Omnidirectional Radiation Pattern Research Articles

A miniaturized triple-band planar antenna combing single-cell metamaterial structure and defected ground plane for WLAN/WiMAX applications

In this paper, a novel miniaturized triple-band planar monopole antenna combing single-cell metamaterial structure and defected ground plane is proposed. The miniaturization and triple-band characteristic of the antenna are achieved by loading the designed multiresonant metamaterial unit cell. Furthermore, a compact annular defected ground structure is proposed and used to improve the bandwidth of the antenna effectively. The presented metamaterial inspired triple-band antenna has a compact size and a simple structure. To verify the performances of the antenna, a prototype is manufactured and measured. The experimental results indicate that the presented antenna has enough operating bandwidth of the 2.38–2.48, 3.37–3.79, and 4.36–6.06 GHz to cover all the desired WLAN and WiMAX operations. And the tested results also demonstrate that this antenna has good omnidirectional radiation patterns and reliable gains in three required bands. Thus, the presented antenna has broad prospects in many wireless communication applications.

A novel automobile antenna for vehicles communication of IoT systems in 5G network

The Internet of vehicles (IoV) is an important part of mobile communication system with the development of Internet of things. A novel multiband automobile antenna is proposed, which can cover all frequency bands for the long-term evolution (LTE), the fifth generation wireless systems (5G), the wireless local area network and the dedicated short-range communication (from 690 to 944 MHz and from 1.46 to 6 GHz). The antenna is designed based on the monopole antenna, and the impedance matching performance of the antenna is improved by loading the toothed capacitor and the impedance matching disk. The simulation results show that the automobile antenna achieves good impedance matching in the working bandwidth and obtains omnidirectional radiation pattern in the horizontal direction. The electric field distribution of the antenna placed on the vehicle roof is simulated to evaluate the network performance of the antenna system in the urban environment. The transmission coefficient of the transceiver system using the automobile antenna is also analyzed based on the electromagnetic simulation results and statistical model. The blind area of mobile communication system is effectively covered with the automobile antenna, which could be used to connect the LTE cell and the IoV system.

Dual-Band Structure-Shared Antenna With Large Frequency Ratio for 5G Communication Applications

A dual-band structure-shared antenna with large frequency ratio is proposed in this letter by integrating two substrate integrated waveguide slot antennas (SIWAs) on the branches of dipole. In the proposed structure, dipole is fed by coaxial connector while SIWAs are fed by two microstrip lines. To improve the stability of the dipole and the isolation among three antennas, microstrip high-pass filter is introduced. Measured results show that the proposed antenna works at 27.3−28.8 GHz with directional radiation pattern and 3.02−5.03 GHz with omnidirectional radiation pattern.

Wearable Dual-Band and Dual-Polarized Textile Antenna for On- and Off-Body Communications

A wearable all-textile microstrip patch antenna (MPA) operating in the dual bands of medical body area network (2.36–2.40 GHz) and WiMAX (3.4–3.6 GHz), is proposed for body-centric communications. The omnidirectional radiation pattern with linear polarization for on-body link and unidirectional radiation pattern with circular polarization for off-body link are achieved by introducing reactance loading into MPA. Notably, two pairs of shorting pins are employed to tune the TM10 mode of MPA and generate a new mode of TM00, and by adjusting the spacing and radii of shorting pins, the required dual-band and dual-mode operation is achieved. Moreover, due to the adoption of textile (i.e., wool felt) as substrate and nylon conductive fabric as conductor, the antenna is flexible, totally conforming to the human body. The proposed MPA, with the dimensions of 70 mm × 70 mm × 2 mm (0.56λ0 × 0.56λ0 × 0.016λ0 at 2.38 GHz), was fabricated and characterized. The measured results show that the reflection coefficient, radiation pattern, and gain of the antenna are slightly affected by structural deformation and human body loading. With merit characteristics, the proposed design can be well applied to wearable medical applications.

