WiMAX Frequency Bands Research Articles

Dual-Wideband Rectenna for RF Energy Harvesting from 5G and WIMAX

ABSTRACT A dual wideband rectenna has been built to effectively capture radio frequency (RF) energy from 3.3 GHz to 3.7 GHz and 4 GHz to 6.3 GHz. An antenna with a rhombus form is created, which includes a rhombus slot and two rectangular strip ground planes. The planned antenna has been planned specifically to receive signals between the 3.5 GHz and 5.5 GHz frequency ranges. The highest conversion efficiency (CE) attained at 3.5 GHz and 5.5 GHz, without an impedance matching network (IMN), are 32.5% and 33%, respectively. These values are relatively low. To improve conversion efficiency, a two-line pi-impedance matching network is used, which includes DC combining. The rectenna is being evaluated for the specified frequency ranges. The highest simulated CE attained at 3.5 GHz was 81.5%, but the measured CE was 80% when the IPL was 3 dBm. The highest simulated CE at 5.5 GHz was 66.3%, but the measured CE was 65% when the IPL was 8 dBm. The proposed work is on the extraction of RF energy from the widely used 5 G and WiMax frequency bands.

Multi-frequency composite wearable antenna for wireless communications

This paper proposes a multi-band composite wearable antenna for wireless communication, which uses a monopole structure as the radiating body and achieves multi-band characteristics through slit-loading and multi-branching methods. A polymer composite substrate with high dielectric constant and low dielectric loss was prepared using in situ polymerization, and the optimal dielectric constant and loss angle tangent were obtained by controlling the coating ratio of melamine formaldehyde resin to carbon nanotubes (MWCNTs) and the filler doping rate to achieve miniaturization of the antenna. Comparative experimental results show that the obtained composites have high flexibility and good dielectric properties. The antenna operates in the frequency bands of 2.21–2.52 GHz, 3.07–3.87 GHz, and 4.36–6.03 GHz, which cover the frequency bands of WLAN and WiMAX and 5G applications. The antenna was fabricated and tested, and its performance roughly matched the simulation results. Meanwhile, the antenna has passed the SAR safety test and maintained a stable performance under different curvatures, so it has potential applications in the wireless communication system.

Compact antenna for higher order harmonic reduction using efficient defected ground structure

To suppress higher order harmonic using Inverted ‘U’ shapes defected ground structure (DGS) with two symmetric inverted ‘L’ shape stubs is presented here. At first, a study was made on the resonant frequencies of traditional line feed microstrip antenna. An Inset feed with inverted slots is introduced to eliminate all the higher-order modes up to the third harmonics in the WiMAX Band. To get wide-area stopband characteristics, dimensions and position of DGS and stubs are optimized. The proposed DGS area along with the radiated patch is more compact and stable rather than in a few reported articles. This microstrip antenna is designed and perfectly matches the WiMAX frequency band (3.3–3.7 GHz) application while suppressing other frequencies. The proposed inverted ‘U’ shapes DGS are designed with an equivalent circuit. Finally, the proposed Stub with DGS Antenna (SDA) is fabricated and measured. The proposed structure is verified with measurements and it has satisfactory gain, radiation pattern and reflection coefficient at 3.5 GHz.

Compact Ultra-­Wideband Planar Inverted F Antenna on Laminated Paper­-Based Substrate with Reduced Specific Absorption Rate

This paper presents a laminated paper-based Planar Inverted F Antenna (PIFA) for wireless body area network (WBAN) applications. The major challenges like providing adequate thickness, uniformity of surface, and water wet ability associated with paper substrate have been transcended in this antenna design by laminating the substrate with a transparent sheet. The simulated and measured reflection coefficients of the fabricated antenna in free space and on human arm are remarkably good, validating the prototype’s utility. It can operate effectively in GSM, WMTS, GPS, DCS, ISM, WiMAX, HIPERLAN, WLAN, and UWB frequency bands with S11 less than -10 dB and the gain ranging from 0.94 to 9.53 dB (free space) and 1.03 to 6.07 dB (on-body). The electrical size of the proposed antenna is 0.16 λg x 0.12 λg at 0.7 GHz with a group delay below 2.3 ns over the desired frequency bands. The performance characteristics are also investigated on-body and it encompasses most of the desired frequency bands for the body area network. This paper also analyses the specific absorption rate (SAR) of the designed antenna by placing it on a tissue-layered human arm model, which is 0.64 Watt/kg, complying with the SAR safety guidelines.

A Multi-Frequency Omnidirectional Antenna Based on a Ring-Shaped Structure.

