Inkjet Printed Metamaterial Loaded Antenna for WLAN/WiMAX Applications

In this paper, the design and performance analysis of an Inkjet-printed metamaterial loaded monopole antenna is presented for wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications. The proposed metamaterial structure consists of two layers, one is rectangular tuning fork-shaped antenna, and another layer is an inkjet-printed metamaterial superstate. The metamaterial layer is designed using four split-ring resonators (SRR) with an H-shaped inner structure to achieve negative-index metamaterial properties. The metamaterial structure is fabricated on low-cost photo paper substrate material using a conductive ink-based inkjet printing technique, which achieved dual negative refractive index bands of 2.25–4.25 GHz and 4.3–4.6 GHz. The antenna is designed using a rectangular tuning fork structure to operate at WLAN and WiMAX bands. The antenna is printed on 30 × 39 × 1.27 mm3 Rogers RO3010 substrate, which shows wide impedance bandwidth of 0.75 GHz (2.2 to 2.95 GHz) with 2 dB realized gain at 2.4 GHz. After integrating metamaterial structure, the impedance bandwidth becomes 1.25 GHz (2.33 to 3.58 GHz) with 2.6 dB realized gain at 2.4 GHz. The antenna bandwidth and gain have been increased using developed quad SRR based metasurface by 500 MHz and 0.6 dBi respectively. Moreover, the proposed quad SRR loaded antenna can be used for 2.4 GHz WLAN bands and 2.5 GHz WiMAX applications. The contribution of this work is to develop a cost-effective inject printed metamaterial to enhance the impedance bandwidth and realized the gain of a WLAN/WiMAX antenna.     

Frequency Reconfigurable Antenna for Portable Wireless Applications

In this paper, the design and experimental evaluation of a hexagonal-shaped coplanar waveguide (CPW)-feed frequency reconfigurable antenna is presented using flame retardant (FR)-4 substrate with size of 37 × 35 × 1.6 mm³. The antenna is made tunable to three different modes through the status of two pin diodes to operate in four distinct frequency bands, i.e., 2.45 GHz wireless fidelity (Wi-Fi) in MODE 1, 3.3 GHz (5G sub-6 GHz band) in MODE 2, 2.1 GHz (3G Long Term Evolution (LTE)-advanced) and 3.50 GHz Worldwide Interoperability for Microwave Access (WiMAX) in MODE 3. The optimization through simulation modeling shows that the proposed antenna can provide adequate gain (1.44~2.2 dB), sufficient bandwidth (200~920 MHz) and high radiation efficiency (80%~95%) in the four resonating frequency bands. Voltage standing wave ratio (VSWR) < 1.5 is achieved for all bands with properly matched characteristics of the antenna. To validate the simulation results, fabrication of the proposed optimized design is performed, and experimental analysis is found to be in a considerable amount of agreement. Due to its reasonably small size and support of multiple frequency bands operation, the proposed antenna can support portable devices for handheld 5G and Wireless LAN (WLAN) applications.     

A Compact Flexible Circularly Polarized Implantable Antenna forBiotelemetry Applications

With the help of in-body antennas, the wireless communication among the implantable medical devices (IMDs) and exterior monitoring equipment, the telemetry system has brought us many benefits. Thus, a very thin-profile circularly polarized (CP) in-body antenna, functioning in ISM band at 2.45 GHz, is proposed. A tapered coplanar waveguide (CPW) method is used to excite the antenna. The radiator contains a pentagonal shape with five horizontal slits inside to obtain a circular polarization behavior. A bendable Roger Duroid RT5880 material (ε_r = 2.2, tanδ = 0.0009) with a typical 0.25 mm-thickness is used as a substrate. The proposed antenna has a total volume of 21 × 13 × 0.25 mm³. The antenna covers up a bandwidth of 2.38 to 2.53 GHz (150 MHz) in vacuum, while in skin tissue it covers 1.56 to 2.72 GHz (1.16 GHz) and in the muscle tissue covers 2.16 to 3.17 GHz (1.01 GHz). GHz). The flexion analysis in the x and y axes was also performed in simulation as the proposed antenna works with a wider bandwidth in the skin and muscle tissue. The simulation and the curved antenna measurements turned out to be in good agreement. The impedance bandwidth of −10 dB and the axis ratio bandwidth of 3 dB (AR) are measured on the skin and imitative gel of the pig at 27.78% and 35.5%, 13.5% and 4.9%, respectively, at a frequency of 2.45 GHz. The simulations revealed that the specific absorption rate (SAR) in the skin is 0.634 and 0.914 W/kg in muscle on 1g-tissue. The recommended SAR values are below the limits set by the federal communications commission (FCC). Finally, the proposed low-profile implantable antenna has achieved very compact size, flexibility, lower SAR values, high gain, higher impedance and axis ratio bandwidths in the skin and muscle tissues of the human body. This antenna is smaller in size and a good applicant for application in medical implants.     

