Omnidirectional Radiation Pattern Research Articles

Design of compact fractal patch antenna for X/Ku/K‐band applications

SummaryThis paper presents a fractal‐based compact new monopole antenna for wideband applications. The miniaturization has been achieved by incorporating Minkowski and Koch‐snowflake fractals. The proposed antenna design is etched on top of Rogers RT/5880 dielectric material with a dimension of mm2. The antenna is designed, analyzed, fabricated, and tested in the laboratory. The proposed geometry operates over a 8.62–22.40 GHz with fractional bandwidth (FBW) of 88.84% and VSWR is less than 2. The proposed monopole antenna exhibits nearly omnidirectional radiation patterns over the entire resonating band with a gain of 1–2.91 dBi and a radiation efficiency of more than 60.5%. Also, the measured results of the prototype make an excellent agreement with the simulated counterpart. Further, the antenna gives good time‐domain characteristics. Therefore, the proposed miniaturized antenna can be used in X/Ku/K‐band applications.

UWB Microstrip Patch Antenna Design for Energy Harvesting Applications

RF energy harvesting systems, which are the receiver part of Wireless Power Transfer (WPT), have gained significant development in recent years. For maximum energy acquisition over a wide frequency range, such as to provide power to small handheld devices like cell phones, tablets, smart watches, and other smart devices, wideband and compact antennas are desired. RF systems are expected to cover different frequency bands, such as 2.4 GHz, 5.1 GHz, 5.8 GHz (Bluetooth/Wi-Fi), 2.3 GHz, 2.5 GHz, 3.5 GHz, 5 GHz (WiMAX), for energy harvesting. For such an RF harvesting system, the antenna is desired to have a wide bandwidth, good gain, and an omnidirectional radiation pattern. Energy harvesting devices refer to designs that integrate production and storage. For instance, radio frequency energy sources contain a large amount of electromagnetic energy in the environment, and with RF energy harvesting systems, a portion of this electromagnetic energy can be collected and converted into usable DC voltage. Microstrip patch antennas are very good alternatives for energy harvesting applications because they are cost-effective, compact in size and weight, flat in structure, and highly repeatable. This paper presents a microstrip patch antenna with a bandwidth of 3.9 GHz in the 3.4 to 7.3 GHz range for UWB applications. The antenna design has a gain value of 3.28dBi at the numerically calculated resonance frequency of 4.9 GHz and generally covers frequencies used for electronic device communication such as Wi-Fi 5 GHz and WiMAX. The proposed antenna design has gain values that are allowed to be used for RF energy harvesting applications.

A Dual-Polarized Omnidirectional Metasurface Antenna Designed via Characteristic Mode Analysis

A low profile dual-polarized (DP) omnidirectional metasurface antenna is proposed in this letter. By conducting characteristic mode analysis (CMA) on a metasurface, one mode with vertically polarized (VP) omnidirectional radiation pattern and another one with horizontally polarized (HP) counterpart are first found. To allow for an easy excitation, a method which can independently manipulate both modes is then developed. After optimization, the VP modal current concentrates at the center of the metasurface, while the HP modal current mitigates to the edges of the metasurface. As a result, the two modes can be excited simultaneously with a simple feeding strategy, namely, a central probe is used to excite the VP mode, and four slots under the four edges of the metasurface are used to excite the HP mode. To verify the design, a prototype is simulated, fabricated, and measured. The results show that the proposed antenna achieves a DP omnidirectional radiation with a wide bandwidth of 39.4% and high ports isolation of 32 dB.

Triple Band-Notch UWB Antenna Embedded with Slot and EBG Structures

In this paper, a planar, compact pentagonal shaped ultrawideband antenna of microstrip line fed offering triple band-notched characteristics response is proposed and investigated. Triple band-notch response can be achieved by creating two inverted U-shaped slots of different size in pentagonal patch, and also electromagnetic band gap structure of hexagonal shape is created near the feed line of UWB antenna. To implement the proposed antenna, RT/DUROID 5880 substrate of 1.6 mm thickness is used. The designed antenna was successfully simulated, developed, and manufactured. The dimension of the suggested antenna is 36 mm × 33 mm × 1.6 mm and has a bandwidth of 3.1–10.6 GHz with a magnitude of S 11 < − 10 dB , the maximum pass band gain of 4.6 dB and with the exception of the 4.0–4.4 GHz (C-band satellite communication), 5.2–5.8 GHz (WLAN), and 8.0–8.25 GHz (X-band) frequency bands. The suggested antenna has a good return loss, a virtually omnidirectional radiation pattern, and a constant gain throughout operation.