A multi-frequency microstrip antenna loaded with a ring-like structure has been proposed. The radiating patch on the antenna surface consists of three split-ring resonator structures, and the ground plate consists of a bottom metal strip and three ring-shaped metals with regular cuts to form a defective ground structure. The proposed antenna works in six different frequency bands covering 1.10, 1.33, 1.63, 1.97, 2.08, and 2.69 GHz and works entirely when connected to 5G NR (FR1, 0.45-3 GHz), 4GLTE (1.6265-1.6605 GHz), Personal Communication System (1.85-1.99 GHz), Universal Mobile Telecommunications System (1.92-2.176 GHz), WiMAX (2.5-2.69 GHz), and other communications frequency bands. Moreover, such antennas also have stable omnidirectional radiation properties across different operating frequency bands. This antenna meets the needs of portable multi-frequency mobile devices and provides a theoretical approach for the development of multi-frequency antennas.

A multiband quasi‐Yagi antenna using stepped driver and slotted ground for 2.4/3.5/5.2 GHz bands applications

AbstractA multiband quasi‐Yagi antenna using a stepped driver and slotted ground for the applications of 2.4/3.5/5.2 GHz bands is presented. The ground plane modifications match impedance and help form the resonances, while the stepped driver parameters allow independent control of resonance frequencies. The antenna shows multiband characteristics and has achieved dB in three different frequency bands of 2.15–2.65, 3.4–4, and 5–5.3 GHz. Furthermore, the antenna shows a stable gain of around 3.9–4.9 dBi and retains its general radiation characteristics for all frequency bands. The simulation and measurement results agree well with each other. The proposed antenna is suitable for applications requiring general quasi‐Yagi antenna characteristics for wireless communications applications for WLAN, WiMAX, ISM, and Bluetooth frequency bands.

Dual-Band Highly Isolated Eight-Element MIMO Antenna for 5G Mobile Phone

Based on the characteristic mode analysis (CMA) theory, a compact dual-band dual antenna pair with high element isolation function for 5G mobile terminal is proposed and designed in this paper. The antenna pair is composed of a pair of symmetrical stacked F-shaped radiators printed on the outside of the side frame, perpendicular to the main board. Based on the proposed decoupled antenna pairs, four pairs of antenna pairs are placed at both ends of two long side plates, and an 8-element MIMO antenna is proposed. High isolation in the operating frequency bands are achieved by using grounding branches and defective ground structure (DGS). All radiation elements are etched on a low-cost FR4 substrate with a total size of 150 × 75 × 6.8 mm3. The prototype of the antenna array is fabricated and measured. The working range of the antenna pair can cover 3.4GHz-3.6GHz,4.8GHz-5GHz 5G frequency bands and 5GHz-6GHz WLAN / WiFi / WiMax frequency bands. Besides, the isolation between any adjacent array elements are also > 15dB and > 16dB respectively, the total efficiency are 52%–75% and 58%–88% respectively, and the measured envelope correlation coefficients (ECC) are <0.16. Furthermore, user’s head effects are investigated and desirable results are obtained. The above results show that this proposed antenna array is a good candidate for MIMO applications in 5G smartphones.

Design and performance analysis of a compact, wideband dual polarized antenna for WLAN & WiMAX applications

Abstract Dual polarization is achieved by putting a rectangular or circular patch in between two orthogonal gaps. At the beginning a single-polarized patch is considered. Then by using anequivalent circuit, the impedance matching property of the gap is being configured. After optimization of the length of the patch and width of the gap, a dual polarized antenna is being considered. Here in this article we projected a new technique to design dual polarized microstrip antenna for WLAN, WiMAX, wireless applications using circular patch. By combining all resonant modes we have finally achieved a wide operating bandwidth. Experimental result of the projected antenna shows the operating bandwidth of 21.56% (5.24–6.37 GHz) for (differential mode S-parameter) S dd11 ≤ −10 dB with a high port isolation of 40 dB and a relative gain of 13.5 dBi is achieved. From the result analysis this antenna finds its applications for various WLAN and Wi-MAX frequency band.

Design and Performance Analysis of a Compact Planar MIMO Antenna for IoT Applications.

