.8 GHz, 2.4 GHz and 3.4 GHz frequency bands, which are independently tuned (using a varactor diode in each slot) to achieve tuning ranges of approximately 64%, 66%, 27% and 33%, respectively. More importantly, the contiguous four bands covers a total frequency tuning from 0.6 to 3.6 GHz i.e. a tuning range of approximately 143%. Finally, far-field measurements are performed and the antenna is evaluated in over-the-air testbed (quad-band radio receiver), which measures the Error Vector Magnitude performance for the individual channels. Good performance is observed, confirming acceptable isolation performance between the four bands. The data reported in this paper is available, from ORDA-The University of Sheffield Research Data Catalogue and Repository, at https://doi.org/10.15131/shef.data.11219000.v1 .

Structural elucidation and magnetic behaviour evaluation of gallium substituted garnet ferrites

Impact of gallium (Ga) on structural, morphological and magnetic properties of yttrium iron garnet (YIG) nano-sized ferrites with nominal composition (Y3GaxFe5-xO12, where x = 0.00, 0.40, 0.80, 1.20, 1.60) has been investigated. The samples were prepared via sol-gel auto combustion route. XRD (X-ray diffraction), FESEM (field emission scanning electron microscopy) and VSM (vibrating sample magnetometer) were used to unfold the structural, morphological and magnetic properties of Ga substituted YIG ferrites. Single phase structure of all samples was confirmed through XRD. Cations distribution such as site radii, hopping bond length, shared and unshared edges of the Ga substituted YIG ferrites were also determined. Physical properties such as X-ray density (Dxrd), bulk density (Dbulk), porosity and lattice parameters were found to increase with increasing Ga concentration. FESEM images represented well crystallized and homogenous grains for YIG whereas porous structures were found for Ga substituted ferrites. The grain size of these samples was found in the nano regime (40–86 nm). Magnetic properties such as magnetic saturation, coercivity, remanence, initial permeability, Bohr magneton and anisotropy constant (K) were calculated from hysteresis loops. However, Yafet and Kittle (Y-K) angles were also calculated. Y-K angles were increased with Ga concentration in YIG nano-sized ferrites. Low coercivity and moderate magnetization suggested the use of these ferrites for electromagnetic microwave absorption and frequency agile antenna for wireless communication. Furthermore, the range of operated frequency in microwave region of these nanoferrites suggests the use of these ferrites for high frequency (S and C bands) applications.

Reconfigurable Magneto‐Electric Dipole Antennas for Base Stations in Modern Wireless Communication Systems

Magneto‐electric (ME) dipole antennas, with the function of changing the antenna characteristics, such as frequency, polarization, or radiation patterns, are reviewed in this paper. The reconfigurability is achieved by electrically altering the states of diodes or varactors to change the surface currents distributions or reflector size of the antenna. The purpose of the designs is to obtain agile antenna characteristics together with good directive radiation performances, such as low cross‐polarization level, high front‐to‐back ratio, and stable gain. By reconfiguring the antenna capability to support more than one wireless frequency standard, switchable polarizations, or cover tunable areas, the reconfigurable ME dipole antennas are able to switch functionality as the mission changes. Therefore, it can help increase the communication efficiency and reduce the construction cost. This shows very attractive features in base station antennas of modern wireless communication applications.

Highly integrated VO2-based tunable antenna for millimeter-wave applications

We report the concept of a frequency tunable antenna device operating in the millimeter wave frequency domain. The ability of the antenna to switch between two frequency states is achieved by the monolithic integration of a metal-insulator transition material (vanadium dioxide, VO2). The VO2 material is an insulator at room temperature but can be driven in a high conductivity metallic state when it is electrically activated using a continuous (DC) voltage. The antenna design is based on a slot antenna excited by a microstrip line having a length that can be conveniently varied using a VO2-based switch. Following the high-frequency VO2 material characterization, we present its monolithic integration in the device prototype along with the comparison between the measured and the simulated performances of the agile antenna. Thus, depending on the VO2 material state, the antenna device can be conveniently switched between 33 and 37 GHz operating frequency bands presenting stable radiation patterns with 5.28 dBi and 5.41 dBi maximum gains, respectively.

Continuously Tunable Polarization Agile Antenna Design Using a Novel Varactor-Only Signal Control Device

This letter presents, for the first time, the design of a novel antenna with continuous control of polarization states. Polarization agility is attained by the adoption of a dual-polarized antenna and a newly developed signal control device (using varactor diodes only). The proposed circuit also features simple control circuitry, potentially wideband, almost zero dc power consumption, and is amendable to antenna array realization. For experimental demonstration, the measured results of a 1.8-GHz antenna implemented on microstrip are shown.