Design of NULLMAC Protocol for Mobile Ad Hoc Network Using Adaptive Antenna Array

Usually, omnidirectional radiation pattern antenna is used in the mobile ad hoc network (MANET) which causes neighbor node interference, consumes more power, and supports only limited range of transmission. To overcome these problems, smart antennas are used. A lot of medium access control (MAC) protocols are proposed using smart antennas. Existing works addressed various problems such as hidden terminal problem, hidden beam problem, deafness of nodes, and head of line blocking problem. However, certain factors including determination of weight vector and conveying it to the neighbor nodes for distortion-free transmission are not considered. In this study, nullifying MAC (NULLMAC) framework is proposed using an adaptive antenna array (AAA) for improving network performance in MANET. NULLMAC framework uses channel information for achieving high throughput and spatial reuse through integrated physical and MAC layer. Before the transfer of data packets, the receiver initially determines its weight vector and conveys it to the transmitter through control packets. Then, the transmitter computes its weight to nullify the dynamic receivers present in the neighborhood region to find the desired receiver. Beamformer weights are determined through channel coefficients between a transmitter-receiver pair to establish distortion-free transmission. Extensive simulations are performed using OPNET integrated with MATLAB. NULLMAC framework achieves 27.22% more throughput and 40.46% increase in signal-to-noise ratio.

Low cross polarized leaf shaped broadband antenna with metasurface as superstrate for sub 6 GHz 5 G Applications

This article presents the design, circuit model analysis, and realization of a metasurface-based novel leaf-shaped antenna for sub 6 GHz 5 G NR frequency bands like n77 (3.3–4.2 GHz), n78 (3.3–3.8 GHz), n79 (4.4–5 GHz), and n90 (2.4–2.6 GHz) applications. Primarily, a leaf-shaped microstrip planar antenna is designed and provides a broad impedance bandwidth of 77.43% (2.2–4.98 GHz), a peak gain of 4.51 dBi, and a high radiation efficiency of 94.16%. The planar antenna is integrated with a 5 × 3 elements periodic metasurface (MS) array to enhance radiation performance. Both the radiating leaf planar and the MS layer have been designed on a low-cost FR4 epoxy substrate, and equivalent circuit models have been developed for both successively to validate the EM simulated results. The overall dimensions of the planar antenna with MS layer are 0.45 λ0 × 0.27 λ0 × 0.108 λ0, (λ0 corresponds to lowest resonant frequency f=2.7 GHz). The tested antenna with MS superstrate covers a broad range of operating frequencies from 2.29 to 4.78 GHz (2.49 GHz) with a − 10 dB impedance fractional bandwidth of 70.43% and has an excellent reflection coefficient of more than − 35 dB for the entire operating band. The experimental peak gain and higher radiation efficiency are 8.76 dBi and 96.6%, respectively. Moreover, all these parameters are extremely high in single-layer planar antennas, including the stable omnidirectional radiation pattern with very low cross-polarization of − 53.34 dB.

Split ring resonator inspired defected ground plane dual operating band antenna for wireless LAN and RFID applications

Defected ground structure (DGS) using an array of the three split ring resonators inspired antenna for the Wireless Local Area Network(WLAN) and RFID sensor is proposed in this manuscript. The complete physical measurement for the proposed antenna is 50 X 40 mm2 (at lower operating frequency). The defected ground plane structure along with the inclusion of the square split ring resonators (SRRs) in the ground plane helps in gain and bandwidth improvement. 1 × 3 split ring resonator array is used to make the existing ground plane to be defected. The cost effective FR – 4 materials is used as a substrate for the fabrication with the standard thickness of 1.6 mm. The resonance frequencies are at 2.4 and 5.8 GHz having the average gain 2.65dBi. The impedance bandwidths for both the frequencies are 5.0 % (2.31 to 2.49 GHz) and 3.9% (4.9 to 6.1 GHz). The dipole and omni directional radiation patterns, overall gain and efficiency of around 75% make the antenna most practically possible for the RFID and WLAN devices.