This article presents a quad-band multiple-input-multiple-output (MIMO) antenna for the Internet of Things (IoT) applications. The proposed antenna consists of four quarter-wavelength asymmetrical meandered radiators, microstrip feed lines, and modified ground planes. The antenna elements are arranged in a chiral pattern to improve isolation between them, with two radiators and two ground planes placed on the front side of the substrate and the other two on the back side. The MIMO antenna has an operating bandwidth (S11 ≤ −10 dB) of 1.76–1.84 GHz, 2.37–2.56 GHz, 3.23–3.68 GHz, and 5.34–5.84 GHz, covering GSM, WLAN, WiMAX, and 5G frequency bands. The isolation between the radiating elements is greater than 18 dB in the operating bands. The peak gain of the antenna is 3.6 dBi, and the envelope correlation coefficient (ECC) is less than 0.04. Furthermore, the proposed antenna is validated for IoT-based smart home (SH) applications. The prototype MIMO antenna is integrated with a commercially available ZigBee device, and the measured values are found to be consistent with the expected results. The proposed MIMO antenna could be a good candidate for IoT systems/modules due to its low profile, compact size, lightweight, and easy integration with wireless communication devices.

Design of a linear to circular polarization converter integrated into a concrete construction for radome applications

AbstractIn this paper, we present a linear to circular polarization converter integrated in a concrete structure to eliminate signal transmission problem originated from the concrete buildings in microwave regime. Two polarization converter samples and a control specimen made by traditional concrete are designed and their signal transmission responses are compared experimentally. Axial ratio values which can be calculated by the ratio between the co-polar transmission and cross-polar transmission results of the proposed samples are below 3 dB and highly sufficient for linear to circular polarization conversion activity. The operating frequency for the proposed sample 1 is between 6 and 6.5 GHz with 500 MHz of bandwidth. The proposed sample 2 exhibits dual-band operation covering frequency bands, 4.58–5.13 and 6.0–6.4 GHz with bandwidths of 550 and 400 MHz, respectively. Operating frequencies of the samples are in the WIMAX frequency bands. In addition, the liner to circular polarization converter design integrated to concrete has a huge potential to improve reflection and directivity parameters of many antennas if it is considered as a radome.

A magnetic‐free in‐band full‐duplex RF front‐end with antenna balancing structure

In this article, a design of magnetic-free in-band full-duplex (IBFD) RF front-end with antenna balancing structure is presented. The proposed magnetic-free IBFD RF front-end consists of 3 dB hybrid couplers, a Wilkinson power divider, two transmitter (Tx) antennas, and two receiver (Rx) antennas. The proposed IBFD RF front-end can be implemented and integrated at high frequencies because all the components used in the circuit are non-magnetic devices. Proposed IBFD RF front-end eliminated the 3-dB Tx insertion-loss of the Balun and transformer in conventional IBFD RF front-ends using antenna balancing structure. Moreover, there is no noise figure degradation at Rx because it realized only a passive circuit. The mathematical analysis of the cancellation characteristics between two different signals with magnitude and phase difference variations according to the normalized frequencies is presented. Accordingly, the broadband out-of-phase balancing power splitter and the antenna balancing structure are adopted to achieve broadband SIC. In order to verify the electrical performances of the proposed magnetic-free IBFD RF front-end, it was implemented at the 2.5 GHz WiMax frequency band. When the fabricated IBFD RF front-end was operated with antenna balancing structure, the measurement results show that the 60 dB SIC bandwidth and maximum SIC were 113 MHz (2.446 - 2.559 GHz) and 75.6 dB, respectively.

A Dual Band AMC Backed Antenna for WLAN, WiMAX and 5G Wireless Applications

This paper presents a multiband low profile antenna aimed for its application in existing WLAN, WiMAX and sub-6 GHz fifth generation (5G) frequency bands. The design incorporates a simple planar monopole antenna with slots etched on it to be able to operate in two frequency bands with (S11< -10 dB) ranging from 2.38 - 2.7 GHz and 3.28 - 5.8 GHz with percentage impedance bandwidths of 16 and 56. The peak gains of the antenna within the bands were observed to be 2.1 and 4.3 dBi respectively. In order to further enhance the Gain and improve the radiation characteristics of the antenna, a dual band artificial magnetic conductor (AMC) surface is designed and employed as a reflector at the ground side of the main radiator. The antenna and AMC 4x4 array prototypes are fabricated and its performance is measured. It is observed that there is an enhancement in the gain of 5 dB in the first band and 2.8 dB in the second band of operation.