A compact printed ultra-wideband filtenna with low dispersion for WiMAX and WLAN interference cancellation

A printed monopole filtenna fed by a co-planar waveguide with U-shaped split slot on patch and circular split ring resonator pairs at the other side of feed is proposed in this letter. The compact filtenna of dimension 0.32λ × 0.215λ (λ denotes wavelength corresponding to 2.68 GHz) is capable of providing large bandwidth from 2.68 to 8.72 GHz with dual frequency notch bands over 3.28–3.84 and 4.95–6.02 GHz, primarily to eliminate the WiMAX and WLAN interferences. The dual notched antenna performances are evaluated by simulation and experimental measurement and compared to those of recently reported ultra-wideband (UWB) notched antennas. The proposed filtenna provides bidirectional E-plane and omni-directional H-plane radiation patterns with gain variation of 2–4.5 dBi and average radiation efficiency of 78% in its pass band. Also the filtenna offers minimal dispersion characteristic as stable group delay response, and linear variation of transfer function (S21) is achieved in its pass bandwidth.

Wearable Dual-Band Dual-Polarization Button Antenna for WBAN Applications

This letter proposes a wearable dual-band dual-mode button antenna for wireless body-area network applications. It covers the 2.45 and 5.8 GHz Industrial, Scientific, and Medical bands. The two operating modes of the antenna are designed to share a common radiator with different functionalities for distinctive communication requirements. The antenna operates from 2.32 to 2.57 GHz as a top-loaded monopole antenna with linear polarization, which is applicable for on-body communications due to its omnidirectional radiation pattern. In contrast, it works as a crossed-dipole antenna in its higher operation band extending from 5.72 to 7.85 GHz, in which it exhibits broadside radiation with circular polarization suitable for off-body communications. The experimental characterization on the fabricated antenna prototype, both in free space and proximity to the human body, proves that the antenna operates as anticipated with dual-band and dual-polarization characteristics for wearable applications.

Low-RCS feature for UWB antenna with band-notch characteristics

This paper presents a new technique to reduce radar cross-section (RCS) of dual-band antennas. In order to show that the proposed method can be applied in various types of monopole antennas, two different patch antennas are designed one of which is fabricated. The primary model of the fabricated antenna without modification is composed of a circular radiator with two pairs of T-shaped strips. To reduce the RCS of the antenna, a half of its radiator that is not connected to the feed line is removed with its substrate. A perfect electric conductor (PEC) wall is designed and located in front of the remained half patch to generate an image of it. The results indicate that the proposed structure offers an omni-directional radiation pattern over a wide frequency range and a very wide impedance bandwidth with a WLAN band rejection as well as an in-band and out-of-band RCS reduction.

Defective ground structure and complimentary split ring resonator loaded compact wideband antenna for radiolocation applications

A wideband compact antenna with wo Bandwidth enhancement techniques intended for radiolocation applications is presented. Defective ground structure (DGS) is used to enhance the bandwidth and complimentary split ring resonator (CSRR) has been used to generate the bandwidth at the lower frequency of the antenna which brings compact nature. A coax feed patch antenna radiating at X-band frequency of 10 GHz is loaded with DGS and CSRR. Proposed antenna with a bandwidth of 3.4 GHz has shown a considerable enhancement in the antenna bandwidth when compared with the antenna with CSRR alone which is having a bandwidth of 1.15 GHz and a basic patch antenna whose bandwidth is 0.91 GHz. Proposed antenna is having omni directional radiation pattern with a gain of 5.01 dB and without any null in the coverage area. A great increase in the current fields can be observed that the field currents by loading the patch and ground with CSRR and DGS respectively. The patch currents have increased from 2.76 v/m to 3.25 v/m and the ground currents have increased from 0v/m to 2.45 v/m. Proposed antenna has been realized and its performance is measured using vector network analyzer, a near match in between the simulated result and measured result is observed.

