Pair Of L-shaped Slots Research Articles

Investigation of dual-band antenna with low-SAR characteristics for bidirectional brain-machine interface applications

In this paper, we propose an innovative dual-band printed monopole antenna (PMA) for bidirectional brain-machine interface (Bi-BMI) application. The proposed antenna configuration contains of a square radiator with a pair of rectangular slots and an inverted U-shaped slot and a truncated ground plane with a pair of L-shaped slots, which provides two usable radiating bands for down-link data transferring around 2.3–2.5 GHz and for up-link data transferring 3.21–9.03 GHz. By inserting two rectangular slots surrounded by a modified inverted U-shaped slot with modified dimensions on the radiating square patch and also by cutting two L-shaped slots, new resonances are created and therefore much wider impedance bandwidth can be generated at both lower and higher bands. Despite recently reported antenna designs in the literature, the proposed antenna demonstrates wideband radiative characteristics even at higher frequencies, and also the specific absorption rate (SAR) level in 1 mW input power case is satisfactory less than 0.4 W/kg in the whole radiating band. The designed antenna has a compact configuration and small size. Simulated and measured S-parameter and radiation patterns results are demonstrated to confirm the utility of the designed antenna configuration for brain machine interface application.

A Triband SIW Cavity-Backed Differentially Fed Dual-Polarized Slot Antenna for WiFi/5G Applications

A tri-band differentially fed dual-polarized slot (DFDPS) antenna is developed for indoor WiFi/5G wireless communications. The triband antenna is made up of two crossed slots with four pairs of L-shaped slots. The lower and higher bands are generated by the crossed slots, and the middle band is attributed to the L-shaped slots. Eight shorting pins are introduced for improving the impedance matching for all the three bands. A substrate-integrated waveguide (SIW) cavity is employed to back the antenna for unidirectional radiation. Two orthogonal feedlines are applied to differentially feed the antenna for dual polarization. The antenna has a low-profile of about $0.054~\lambda _{\mathbf {2.4}}$ , where $\lambda _{\mathbf {2.4}}$ is the wavelength at the lowest frequency of 2.4 GHz in free space. It is shown that the triband antenna can operate in three bands of 2.4–2.51, 3.29–3.6, and 4.8–5.05 GHz with good unidirectional patterns.

Bandwidth Enhancement of a Wide Slot Antenna Using Fractal Geometry for UWB Application with Multiple Notched Bands

In this paper a combination of rectangular and elliptical fractal geometry is applied on a regular hexagonal wide slot antenna fabricated using a FR4 substrate to obtain ultra wide band (UWB) operation. The bandwidth enhancement of the wide slot antenna due to this fractal curve is studied in a step by step manner and the corresponding mathematical analysis is also presented. The comparison of the proposed fractal geometry with the existing fractal geometries is also exhibited. Multiple input multiple output performance of the proposed UWB antenna is also analysed. Two pairs of L-shaped slots are etched on the ground plane and a metallic ring is inserted inside the slot to produce triple band notch characteristics at 3.98 GHz, 5.56 GHz and 7.94 GHz. These three notch bands can avoid interference with existing WIMAX, downlink of C-band satellite communication, WLAN and uplink of X band satellite communication. The proposed band notched UWB antenna exhibits acceptable radiation characteristics with satisfactory gain, high radiation efficiency and constant group delay in the operation band.

Improvements in Wi-MAX Reception: A New Dual-Mode Wideband Circularly Polarized Dielectric Resonator Antenna

An examination of a new kind of rectangular dielectric resonator antenna (DRA) demonstrates that it delivers better gain and radiation efficiency for operating in the Worldwide Interoperability for Microwave Access (Wi-MAX) (3.3-3.7 GHz) band. The new dual-mode wideband circularly polarized (CP) DRA is implemented by using a stair-shaped microstrip feed line, a pair of L-shaped slots in the ground plane, and a rectangular DR.

A Novel Hammer-Shaped UWB Antenna with Triple Notched-Band for Rejecting RLS, WLAN and XSCS bands

A novel hammer-shaped UWB printed antenna with triple notched stop bands is presented and fabricated on FR-4 substrate with size of 40×40×1.6 mm3. The proposed antenna is composed of hammer-shaped patch with C-shaped slot, U-shaped slot on feed line, and inverted stepped notch and bevel edges with pair of L-shaped slots in partial ground plane. The fabricated antenna is tested and obtained impedance bandwidth 2.89 ̶ 11.6 GHz with three notched stop bands 3.15 ̶ 3.7 GHz, 5.45 ̶ 6.8 GHz, and 7.5 ̶ 8.8 GHz, for radiolocation system (RLS), wireless local area networks (WLAN), and X-band satellite communication system (XSCS) bands, respectively. Moreover, the antenna result shows omnidirectional radiation pattern, average gain of 3.10 dBi over the whole UWB band except at the notched frequency bands.