Dual wideband coplanar waveguide-fed notched antennas with asymmetrical grounds for multi-band wireless application

A novel single-layer planar monopole antenna is proposed for dual wideband operation. The antenna is a notched patch fed by a coplanar waveguide with two asymmetrical ground planes. The parametrical effects of the size of two such grounds and an embedded notch on the impedance matching condition have been examined theoretically. By fabricating and measuring the prototypes of the proposed antenna, two bands with 10 dB return loss bandwidths of about 490 MHz centred at 2.13 GHz band and of about 99.2% ranging from 3.32 to 6.9 GHz were obtained. A stable radiation pattern and average gains of greater than 2.6 and 4.8 dBi, respectively, over the two operating bands have also been obtained. These properties make the antenna suitable for multi-frequency wireless operation.     

Reconfigurable patch-antenna design for wideband wireless communication systems

An effective design of a reconfigurable patch antenna, with a wide operational bandwidth for wireless communication and radar systems, is presented in this paper. The reconfigurable patch possesses an E-shaped structure and its operation frequency can be changed by integrated switches. The operational frequency of the antenna can cover an octave frequency range by utilising only two switch states. In state 1, the antenna operates from 9.2 GHz to 15.0 GHz and, in state 2, from 7.5 GHz to 10.7 GHz. Relative bandwidths of 48% and 35% are obtained in the two states, respectively     

A simple dual-band microstrip-fed printed antenna for WLAN applications

A novel microstrip-fed dual-band printed antenna for wireless local area network (WLAN) is presented. The antenna comprises a rectangular and a circular radiating element, which generate two resonant modes to cover 2.4/5.2/5.8 GHz WLAN bands. The design was experimentally verified by constructing the antenna on a FR4 (ϵr = 4.4) dielectric substrate (47 mm x 26 mm x 0.76 mm) and measuring its impedance and radiation characteristics at both the bands. The measured 10 dB return loss (VSWR 2:1) bandwidth in the 2.4G Hz band is 550 MHz (2.1?2.65 GHz) and it covers the bandwidth required for 2.4 GHz WLAN. The 5.2/5.8 GHz resonant mode has a bandwidth of 950 MHz (5.15?6.1 GHz) covering 5.2/5.8 GHz WLAN bands. A rigorous experimental evaluation confirmed that the dual-band printed antenna maintained good radiation characteristics with minimum cross-polarisation levels.     

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.     

Polarisation switchable slot-ring array antenna

A reconfigurable antenna is attractive for advanced wireless communication systems in the future. A novel polarisation switchable slot-ring array antenna as a kind of reconfigurable antenna is proposed. To realise the orthogonal polarisation switchable antenna, four switching diodes are mounted on a slot-ring antenna element. The both-sided MIC technology is effectively employed in forming this slot-ring array antenna. The Ansoft HFSS is used to simulate the antenna, and the characteristics of this functional antenna are discussed. The calculated results are compared with the measured ones, and these results agree well. Consequently, a readability of the polarisation switchable antenna is successfully verified.     