Surface current engineering enabled broadband monopole patch antenna with low profile

Antennas with broadband radiation and small-size are highly required in wireless communication system. The trade-off relation between bandwidth and size became a difficulty when it comes to miniaturized antenna design. A method of realizing antenna miniaturization and bandwidth enhancement at the same time is needed. Monopole antennas are the most common used one in the devices of Internet of Things, Internet of Vehicles, and wireless access points et al. In this paper, a wideband low-profile top-loaded patch monopole antenna based on surface current engineering is proposed. The topology combines a center-fed circular patch with inductive vias. The patch is designed with patterns, which consists of four concentric annular rings and some strips in radial direction. In this way, three resonances are generated, and the pattern is optimized to bring three resonances close to each other. The number of the strips is specially designed to bring three resonances close to each other. By loading the inductive vias on the outermost rings, connecting to the ground, the resonance at low frequencies can be enhanced, as a consequence of the optimized impedance matching. The field distribution is analyzed to verify the operation principle. A prototype is fabricated, and the measured results agree well with the simulated ones. The relative −10 dB bandwidth is 69% and the omnidirectional radiation pattern is stable in the operating band. The antenna achieves a rather wideband radiation while maintaining a low profile. The method of antenna miniaturization and bandwidth enhancement based on surface current engineering paves the way for antenna design in low-profile ultra-wideband applications.

Highly Compact 4 × 4 Flower-Shaped MIMO Antenna for Wideband Communications

This paper introduces an MIMO antenna with a highly compact size of 30 mm width and 30 mm length. Four symmetrical MIMO antenna radiators are utilized with decoupling stubs in the top and bottom planes of the substrate to improve the isolation level. The simulated and measured outcomes are validated to investigate the impact of the suggested MIMO antenna for wideband applications. The suggested MIMO antenna has an impedance matching less than −10 dB from 5.8 GHz up to 11 GHz, and the isolation between the four radiators exceeds 20 dB over this band. Moreover, the antenna provides an envelope correlation coefficient not exceeding 0.004, a diversity gain above 9.97 dB, and a mean effective gain of ≤−3 dB over the achieved frequency range. The suggested MIMO antenna exhibits a nearly omnidirectional radiation pattern in one plane and a bi-directional radiation pattern in the other plane with an acceptable average value of the realized gain (4 dBi) over the achieved frequency band. A comparison with the state-of-the-art is tabulated to show the distinct performance of the suggested MIMO antenna for wideband applications.

Wing Conformal Load-Bearing Endfire Phased Array Antenna Skin Technology

In this article, a phased array antenna skin is proposed for conformally assembling scenarios and wide scanning applications. Planar inverted F antenna (PIFA) is used as a radiation element of the proposed array due to its low profile and omnidirectional radiation pattern. The PIFA element is conformally assembled in a wing of an aircraft and is designed and fabricated with the technology of composite material, which makes the PIFA element load bearing. The endfire beam synthesis is also investigated, and the proposed array supports wide-angle beam scanning in both forward and backward regions. An array of 240 PIFA elements are designed, simulated, fabricated, and experimentally tested. The fabricated sample is able to bear an overload of 1 g in the mechanical test, and all the electronic experiment results agree well with the simulation data.

Wide Bandwidth Ratio of 10-to-1 CPW-Fed Whip Antenna With Improved Radiation Patterns

In this communication, a novel compact single whip wideband antenna with an improved omnidirectional wideband antenna is proposed. First, a single whip antenna is designed on a thin flexible printed circuit (FPC) with a tapered coplanar waveguide feed line. This proposed antenna shows a wide impedance matching performance in a frequency range from 194 to 2124 MHz with a bandwidth ratio of 10:1, while a measured return loss is better than 10 dB within the desired passband. The single whip antenna has demonstrated an ultrawide bandwidth with satisfactory radiation properties in the lower frequency band. However, the omnidirectional radiation pattern deteriorated in the higher frequency band. Three whipped antennas are codesigned to form an improved omnidirectional radiation pattern. Finally, the measured performance of the fabricated antenna shows a good agreement with that obtained through simulation results.

Antennas for Licensed Shared Access in 5G Communications with LTE Mid- and High-Band Coverage.

Two novel antennas are presented for mobile devices to enable them to access both licensed shared access (LSA) bands (1452-1492 and 2300-2400 MHz) and all the long-term evolution (LTE) mid (1427-2690 MHz) and high (3400-3800 MHz) bands, together with the GSM1800, GSM1900, UMTS, and 3.3 GHz WiMAX bands. These antennas do not require any passive or active lumped elements for input impedance matching. One of them is a dual-band antenna and the other is a wideband antenna. Both antennas have high efficiency in all the LSA bands, as well as the mid- and high-LTE bands, and nearly omnidirectional radiation patterns in the mid band. In the high band, the radiation patterns of the wideband antenna are less directional than those of the dual-band antenna. The wideband antenna was fabricated and tested and the measurements demonstrated that it had good wideband performance in a wide frequency range from 1.37 to 4 GHz, covering all the above-mentioned bands.