Compact Quad Band-Notched Monopole Antenna for UWB Systems

A novel compact microstrip-fed UWB antenna with quad notched band is proposed. The antenna consists of a rectangular radiating patch with a half circle, a tapered microstrip feed-line, and a semi-elliptical ground plane. With a pair of L-shaped slots, complementary co-directional SRR and a pair of C-shaped stubs, four notched bands are created to prevent interference from WiMAX/lower WLAN/higher WLAN/X-band. Experimental results show that the designed antenna, with compact size of 20 × 30 mm2, has an ultrawide band (VSWR < 2) from 2.68 to 13 GHz, except four notched bands of 3.13–3.8, 4.87–5.52, 5.65–6.1, 7.12–8 GHz. Good radiation patterns and stable gain within the operating band have been observed.

High gain L-T slots-loaded dual-band elliptical polarized antenna

In this letter, L-T slots-loaded dual-band elliptical polarized antenna etched on a single layer substrate is proposed. This antenna is composed from four T-shaped slots near patch boundary and two pair of L-shaped slots etched at patch corner with a rectangular slot located at the center. These combination slots are found out to produce two different frequency bands for LTE and wireless local area network application. The lower band of 2.5–2.69 GHz and the upper band of 5.725–5.85 GHz are controlled by the T-shaped slots and L-shaped slots, respectively. By symmetrically slots and properly positioning the feed position, the proposed antenna exhibits high gain of 6.91 dBi and 7.22 dBi at 2.6 GHz and 5.8 GHz, respectively, even with the compact dimensions of 44 × 44 × 1.6 mm3. Due to the orthogonal surface currents at first and third resonant modes, the proposed antenna gives an elliptical polarization with axial ratios of 7.536 dB at 2.656 GHz and 5.76 dB at 5.8 GHz. The simulation and measurement results of reflection coefficient, gain, and radiation pattern are comparable. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:184–188, 2016

Enhanced directivity and bandwidth of a stepped open‐slot antenna with L‐shaped slots and parasitic strip

In this study, a printed stepped open-slot antenna with unidirectional radiation characteristics is presented. Using a stepped feeding slot and a parasitic metal strip, the impedance matching is improved and a wide bandwidth is achieved. Additionally, by modifying the ground plane with a pair of L-shaped slots, the radiation directivity of the proposed antenna is significantly enhanced and good unidirectional radiation characteristics are obtained. To demonstrate the effectiveness of the design, a prototype antenna is fabricated and tested. Experimental results show that the antenna provides a fractional bandwidth of 101%, ranging from 3.65 to 11.1 GHz with a compact size (30 mm × 30 mm). A moderate gain, which is better than 4 dBi, is also obtained. In addition, a stable radiation directivity, which is fixed in the endfire direction (y-axis direction) is achieved. The measured front-to-back ratio is larger than 9.5 dB within the effective bandwidth.

Compact UWB microstrip antenna with satellite down-link frequency rejection in X-band communications by etching an E-shaped step-impedance resonator slot

A multiresonance and UWB monopole antenna with frequency band-notched function in 7.25–7.75 for downlink of X-band satellite communication systems is presented.Proposed antenna consist of a square radiating patch with a pair of L-shaped slots, a feed-line with an E-shaped step-impedance resonator (SIR) slot, and a ground plane with a pair of L-shaped conductor-backed plane. In this design, by cutting a pair of modified L-shaped slots with variable dimensions on the radiating patch and also by inserting a pair of L-shaped conductor-backed plane, additional resonances are excited and hence much wider impedance bandwidth can be produced especially at the higher band 125% (2.95–13.36). To achieve a band-notched function an E-shaped SIR slot was inserted in the feed-line. Simulated and experimental results obtained for this antenna show that it exhibits good radiation behavior within the UWB frequency range. The designed antenna has a small size of 12 × 18 mm2. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:922–926, 2013; View this article online at wileyonlinelibrary.com. DOI: 10.1002/mop.27456

A WIDEBAND DUAL-POLARIZED PATCH ANTENNA WITH ELECTRIC PROBE AND MAGNETIC LOOP FEEDS

A new wideband dual-polarized patch antenna consisting of a magnetically-fed and an electrically-fed is presented in the paper. The two feeds are orthogonal to each other at the center of the ground plane and generate 0 - and 90 - polarization separately. Two pairs of L-shaped slots are etched in the radiating patch to improve the impedance bandwidth. By using a shorting pin connecting the radiating patch to the ground plane, the coupling between the two feeding ports can be reduced. With the help of circuit simulation and full wave simulation, the equivalent circuit model of the antenna is established. The simulated and measured results show that the impedance bandwidths for VSWR less than 2 of the proposed dual- polarized antenna with a proflle of are 27.3% (3.29{4.33GHz) and 19% (3.05{3.69GHz) for 0 - polarization and 90 - polarization, respectively, with a height of 0.08‚0 between radiating patch and ground plane. The measured coupling between the two ports is below i20dB over the operating band. Moreover, the maximum gain of the proposed antenna is about 8.5dBi and 6.9dBi for port 1 and port 2, respectively, over the operating band. Measured results of the fabricated antenna prototypes are in good agreement with the simulated results.