Dual frequency band antenna combined with a high impedance band gap surface

A compact dual-band antenna structure for automotive and aerospace applications is discussed. A bow tie dual-band electromagnetic band gap (EBG) element geometry is presented that has a reduced cell dimension compared to the wavelength yet has sufficient bandwidth for mobile communication applications. The EBG was combined with a printed planar monopole to produce a structure 8 mm thick. The return loss and radiation patterns gave satisfactory performance at two frequency bands with bandwidths of 11% at 1700 MHz and 7% at 2600 MHz. There was suppression of the back radiation at both bands of 5 dB or better even for the small 3 times 3 element EBG used and the antenna was platform tolerant.     

New CPW-fed monopole antennas with both linear and circular polarisations

A low-profile, planar, circularly polarised monopole antenna with a shorting sleeve strip fed using a coplanar-waveguide transmission line for wireless communication in the digital communication system and the global positioning system bands is studied. By utilising the coupling effect between the monopole antenna and sleeve, two excited resonant modes, including the monopole and travelling-wave modes, cover the 1.57- and 1.8-GHz bands. Through modification with antennas of various geometrical parameters, the proposed antenna exhibits the wide bandwidth in the desired frequency bands, which has a bandwidth of 45% at 1.6%GHz for an input reflection coefficient of less than %10%dB. Meanwhile, the antenna has a 3-dB axial ratio bandwidth of 5%. Details of the design considerations for the proposed antennas are described, and the results of the antenna performances obtained are presented and discussed.     

Compact wideband antenna for wireless communications

A compact dual-band printed wire antenna for applications in wireless communications is presented. An additional shorted parasitic element to the F-shaped wire antenna is introduced to achieve a dual-band operation. As an example, a new antenna was designed and fabricated for wireless local area network applications that operate in the 2.4 and 5.2/5.8 GHz bands. The prototyped antenna offered two separate measured impedance bandwidths of 700 (2.35-3.05 GHz) and 2150 MHz (3.95-6.1 GHz), for a return loss less than -10 dB. A measured antenna gain of 1.78-1.9 dBi was observed across the lower band, whereas a measured antenna gain of 3.9-4.4 dBi was observed across the upper band. The measured radiation patterns were stable across the passband     

Design of reconfigurable antennas based on an L-shaped slot and PIN diodes for compact wireless devices

A basic antenna structure to design pattern and pattern/frequency reconfigurable antennas is proposed. The structure consists of an L-shaped slot, PIN diodes, lumped capacitors and bias networks. The PIN diodes and the lumped capacitors located at specific positions are used to create short circuits across the slot. By carefully controlling these diodes, the induced current distribution around the slot can be changed, resulting in different antenna radiation patterns. Thus, a pattern reconfigurable antenna can be achieved. The proposed structure is then extended to design frequency/pattern reconfigurable antennas by introducing varactor diodes. Two compact reconfigurable antennas based on the proposed structure are designed and implemented to prove the design concepts. The experiment results fully demonstrated the performances of the proposed designs. Owing to the compact size and ease on manufacture, the proposed structure can be a promising solution in compact wireless devices such as smart phones and notebook computers.     

Quintuple Band Antenna for Wireless Applications with Small Form Factor

A coplanar waveguide-fed quintuple band antenna with a slotted circular-shaped radiator for wireless applications with a high isolation between adjacent bands is presented in this paper. The proposed antenna resonates at multiple frequencies with corresponding center frequencies of 2.35, 4.92, 5.75, 6.52, and 8.46 GHz. The intended functionality is achieved by introducing a circular disc radiator with five slots and a U-shaped slot in the feed. The proposed antenna exhibits coverage of the maximum set of wireless applications, such as satellite communication, worldwide interoperability for microwave access, wireless local area network (WLAN), long-distance radio telecommunications, and X-band/Satcom wireless applications. The simulation and measurement results of the proposed fabricated antenna demonstrate the high isolation between adjacent bands. A stable realized gain with an advantageous radiation pattern is achieved at the operating frequency bands. The proposed simple design, compact structure, and simple feeding technique make this antenna suitable for integration in several wireless communication applications, where the portability of devices is a significant concern. The proposed antenna is anticipated to be an appropriate candidate for WLAN, long-term evolution, and fifth-generation mobile communication because of its multi-operational bands and compact size for handheld devices.     