A multi-slotted antenna for LTE/5G Sub-6 GHz wireless communication applications

AbstractThis paper presents a low-profile multi-slotted patch antenna for long term evolution (LTE) and fifth-generation (5G) communication applications. The studied antenna comprised of a stepped patch and a ground plane. To attain the required operating band, three slots have been inserted within the patch. The insertion of the slots enhances the capacitive effect and helps the prototype antenna to achieve an operating band ranging from 3.15 to 5.55 GHz (S11 ≤−10 dB), covering the N77/N78/N79 for sub-6 GHz 5G wireless communications and LTE bands of 22/42/43/46. The wideband antenna presented in this paper offers omnidirectional stable radiation patterns, good gains, and efficiency with a compact size which make this design an ideal contender for wireless fidelity (WiFi), wireless local area network (WLAN), LTE, and sub-6 GHz 5G communication applications.

A simple printed antenna with broadband property and omnidirectional radiation patterns of wire dipole

A simple printed antenna with broadband property and omnidirectional radiation patterns of wire dipole

A Multiple Narrow Band Antenna for Detection of Discharge‐Emitted Electromagnetic Waves for Insulation Diagnostic

Partial Discharge (PD) detection is an effective tool to diagnose the insulation condition of high voltage (HV) equipment. Among detection methods of PD, the ultra‐high frequency (UHF) method is distinguished by high sensitivity and safety operation. However, the UHF band includes many communication and broadcasting line spectral frequencies, which can be interference against the UHF method. From the point of view of the reduction of interferences, the authors proposed the multiple narrow band (MNB) antenna, which can detect PD signals with high sensitivity and eliminate the line spectral noise frequencies. In this paper, a new MNB antenna was evaluated based on fundamental properties and fabricated, then applied to detect discharge signals emitted from breakdown phenomena. The results demonstrated that the fabricated MNB antenna had a good omnidirectional radiation pattern and similar sensitivity with a standard wide‐band Horn antenna. © 2020 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Bandwidth enhanced miniaturized slot antenna on a thin microwave laminate

This paper presents the design of a novel printed slot antenna with broadband characteristics. The antenna size reduction is achieved by the bisection method. The antenna is developed on a thin low loss substrate. A reference annular slot antenna of dimension 30 × 30 mm2 is reduced to 15 × 15 mm2 which is 75% smaller than the reference monopole antenna. The miniaturized slot antenna provides broadband characteristics extending its operation from 3 GHz − 8 GHz making the antenna suitable for terrestrial communications. The miniaturized antenna preserves the omnidirectional radiation pattern of the reference slot antenna. The prototype antenna is fabricated and tested for S-parameter characteristics and radiation characteristics. The proposed miniaturized antenna offers 91% bandwidth with |S11| ≤ −10 dB. The measured gain of the antenna varies from 2.48 dBi to 4.98 dBi with peak gain at 7 GHz. The antenna exhibits good impedance matching and radiation characteristics making the antenna suitable for modern communication systems such as wireless sensor nodes, Internet of Things (IoT), wireless monitoring systems, etc.

Compact filtering antenna using asymmetric CPW-fed based CRLH structure

Compact filtering antenna using composite right/ left-handed (CRLH) transmission line structure is presented in this paper. It utilizes a simplified asymmetric coplanar waveguide (CPW) feeding method. Initially, a bandpass filter has been designed with a circular interdigital capacitor, meander line and rectangular patches with asymmetric CPW feeding. The filtering antenna structure has been designed by replacing the rectangular patch and coupling at load side (Port-2) of the designed filter with L-shaped patch, which acts as a radiating element. The resonance frequency can be controlled by the series parameter due to shorted boundary condition of the structure. The designed filtering antenna resonates at 3.4 GHz with 10-dB impedance bandwidth of 23.5%. It provides a nearly flat gain response within the passband by the average value of 2.5 dB along with two radiation null at 2.1 GHz and 4.5 GHz. The total size of the designed structure is 0.39λg × 0.26λg at the resonance frequency (3.4 GHz) of the working band. It gives an omnidirectional radiation pattern at the resonance frequency. The designed prototype is fabricated and measurements are done for validation of simulated results and the filtering antenna is made useful for sub-6 GHz of 5G (3.3–3.6 GHz) applications.