A compact circularly polarized cubic DRA with unit-step feed for Bluetooth/ISM/Wi-Fi/Wi-MAX applications

In this manuscript, a compact single fed broadband circularly polarized (CP) cubic dielectric resonator antenna (DRA) with partial ground plane is designed, analyzed and reported. The cubic DRA (Al2O3) is excited by a novel unit-step printed microstrip feed on substrate, which generates orthogonal modes i.e. TEδ11x and TE1δ1y to achieve broadband CP characteristic. Both orthogonal modes TEδ11x and TE1δ1y at 2.9 GHz are verified by the electric and magnetic field distribution inside the cubic DRA. For better understanding the CP radiation, mathematical modelling is persuaded and related with the proposed DRA. To evaluate pulse transmission characteristics, time-domain analysis is investigated which shows obtained group delay is less than 2 ns within operating frequency band. The proposed prototype antenna is fabricated and experimentally verified. Measured results show that the cubic DRA with unit-step feed provides impedance bandwidth (S11 < −10 dB) of 60.16% [2.15–4 GHz] and axial ratio (AR) bandwidth (AR < 3 dB) of 54.6% [2.18–3.75 GHz] respectively. Other antenna parameters like peak realized gain and radiation efficiency are 4 dBi and >80% within operating frequency band. A good agreement is achieved in between simulated and measured outcomes. It also suggests that proposed antenna can be a suitable candidate for diverse wireless applications operating at Bluetooth/ISM/Wi-Fi/Wi-MAX frequency bands.

Reconfigurable Quad-Band Antenna for Wireless Communication

This letter presents a thorough procedural investigation of a highly compact reconfigurable quad-band monopole antenna providing multiband operation at 1.85 GHz (GSM 1900 MHz), 2.42 GHz Bluetooth/IMTE, 3.4 GHz (Wi-MAX) and 5.3 GHz wireless LAN (WLAN) for personal wireless applications (PWA). The investigated antenna structure consists of a ‘5′- shaped stub that facilitates operation for GSM applications and a semicircular arc for Bluetooth/IMT-E applications, while an inverted L-shaped stub facilitates dual-band operation for Wi-MAX and wireless LAN applications. The presented antenna is fed using an asymmetrical coplanar strip-line (ACS) feed. The triple-band frequency reconfiguration operation, over the Bluetooth, Wi-MAX, and WLAN frequency bands, is achieved by embedding two PIN diode RF switches. The investigated antenna is developed on a highly economical FR-4 glass epoxy substrate that is 1 mm thick with a compact size of 24 × 10 mm2. The presented antenna has measured impedance bandwidths of 1.7–1.91 GHz (BW = 11.63%), 2.35–2.55 GHz (BW = 10.31%), 3.3–3.7 GHz (BW = 11.428%) and 5.10–5.6 GHz (BW = 9.345%) providing frequency reconfigurable quad-band operation at the aforementioned frequency bands. The antenna offers simulated gains of 1.8, 3.45, 4.91 and 0.86 dBi; measured gains of 2.3, 2.7, 2.82 and 2.6 dBi and radiation efficiencies of 83%, 61%, 82% and 86% at 1.85 GHz, 2.42 GHz, 3.4 GHz and 5.3 GHz, respectively. The investigated antenna exhibits nearly symmetrical radiation patterns and stable acceptable gains across all application bands, thus making the antenna suitable for wireless communication.

A miniaturized wideband and multi-band on-demand reconfigurable antenna for compact and portable devices

A miniaturized frequency reconfigurable CPW-fed antenna operating in the UWB, ISM, WiMAX, WLAN, Wi-Fi, C-band and 5G sub-6 GHz frequency bands is proposed here. The wideband CPW-fed triangular patch is made tunable to three triple-frequency bands on demand by connecting it to different serpentine stubs by using PIN diodes. The combination of triangular patch and serpentines introduced overall 8 number of operating bands (2.45, 3.05, 3.3, 4.1, 4.6, 5, 6 and 6.2 GHz) instead of a wideband (3.78–7.08 GHz) generated by triangular patch. The simulation results of the antenna are in good agreement with the measured results. The phenomena of miniaturization and multiband operation along with a wideband are compared with state-of-the-art antennas presented in the literature to highlight the significance and novelty of the proposed antenna. The proposed antenna has its applications in compact and portable devices operating at multiple frequency bands like, cellular phones, Tablets, Wi-Fi devices etc.

The Smallest Form Factor Monopole Antenna with Meandered Radiator for WLAN and WiMAX Applications

ABSTRACT The demand for designing antennas having multiband operations along with very compact dimensions is increased recently. Compact and low-profile antennas are required which can be used with multiple communication standards in a portable device. This work presents the smallest form factor multiband antenna, which is very compact, low profile, and covers triple-band for wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications, simultaneously. The proposed smallest form factor antenna comprises two asymmetric meandered-shaped elements and a partial ground plane for triple-band operations. Designed on a standard and low-cost FR4 substrate, the physical size of the antenna is 20 × 20 mm2 equivalent to 0.15 λ ° × 0.15 λ ° that has been found to be resonating in three bands, i.e. 2.4–2.53, 3.3–4.15, and 5.13–6.2 GHz. An experimental prototype shows that the antenna is satisfying the WLAN (2.40/5.20/5.80 GHz) bands and WiMAX (3.50/5.50 GHz) frequency bands and exhibits acceptable gain in the passbands, good radiation performance and advantageous radiation patterns in the resonant frequencies. The proposed smallest form factor antenna will establish its place for future wireless communication with its promising compactness and extraordinary performance.