A Christmas Tree-Shaped Quadband Compact Antenna with Triple Slots for Various Wireless Technologies

A compact, coplanar waveguide (CPW)-fed multiband antenna is developed and analyzed in this paper for quad-band applications. Christmas tree-like monopole antennae with three symmetric slots are designed on a low-cost FR4 epoxy substrate with the overall dimensions of 0.312λ 1 × 0.364λ 1 × 0.0083λ 1 where λ 1 is the wavelength corresponding to the lower cut-off frequency. Three rectangular-shaped slots of different dimensions are etched on the three triangular-shaped stacked patches to enhance the current carrying path due to which the proposed antenna resonates at the required frequency bands. Different antenna parameters such as reflection coefficient (S 11), gain, radiation efficiency, surface current, radiation pattern, group delay and magnitude response of transfer function (S 21) are analyzed for inspecting the antenna performance. The quad-band antenna offers measured bandwidths of 3.1–3.9 GHz (22.86%), 5.46–5.98 GHz (9.1%) 9.76–11.74 GHz (18.42%) and 17.55–19.25 GHz (9.24%). The antenna shows nearly omnidirectional radiation patterns in all resonating bands with the highest gain of 4.5 dBi and measured radiation efficiency greater than 70% in all the bands. The antenna also offers stable group delay response and linear S 21 response in its operational spectrums. All these characteristics ensure the antenna’s applicability in IEEE 802.16 WiMAX band, 5.5 GHz Wi-Fi band, 5.8 GHz ISM band, terrestrial broadband, radiolocation and earth explorer satellite applications.

A Miniaturized Dual-Band Short-Ended ZOR Antenna with Backed Ground Plane for Improved Bandwidth and Radiation Efficiency

This paper presents a miniaturized planar dual-band short-ended metamaterial antenna with the backed ground plane to improve antenna bandwidths and radiation characteristics. The proposed dual-band metamaterial (MTM) antenna has been made up of the composite right- or left-handed transmission line (CRLH-TL) concept. Here, the backed ground plane has been employed to generate an extra coupling capacitance (CC), which shifts the ZOR frequency in the lower band while also improving ZOR matching and increasing the impedance bandwidth of the higher-order mode. In this proposed MTM antenna, interdigital capacitance (IDC) has been used in place of a simple series gap, which shifts the higher-order impedance bandwidth into a lower frequency band for second-band Wi-MAX applications (3.3–3.7 GHz). The proposed antenna offers a short-ended MTM, and hence the ZOR frequency is controlled by a series of LC lumped parameters. The proposed antenna offers dual-band behavior with measured −10 dB impedance bandwidths of 5.55% and 41.57% at centered frequencies of 2.70 GHz and 4.33 GHz, respectively. The overall electrical size of the designed antenna is 0.225λ0 × 0.144λ0 × 0.0144λ0 at ZOR (f0 = 2.70 GHz), where λ0 is the free space wavelength; therefore, it is applicable for different Wi-MAX application bands (2.5–2.7 GHz/3.3–3.8 GHz). Furthermore, the proposed dual-band MTM antenna provides compactness, low loss, stable gain, and radiation efficiency, and also offers omnidirectional radiation patterns in the E-plane and dipolar type radiation patterns in the H-plane, respectively.

A novel UWB flexible antenna with dual notch bands for wearable biomedical devices.

This study presents a novel UWB flexible antenna with dual band-notched design for wearable biomedical devices. The proposed antenna is designed on Kapton Polyimide-based flexible substrate. This includes a CPW fed circular and triangle structure. The dual notched bands are realized by using two triangular-shaped spiral slots defected ground structures. The first notched band (2.4-3.7GHz) is generated for rejecting WLAN and WiMAX, the second notch (5.15-5.725GHz) is generated for rejecting HyperLAN/2. The designed UWB antenna has approximately a bandwith of 159% (2.05-14GHz) in simulation. Thus, the designed UWB antenna meets FCC standards. The antenna has an omnidirectional radiation pattern with a maximum gain of 12.7dB in 8.4GHz. The proposed antenna is fabricated with the low-cost airbrush printed technique. In this technique, a higher gain value is obtained by controlling the thickness of the conductive layer. Effect of flexibility on the antenna performance is tested for different configurations in the simulation and anechoic chamber environments. According to the results obtained, the overall performance is not affected except for the shift in frequency. Since the antenna has a UWB structure, the frequency shift that occurs in bending is at a tolerable level. The proposed UWB antenna is suitable for wearable biomedical devices, with a high UWB performance.