COMPACT PRINTED DUAL BAND-NOTCHED U-SHAPE UWB ANTENNA

In this article, a low cost, simple, and compact printed microstrip-fed U-shape monopole ultra-wideband antenna with dual band-notched characteristics is proposed and investigated. By introducing a spiral shaped ‚/4 open stub in the microstrip feed line and a pair of L-shaped slots on the rectangular ground patch, dual band notched characteristics can be obtained respectively. The proposed antenna is successfully simulated, designed, fabricated and measured. The measured results show that the proposed antenna with dimensions of 24mm(Wsub) £ 34mm(Lsub) £ 1:6mm(H) has a large bandwidth over the frequency band from 2.75GHz to 10.6GHz with VSWR less than 2, except 3.27{4.26GHz and 5.01{5.99GHz frequency bands. The proposed antenna exhibits nearly omnidirectional radiation pattern, stable gain, and small group delay variation over the desired frequency bands.

A simple U-shaped printed ultra-wideband antenna with WLAN band rejection

In this article, a novel printed ultra-wideband (UWB) antenna with band stop characteristics is proposed. The proposed antenna is a simple U-shaped monopole structure where a rectangular strip is placed on both sides at the top of semi annular ring monopole structure. The band rejection characteristic is achieved by introducing a pair of L-shaped slots in the ground plane to prevent interference due to wireless local area network (WLAN) systems operating within ultra-wideband. To achieve the desired UWB response with WLAN band notched characteristics, the dimensions of rectangular strip, L-shaped slot, symmetrical step slot on the both edge of ground plane, a single slot in the center of the ground plane and the gap between the ground plane and the radiating structure are optimized. Frequency rejection characteristics depend on the dimension of L-shaped slot and can be fine controlled using other parameters. The antenna structure is designed, fabricated and tested. The simulation and measurement results show that the return loss = −10 dB from 3.09 to 10.6 GHz with band stop characteristics in 5.11–6.14 GHz frequency band. The radiation characteristics show its suitability for indoor wireless communication. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26091

ENHANCED BANDWIDTH DOUBLE-FED MICROSTRIP SLOT ANTENNA WITH A PAIR OF L-SHAPED SLOTS

In this paper, a modifled square slot antenna with modifled radiating patch, for UWB applications is proposed. The proposed antenna consists of a square radiating patch with a double fed structure and a ground plane with a pair of L-shaped slots which provides a wide usable fractional bandwidth of more than 140% (3{18GHz). By optimizing the L-shaped slots dimensions and rectangular slot width, the total bandwidth of the antenna is greatly improved. The designed antenna has a small size of 35 £ 35mm 2 .

Bandwidth enhancement of a planar sleeve monopole antenna for wireless communication applications

A planar sleeve monopole antenna for bandwidth enhancement is proposed and experimentally studied.By embedding a concavity sleeve in the ground plane and etching two pairs of L-shaped slots on a printed circuit board, it is found that the operating bandwidth can be significantly enhanced and the impedance bandwidth could cover the GSM, DCS, PCS, ISM/Bluetooth (2400–2480 MHz), WLAN (2400–2484 MHz), and WiMAX (2500–2690 MHz) bands. By using a capacity load on the top of the antenna, the dimension of the antenna is reduced largely. The proposed antenna has good omnidirectional radiation characteristics and achieves gains to be 2.6, 3.2, and 3.5 dBi at 900, 1800, and 2450 MHz, respectively. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2235–2238, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25445

Bandwidth Enhancement of Novel Compact Single and Dual Band-Notched Printed Monopole Antenna With a Pair of L-Shaped Slots

A dual band-notched printed ultrawideband monopole antenna is presented, with a modified ground plane. By using this modified element including a pair of variable L-shaped slots, cut in the ground plane, additional resonances are excited and hence the bandwidth is increased up to 130%. To generate single and dual band-notched characteristics, we use inverted U- and fork-shaped parasitic structures, respectively, instead of changing the patch or feedline shapes. By properly adjusting the dimensions of these capacitive-coupled elements, not only one or two controllable notch resonances are achieved, but also the lower-edge frequency of the band is decreased. The measured results show that the proposed dual band-notched monopole antenna offers a very wide bandwidth from 2.2 to 13.4 GHz (143%), defined by 10-dB return loss, with two notched bands, covering all the 5.2/5.8-GHz WLAN, 3.5/5.5-GHz WiMax and 4-GHz C bands. Impedance, radiation, efficiency and gain characteristics of the antenna are also discussed.

Broadband dual-frequency operation of circular patch antennas and arrays with a pair of L-shaped slots

By embedding properly arranged L-shaped slots in a circular patch, a novel broadband dual-frequency design is proposed and experimentally studied. With the use of an L-strip microstrip line for feeding the proposed antenna, the impedance bandwidths, determined from 10 dB return loss, of two operating bands can reach about 7.0% to 12.5% for the lower band and 18.9% to 21.5% for the higher band. Operating frequencies across the obtained lower and higher bands are of the same polarization planes, and have a tunable frequency ratio between the center frequencies of the two operating bands ranging from about 1.31-1.61. The application of the proposed antenna to the design of a 2 /spl times/ 2 broadband dual-frequency patch antenna array is also demonstrated. Details of the proposed broadband dual-frequency design are described, and experimental results of the constructed prototypes are presented and discussed.