Broadband T‐bar fed slot antenna array with stable horizontally polarized omnidirectional radiation

A broadband horizontally polarized omnidirectional antenna array is proposed, which consists of a circular array of four identical broadband T-bar fed cavity-backed slot antenna elements and a 1-to-4 power divider. The proposed omnidirectional antenna array has a compact diameter of only 0.44λ0, a broad bandwidth of 75.9% (450-1000 MHz) and a favorable omnidirectional radiation pattern in the azimuth plane with a gain variation below 3 dB in the operating band. Moreover, the cavity-backed structure makes the proposed antenna array hardly affected by metal environment and the all metal construction allows for high-power applications, and the reserved cable channel behind the cavities of the antenna elements ensures the extensionality and stability of the proposed array when longitudinal array expansion is needed. Design procedures of the proposed antenna array have been described in detail, simulations and measurements of the proposed antenna array have also been carried out to validate its performance in this article.

A Study on Dual-band Microstrip Rectangular Patch Antenna for Wi-Fi

This paper presents the design of a dual-band microstrip patch antenna for Wi-Fi that operates at 2.5 GHz and 5.8 GHz. The antenna contains a rectangular patch with two rectangular slots. The first slot is incorporated in the patch while the second slot is incorporated in the ground plane. The antenna is based on a microstrip fed rectangular patch printed on the FR-4 epoxy substrate with a dielectric constant of 4.4 and a thickness of 1.6 mm with patch size 24 mm × 21 mm. The simulated result shows that the realized antenna successfully works on dual-band and subsequently achieves a bandwidth of 100 MHz and 200 MHz as well as the return loss about -29.9 dB and -15.16 dB for 2.5 GHz and 5.8 GHz respectively. A stable omnidirectional radiation pattern is observed in the operating frequency bands. The antenna meets the required specifications for 802.11 WLAN standards.

A planar triple-band monopole antenna loaded with an arc-shaped defected ground plane for WLAN/WiMAX applications

AbstractIn this paper, a new printed triple-band planar antenna combing two different modified monopoles and an arc-shaped defected ground plane is proposed and studied. The used two simple monopoles consist of a rectangular ring and a rectangular patch attached a straight metal strip. And a compact arc-shaped defected ground structure is proposed and used to excite higher resonance frequency and improve the impedance matching of the antenna at lower and middle resonance frequencies. The main radiation element of the proposed antenna composed of only two simple monopoles can support three omnidirectional radiation modes at three desired bands. To indicate the working mechanism of the antenna, the design process is illustrated and the parametric studies are carried out. The experimental results of the fabricated prototype confirm that the triple-band antenna has better radiation efficiencies, appropriate gains, and stable omnidirectional radiation patterns. And the tested results also show that the antenna can provide enough bandwidths of 2.35–2.52, 3.2–4.16, and 5.13–5.87 GHz to cover all the desired 2.4/5.2/5.8 GHz WLAN and 3.5/5.5 GHz WiMAX operations. Moreover, the presented antenna has a very simple structure. Thus, the designed antenna has high practicality and broad prospects for WLAN and WiMAX applications.