Triple-Band Circularly Polarized Dielectric Resonator Antenna (DRA) for Wireless Applications

This paper proposes a new dielectric resonator antenna (DRA) design that can generate circularly polarized (CP) triple-band signals. A triple-band CP DRA antenna fed by a probe feed system is achieved with metal strips structure on side of DRA structure. The design start with conventional rectangular DRA with F shaped metal strips on DRA structure alongside the feed. Then, the F metal strip is enhanced by extending the length of the metal strip to obtain wider impedance bandwidth. Further improvement on the antenna performance is observed by improvised the conventional DRA structure. The method of removing part of DRA bottom resulted to higher antenna gain with triple band CP. The primary features of the proposed DRA include wide impedance matching bandwidth (BW) and broadband circular polarization (CP). The primary features of the proposed DRA include wide impedance matching bandwidth (BW) and broadband circular polarization (CP). The CP BW values recorded by the proposed antenna were ∼ 11.27% (3.3–3.65 GHz), 12.18% (4.17–4.69 GHz), and 1.74% (6.44–6.55 GHz) for impedance-matching BW values of 35.4% (3.3–4.69 GHz), 1.74% (5.36–5.44 GHz), and 1.85% (6.41–6.55 GHz) with peak gains of 6.8 dBic, 7.6 dBic, and 8.5 dBic, respectively, in the lower, central, and upper bands. The prototype of the proposed antenna geometry was fabricated and measured. A good agreement was noted between the simulated and the measured results.     

Compact multiband planar monopole antennas for smart phone applications

A compact multiband planar monopole antenna is discussed. Tuning techniques, including offset feed, etching meandered slot and cutting tuning inset, are applied to the radiator in order to maximise the operating frequency range of the antenna. Experimental results demonstrate that the proposed design covers the operating bands of seven wireless services including the DCS/PCS/W-CDMA/2.4-/5-GHz WLANs/Bluetooth and the WiMAX in United States. The design concept, step-by-step guidelines, radiation mechanism and the simulated and experimental results are carefully investigated. The finite-size ground plane effect is taken into account as well. This antenna features multiband operations, almost omnidirectional radiation patterns in one of the principal cuts, and a compact size of 22.75 times 20 mm². It is especially suitable for smart phone applications which are involving in integrating multiple wireless services into a single hand-held unit.     

Reconfigurable Compact Wideband Circularly Polarised Dielectric Resonator Antenna for Wireless Applications

In this work, a novel compact wideband reconfigurable circularly polarised (CP) dielectric resonator antenna (DRA) is presented. The L-shaped Dielectric resonator antenna is excited by an inverted question mark shaped feed. This arrangement of feed-line helps to generate two orthogonal modes inside the DR, which makes the design circularly polarised. A thin micro-strip line placed on the defected ground plane not only helps to generate a wideband response but also assist in the positioning of the two diode switches. These switches located at the left and right of the micro-strip line helps in performing two switching operations. The novel compact design offers the reconfigurability between 2.9–3.8 GHz which can be used for different important wireless applications. For the switching operation I, the achieved impedance bandwidth is 24% while axial ratio bandwidth (ARBW) is 42%. For this switching state, the design has 100% CP performance. Similarly, the switching operation II achieves 60% impedance bandwidth and 58.88% ARBW with 76.36% CP performance. The proposed design has a maximum measured gain of 3.4 dBi and 93% radiation efficiency. The proposed design is novel in terms of compactness and performance parameters. The prototype is fabricated for the performance analysis which shows that the simulated and measured results are in close agreement.     

Broadband flexible comb-shaped monopole antenna

A broadband comb-shaped monopole antenna is proposed. The antenna has dimensions of 19 mm x 12 mm. The measured results show good agreement with the numerical prediction, and broadband operation with 10 dB impedance bandwidth of 44.75% (1.7-2.68 GHz). The antenna is built on one side of a flexible-printed circuit board (PCB) dielectric substrate. Folded and rolled antenna structures, which are transformed by the proposed planar antenna structure, are presented. Each antenna has a broadband impedance bandwidth that covers the PCS, UMTS, WiBro, WLAN and SDMB bands. Also, omni-directional radiation patterns over the operating bands have been obtained. The proposed antennas are suitable for mobile communication applications requiring a small antenna.     