Novel, compact, circular-sectored antenna for Ultra-Wideband (UWB) communications

ABSTRACTThis article presents a compact circular-sectored microstrip antenna embedded with circular slots and a sectoral ground plane for enhanced bandwidth and applicable for UWB communications exhibiting an equivalent Fractional Bandwidth of 156.04% (2.5–20.25 GHz) and allows a compactness of about 79.15% using Rogers RT-Duroid 5880 as a substrate for lesser surface wave loss and attaining broader bandwidth. The gain of the antenna ranges from 1.85 to 6.10 dBi throughout the resonant frequency band and the results obtained from measurement are validated to justify the applicability of this antenna for various WLAN and Wi-MAX frequency bands.

Small Frequency Ratio Multi-Band Dielectric Resonator Antenna Utilizing Vertical Metallic Strip Pairs Feeding Structure

In this study a quintuple band rectangular dielectric resonator antenna (RDRA) with a small frequency ratio and small size of 30 mm × 30 mm × 9.813 mm is introduced. The proposed RDRA covers the frequency bands of WLAN (2.4/5.2 GHz), WiMAX (3.5 GHz) and 5G (4.1/4.8 GHz) exploiting TE 10 y , TE 211 x , TE 1δ1 y , TE 111 y , and TE 2δ1 y modes, respectively. A rectangular slot aperture is optimized to serve as a resonator with resonance mode TE 10 y as well as to couple the electric field from microstrip line to the DRA to excite TE 211 x mode. Furthermore, a new feeding approach employing three vertical metallic strip pairs (VMSPs) is proposed to excite further TE 1δ1 y , TE 111 y , and TE 2δ1 y modes in the RDRA. The VMSPs are configured on both sides of the dielectric resonator (DR) along the y - direction to act as vertical electric current sources. The lengths, width, and positions of the VMSPs are carefully determined in order to attain the desired modes. The four RDRA modes have broadside patterns while the slot resonator mode has a pattern like a dipole. Good agreement between both measured and simulated results of the reflection coefficient, radiation pattern, and the gain is achieved.

Broadband Antenna Design With Integrated CB-CPW and Parasitic Patch Structure for WLAN, RFID, Wimax, and 5G Applications

This paper presents a novel CB-CPW wideband antenna design. HFSS software simulations reveal that the proposed design has a semicircle ground structure, transmission line, parasitic ground, CPW, relatively low return loss, broadband effect of 3.3377 GHz (4.8337 GHz-8.1714 GHz), double beam capability at 5.2 GHz, and four-beam capability at 5.5 GHz (5.8 GHz). It is compact in size at only 40 mm × 40 mm × 1 mm. A prototype of the proposed antenna was fabricated and measured to validate the simulated design; the results show a bandwidth of 3.38 GHz (3.95 GHz-7.33 GHz), relative bandwidth of 74%, and maximum gain of 3.87 dBi in the range of 5 GHz to 6 GHz; the prototype also achieves two and four-beam performance. Its working frequency covers WLAN (5.15 GHz-5.25 GHz and 5.725 GHz-5.825 GHz), radio frequency identification RFID (5.8 GHz), and global microwave internet access WiMAX (5.25 GHz-5.85 GHz) frequency bands.

RF energy harvesting prototype operating on multiple frequency bands with advanced power management

&lt;span&gt;Radio Frequency (RF) harvesting seems to be catching up as an alternate energy source whereby RF energy is scavenged from ambient sources and converted into renewable energy in terms of DC power. This converted DC power is then utilized to power up devices that require a low start up power in which eliminates the need for battery replacement. In this paper, a novel RF energy harvesting prototype is presented which consists of two microstrip patch antennas operating on GSM (900MHz) and WIFI (2.4GHz) &amp;amp; WiMAX (2.3GHz) frequency bands with a bandwidth of 220MHz and 10.11MHz respectively to harvest RF signals from ambience. Two matching networks are presented as well to ensure efficient power transfer to load. Rectifiers are designed to transform the RF signals to DC power. The converted DC signals are then combined and fed to a power management circuit which charges a 4.2V NiMh battery and drives a load at a regulated output of 3V.&lt;/span&gt;