Miniaturization of Omnidirectional Cavity Antennas Using Substrate-Integrated Impedance Surfaces

This communication presents a compact cavity antenna with horizontally polarized omnidirectional radiation pattern. The dimension miniaturization of an omnidirectional resonant cavity is achieved by loading the capacitive substrate-integrated impedance surface (SIIS). Specifically, the SIIS is composed of a row of blind vias that are periodically arranged near the antenna's radiating aperture, effectively providing a shunt capacitance that can be controlled by the insertion depth, period, and diameter of blind vias. The dispersion of the omnidirectional cavity antenna is theoretically studied and the explicit design formula is derived. Our results report that loading the capacitive SIIS can significantly reduce the size of an omnidirectional cavity antenna (52.4%). As a proof of concept, a prototype was fabricated and characterized, with a good agreement between the measurement and simulation results. The results also show that omnidirectional radiation patterns can be maintained well when the operating frequency is tuned, with the realized gain slightly fluctuated between 2.7 and 3.2 dBi. The proposed antenna exhibits potentials in volume-limited omnidirectional wireless communication systems.

Ruggedized Surface-Mount Omnidirectional Antenna for Supersonic Aerial Platforms

A rugged metal protected antenna that produces an omnidirectional radiation pattern is proposed in this letter. The omnidirectionality is achieved by using a cavity enclosed printed circuit board (PCB) with λ/4 transformers and ground shortening pins combination. The slotted cavity filled with ablative material is designed to maintain the radiation characteristics of the enclosed PCB and provide strength for the antenna arrangement, which can be effectively used on high-speed aerial platforms. The simulated and measured results demonstrate that the proposed antenna possesses a stable omnidirectional radiation pattern; its horizontal gain is higher than -1.5 dB, the azimuthal gain ripple is within ±0.7 dB, and the antenna efficiency exceeds 85% over the entire operational frequency band. In addition, the conformal, tapered, nonprotruding, low-profile, and dc-grounded design makes winged antennas a superior candidate for supersonic (Mach > 1) airborne applications.

Mode Compression Method for Wideband Dipole Antenna by Dual-Point Capacitive Loadings

In this communication, a dual-mode compression method is proposed for wideband applications of thin dipole antennas. In this method, only two points along the thin dipole antenna are properly found and loaded by two capacitors, lumped or distributed. At these two loading points, there are current nulls of the third mode of the dipole. With two capacitive loadings, an obvious upshifting of the first mode's resonant frequency is observed but with little effects on the third mode. By compressing the first and third modes, an enhancement of the antenna bandwidth is achieved. In addition, a parallel line is used as a transformer for impedance matching. A prototype of the design has been fabricated and tested. The measured results agree well with the simulated ones. In the thin structure of 1.01 × 0.09 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> (λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> is the free space wavelength at the center frequency), a wide bandwidth from 1.88 to 3.18 GHz (51.4%) is achieved, performing an omnidirectional radiation pattern with gain of 2.0-4.0 dBi in azimuthal plane.

Meandered low profile multiband antenna for wireless communication applications

The compact slotted antenna having offset feed radiating in the multi-frequency bands is proposed. The antenna geometry comprises of a vertical and horizontally coupled slotted structure at the top with a complete ground plane at the bottom to achieve the proposed application bands. The patch is patterned on the FR4 substrate having a dielectric constant of 4.4 and loss tangent of 0.008. The antenna has an overall dimension of 0.18λ × 0.15λ mm2 (f = 1.52 GHz) with offset fed which is optimized to achieve 50 Ω impedance matching. The proposed compact antenna resonates in pentaband frequency bands which includes 1.52–1.60 GHz for GPS (ISM band in India), 2.97–3.02 GHz for Radio frequency identification and detection, mobile communication, logistics, manufacturing, transportation and healthcare, 3.73–3.84 GHz for Amateur Fixed Mobile except aeronautical mobile (R), 4.42–4.52 GHz for radio communications, TransferJet USB Adapter (Toshiba Corporation), and 4.83–4.96 GHz for Aviation Private Land Mobile applications. The proposed antenna has demonstrated a decent gain ranging from 1.07 to 3.92 dBi having omnidirectional and bidirectional radiation patterns, hence, making it suitable for various wireless applications.