Ba0.6Sr0.4TiO3 thick film derived by polymer modified MOSD route for tunable microstrip antenna applications

ABSTRACTFrequency and phase agile microstrip antenna applications require relatively thick Barium Strontium Titanate (BST) films for good tunability. In this work, Polymer (PEG-200) modified MOSD process route is developed to produce cracks free (Ba0.6, Sr0.4) TiO3 Thick film on Low loss ST-X quartz substrate. Structural and electrical characteristics of the deposited films were investigated using Atomic Force Microscope, X-Ray Diffraction, C-V and C-F characterizations. XRD characterization conformed the single BST phase with polycrystalline nature of the film. AFM analysis depicted equiaxed shaped grains with average grain size and roughness of 120 nm and 4.15 nm respectively. Dielectric tunability, dielectric constant and loss tangent of the deposited films were 36.46%, 310 and 0.0213 respectively at 1 MHz frequency using MIM capacitive structure where conductive oxide LNO was used as bottom electrode. The applicability of polymer modified BST thick films over low loss substrate as composite substrate for tunable microstrip antenna applications at microwave frequency was demonstrated by design, fabrication and testing of a compact frequency tunable microstrip antenna in coplanar configuration. The tunability exhibited at X band frequency proves the suitability of developed processed route for tunable antenna applications.

A Frequency Agile Semicircular Slot Antenna For Cognitive Radio System

A frequency agile antenna is proposed with its ground plane having a semicircular shaped slot which is capable of switching the frequency to different bands, one at a time, in the wide frequency range of 5.33 GHz to 9.90 GHz. To achieve frequency agility, switching of six RF PIN diodes which are placed along the slot length is done in various combinations. Frequency tuning ratio of about 1.85 : 1 can be achieved using this design. Results such as return losses, gain, bandwidth, and radiation patterns are presented in this paper.

An Electrical Frequency Agile Patch Antenna Based on a Poly(vinylidene fluoride-trifluoroethylene) Thin Film

ABSTRACTA novel scheme of an electrically tunable microstrip patch antenna using an electroactive polymer Poly(vinylidene fluoride-trifluoroethylene) thin film as a part of substrate is presented. The suited plus DC power supply is produced and applied to adjust the permittivity of the Poly(vinylidene fluoride-trifluoroethylene) film, which is imposed directly on the copper patch of the antenna. The patch is designed to be the same size as the ground plane to guarantee the plus static electric field inside the film uniformly. With the proposed structure, an electrical frequency agile microstrip patch antenna that performs well is achieved. The measured results demonstrate that the resonant frequency can be unceasingly tuned from 3.72 to 4.025 GHz; when the DC voltage changed from 0 to 430 V, a frequency tuning range of 7.57% is obtained.

Miniaturized and reconfigurable notch antenna based on a BST ferroelectric thin film

This work deals with the design, realization and characterization of a miniature and frequency agile antenna based on a ferroelectric Ba0,80Sr0,20TiO3 thin film. The notch antenna is loaded with a variable metal/insulator/metal (MIM) capacitor and is achieved by a monolithic method. The MIM capacitance is 3.7pF, which results in a resonant frequency of 670MHz compared to 2.25GHz for the unloaded simulated antenna; the resulting miniaturization rate is 70%. The characterization of the antenna prototype shows a frequency tunable rate of 14.5% under an electric field of 375kV/cm, with a tunability performance η= 0.04.

Feeding technique for the experimental validation of EBG matrix antenna

An experimental validation for the concept of a novel agile electromagnetic band gap matrix antenna is presented. It is used for beam forming and steering. It is fed by a cardinal sine excitation. A sectorial pattern is obtained. This pattern presents a special shape with low side lobes level. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:533–537, 2015

A Novel and Compact Multi Frequency-Agile Slot Antenna for Cognitive Radio Systems

A novel and compact frequency- agile slot antenna is presented. The antenna is switchable between 5.03-6.90GHz at twenty four different frequencies and is capable to operate multi frequency at a time. The proposed antenna has two slots etched out, one in the ground plane and another in the patch. To attain frequency agility, the effective lengths of these slots are altered by use of four p-i-n diodes which are placed within these slots at predetermined positions. Results such as return losses, gain, bandwidth and radiation patterns are presented in this paper.

Passive polarization agile antenna based on the electromagnetically induced transparency-like effect

We propose a design method for a passive polarization agile antenna based on the electromagnetically induced transparency-like (EIT-like) effect. Benefiting from strong dispersion properties governed by EIT-like effects, the proposed structure can endow electromagnetic waves transmitted through it with quite different polarization states at very close frequencies. The experimental measurement was conducted to demonstrate agile polarization controls by placing a designed EIT-like waveplate in front of a standard microwave horn antenna. Results show that the polarization state of radiated waves by the horn antenna with a waveplate can be easily transformed among linear, circular and elliptical polarizations through fine-tuning the operating frequency, which is extremely important for certain special applications, e.g. electronic countermeasures. Our scheme could also be utilized at higher operating frequencies by the simply scaling principle.