Design and analysis several band antenna for wireless communication

This article describes the construction of a dual-band planar monopole antenna. A microstrip patch antenna with a feedline impedance of 50 ohm and a patch composed of G-shaped and inverted L-shaped strips is used to make the suggested antenna ultra wideband for frequencies ranging from 3.1 to 10.6 GHz. In order to design the antennas, we need to know the dimensions 40x40x1.6 mm3 and the thickness of the ground plane (0.035 mm) (5.2 GHz). There is a method of altering the present distribution by introducing slots. the proposed worldwide interoperability for microwave access (WiMAX) and wireless local area network (WLAN) bands, with a peak gain of 5.2% and an omnidirectional radiation pattern, suitable for ultra wide band (UWB) were shown to be viable.

Design of an axial mode helical antenna with buffer layer for underwater applications

<span lang="EN-US">Recently, there is an increasing demand for high-speed wireless communication network for short-range underwater communication. From previous research, most underwater antennas produced omnidirectional radiation pattern which has lower antenna gain. There are a few considerations that need to be taken if the antenna is designed to operate in water environment. This paper discusses the electromagnetic properties which affect the underwater antenna design. Physical properties such as electrical permittivity and conductivity of water contribute significant effect to the size of the antenna as it influences the behavior of electromagnetic signal that propagates in water. In this study, an axial mode helical antenna with waterproof container is presented which operates at 433 MHz. The axial mode helical antenna has circular polarization and is suitable to support wireless application which is surrounded by some obstruction. The proposed antenna produces a bidirectional radiation pattern by placing it into a waterproof casing. Good agreement between the simulation and measurement results validates the concept. However, a little discrepancy between the simulated and measured results may be attributed to the noise originated from the equipment and the environment.</span>

A Miniaturized Tri-Wideband Sierpinski Hexagonal-Shaped Fractal Antenna for Wireless Communication Applications

This paper introduces a new tri-wideband fractal antenna for use in wireless communication applications. The fractal manufactured antenna developed has a Sierpinski hexagonal-shaped radiating element and a partial ground plane loaded with three rectangular stubs and three rectangular slits. The investigated antenna has a small footprint of 0.19λ0 × 0.24 λ0 × 0.0128 λ0 and improved bandwidth and gain. According to the measurements, the designed antenna resonates throughout the frequency ranges of 2.19–4.43 GHz, 4.8–7.76 GHz, and 8.04–11.32 GHz. These frequency ranges are compatible with a variety of wireless technologies, including WLAN, WiMAX, ISM, LTE, RFID, Bluetooth, 5G spectrum band, C-band, and X-band. The investigated antenna exhibited good gain with almost omnidirectional radiation patterns. Utilizing CST MWS, the performance of the suggested Sierpinski hexagonal-shaped fractal antenna was achieved. The findings were then compared to the experimental results, which were found to be in strong agreement.

Compact multiband monopole antenna design for IoT applications

In this work, a miniaturized quad-band monopole antenna design is presented for IoT applications. The proposed antenna comprises simple quarter-wavelength I-shaped, an inverted L-shaped, meander lines monopole radiators with microstrip feed line, tapered ground plane having dimension of and fabricated on an FR4 substrate. The radiation characteristics, such as reflection coefficient, VSWR, gain, efficiency, and radiation patterns, are analyzed from simulation and measurement results. The proposed quad-band antenna resonates at 1.8 (1.7–1.96) GHz, 2.4 (2.26–2.47) GHz, 3.35 (3.1–3.7) GHz, and 5.4 (5-5.65) GHz for GSM, WLAN, 5G, WiMAX applications respectively. Further, the proposed antenna has a fractional bandwidth of 14.4% at 1.8 GHz, 8.75% at 2.4 GHz, 17.9% at 3.35 GHz and 12.03 % at 5.4 GHz. It also exhibits omnidirectional radiation pattern with a gain of 1.5, 1.75, 2.5, and 3.7 dbi at 1.8, 2.4, 3.35, 5.4 GHz respectively and >75% total efficiency at its operating bands. The suitability of the designed antenna for IoT applications is validated through the hosting device model with copper sheet and plastic housing. The simulation and measurement results are having good agreement.

Fractal Sectoral Monopole Antenna for UWB Band Applications

This paper proposes a fractal monopole antenna based on a sectoral-shaped patch. To improve thegain of the proposed antenna over a larger bandwidth, the matching was enhanced by attaching two rectangular stubs to the feeding line. The antenna, which is built on an FR4 epoxy substrate with εr =4.3 and a loss tangent of 0.018 has a compact size of 28 mm×31 mm×1.6 mm. The antenna covers the UWB range and extends to about the 22 GHz frequency, as well as offers omnidirectional radiation patterns. The optimized configuration was fabricated and tested. The impedance bandwidth of the proposed antenna is about 155% with a reflection coefficient better than −10 dB and has a maximum gain of nearly 4 dBi with a relatively stable omnidirectional radiation pattern.