Compact wideband Koch fractal printed slot antenna

A compact wideband printed slot antenna, suitable for wireless local area network (WLAN) and satisfying the worldwide interoperability for microwave access (WiMAX) applications, is proposed here. The antenna is microstrip-fed and its structure is based on Koch fractal geometry where the resonance frequency of a conventional triangular slot antenna is lowered by applying Koch iterations. The antenna size inclusive of the ground plane is compact and has a wide operating bandwidth. The proposed second iteration Koch slot antenna operates from 2.33 to 6.19 GHz covering the 2.4/5.2/5.8 GHz WLAN bands and 2.5/3.5/5.5 GHz WiMAX bands. The antenna exhibits omnidirectional radiation coverage with a gain better than 2.0 dBi in the entire operating band. Design equations for the proposed antenna are developed and their validity is confirmed on different substrates and for different slot sizes.     

Compact Interlaced Dual Circularly Polarized Sequentially Rotated Dielectric-Resonator Antenna Array

In this study, a compact 2 × 2 interlaced sequentially rotated dual-polarized dielectric-resonator antenna array is proposed for 5.8 GHz applications. The array is composed of a novel unit elements that are made of rectangular dielectric resonator (RDR) coupled to an eye slot for generating the orthogonal modes, and to acquire circular polarization (CP) radiation. For the purpose of miniaturization and achieving dual polarized resonance, the array is fed by two interlaced ports and each port excites two radiating elements. The first port feeds horizontal elements to obtain left hand circular polarization (LHCP). The second port feeds vertical elements to obtain right hand circular polarization (RHCP). A quarter-wave length transformer is employed to reduce the attenuation and consequently increase the array gain performance. The 35 × 35 mm² () gains were 8.4 and 8.2 dBi for port 1 and port 2, respectively, with port isolations of −33.51 dB. The design achieves a voltage standing-wave ratio (VSWR) < −10 dB and an axial ratio (AR) ˂ − 3 dB bandwidth of 2.48% (5.766 to 5.911 GHz) for LHCP at port 1 and a VSWR < −10 dB and AR ˂ −3 dB bandwidth of 2.28% (5.788 to 5.922 GHz) for RHCP at port 2. The findings of the proposed design validate its use for ISM band applications.     

V-Shaped Monopole Antenna with Chichena Itzia Inspired Defected Ground Structure for UWB Applications

Due to rapid growth in wireless communication technology, higher bandwidth requirement for advance telecommunication systems, capable of operating on two or higher bands with higher channel capacities and minimum distortion losses is desired. In this paper, a compact Ultra-Wideband (UWB) V-shaped monopole antenna is presented. UWB response is achieved by modifying the ground plane with Chichen Itzia inspired rectangular staircase shape. The proposed V-shaped is designed by incorporating a rectangle, and an inverted isosceles triangle using FR4 substrate. The size of the antenna is 25 mm×26 mm×1.6 mm. The proposed V-shaped monopole antenna produces bandwidth response of 3 GHz Industrial, Scientific, and Medical (ISM), Worldwide Interoperability for Microwave Access (WiMAX), (IEEE 802.11/HIPERLAN band, 5G sub 6 GHz) which with an additional square cut amplified the bandwidth response up to 8 GHz ranging from 3.1 GHz to 10.6 GHz attaining UWB defined by Federal Communications Commission (FCC) with a maximum gain of 3.83 dB. The antenna is designed in Ansys HFSS. Results for key performance parameters of the antenna are presented. The measured results are in good agreement with the simulated results. Due to flat gain, uniform group delay, omni directional radiation pattern characteristics and well-matched impedance, the proposed antenna is suitable for WiMAX, ISM and heterogeneous wireless systems.