L-shaped Slots Research Articles

Highly-miniaturized microfluidically-based frequency reconfigurable antenna diplexer employing half-mode SIRW

This article introduces a super-miniaturized frequency reconfigurable antenna diplexer based on microfluidic techniques. The proposed structure is developed using a half-mode substrate-integrated rectangular waveguide (HMSIRW). The antenna architecture consists of two HMSIRW cavities loaded with L-shaped slots, which are excited by two microstrip feedlines to realize two distinct radiating frequency bands. The footprint of the antenna diplexer is miniaturized by using the half-mode cavities. Further size reduction is achieved by the capacitive loading of the slots. The design evaluation, radiation mechanism, parametric analysis, and equivalent circuit model are discussed in detail. The empty fluidic vias are drilled on the bottom plane of the cavities and poured with various dielectric liquids to obtain independent frequency reconfigurability at two operating bands. For validation, a frequency reconfigurable antenna diplexer is designed, manufactured, and demonstrated experimentally. The measured results show that the return loss, isolation, and realized gains are greater than −20 dB, 28 dB, and 3.3 dBi, respectively, while ensuring small footprint of only 0.071λg2. The fabricated diplexer exhibits a frequency reconfiguration range greater than 17 % at both frequency bands.

A four-port self-multiplexing tunable graphene based dielectric resonator antenna with defective ground structure for high isolation and MIMO capabilities

Objectives and designA novel self-multiplexing terahertz antenna with four tunable ports is proposed in this work. The configuration comprises four rectangular dielectric resonators (DRs) affixed to a substrate, which are excited through L-shaped microstrip-fed slots positioned beneath them. To guarantee efficient isolation among the tunable antenna components, periodic unit cells are introduced into the ground plane, forming a defective ground structure (DGS). Each L-shaped slot element is equipped with a graphene strip to regulate the tunability of each DR element. Results and applicationsThis antenna can operate in various modes with resonant frequencies at 4.01, 4.23, 4.37, and 4.57 THz. It holds potential for future terahertz wireless applications that require the utilization of adjacent channels with distinct communication frequencies. Furthermore, a four-port antenna design is implemented, offering tunable MIMO capabilities with self-quadruplexing ability. The MIMO parameters, specifically the envelope correlation coefficient (ECC) and diversity gain (DG), have been assessed and found to fall within acceptable limits across the operating frequency bands. Additionally, an equivalent circuit model (ECM) is analysed to shed light on the antenna's working principle and verify the obtained results.

Monolayer actively tunable dual-frequency switch based on photosensitive silicon metamaterial

We propose a monolayer actively tunable dual-frequency switch in the terahertz (THz) range based on photosensitive silicon (PSi) metamaterial. The designed unit cell consists of hollow cross-shaped slots and four L-shaped slots made of a perfect electric conductor (PEC), with PSi embedded in both the cross-shaped and four L-shaped slots of identical dimensions. The PEC serves as the dielectric substrate. By varying the intensity of the pump beam to adjust the conductivity of the PSi, tuning of the transmittance at the resonant frequencies of the entire structure is achieved, enabling the switch to function in both ON and OFF states. Under vertical incidence of THz waves in the range of 1 THz to 3 THz, in the absence of pump beam, the PSi is in an insulating state with a conductivity of approximately 1 S/m. The proposed terahertz dual-frequency switch is in the ON state, with transmittances of 97.0% at the first resonance frequency (f1=1.736THz) and 98.3% at the second resonance frequency (f2=2.176THz), and group delays of 4.397 ps and 2.540 ps, respectively. When the pump beam intensity is 294.6 μj/cm2, the PSi is in a metallic state with a conductivity of approximately 1 × 105 S/m. The switch is in the OFF state, with zero transmittance in the range of 1 THz to 3 THz and a group delay of 0.327 ps. The calculated modulation degrees of amplitude at f1 and f2 for this terahertz dual-frequency switch are both 100%, demonstrating a high-performance switch. The two resonant frequencies f1 and f2 of the terahertz dual-frequency switch are generated by weakly coupled superposition between the embedded cross-shaped and four L-shaped PSi resonators (CSPR and FLSPR), exhibiting polarization-insensitive characteristics under vertical incidence of THz waves. We believe that this compact structure of terahertz metamaterial dual-frequency switch holds great application prospects in terahertz filtering, slow light devices, terahertz modulation, and the future 6G communication field.

DESIGN AND IMPLEMENTATION OF MULTIPLE-IN, MULTIPLE-OUT ANTENNA FOR S-BAND SATELLITE APPLICATIONS

The popularity of multiple-in, multiple-out (MIMO) technology in wireless communication systems has increased due to its ability to enhance system capacity, coverage, and reliability, leading to a rising interest in designing and implementing MIMO antennas for various frequency bands, such as the S-band. However, mutual coupling between multiple antennas can pose a significant challenge in the performance analysis of MIMO systems. In this study, we introduce a novel approach involving the utilization of an L-shaped slot in a patch element placed on an economical FR4 epoxy material with a relative permittivity of 4.4 and a loss tangent of 0.02. Multiple antennas are strategically positioned in an orthogonal arrangement to minimize coupling effects. Our proposed antenna design successfully achieves an impedance bandwidth that aligns with the -10 dB reference over a frequency range from 2.78 GHz to 2.66 GHz, making it suitable for S-band satellite applications. Furthermore, by employing a four-element MIMO antenna setup, we achieve excellent isolation characteristics, with values below -20 dB. To ensure excellent MIMO performance, we consider some diversity parameters such as envelope correlation coefficient (ECC) and diversity gain (DG), which we investigate and find to be within standard limits (ECC < 0.04, DG = 10 dB). Our study offers valuable insights into designing and optimizing MIMO antennas for S-band satellite applications and can serve as a useful reference for future research in this area.

A Compact SD-QMSIW-Based Self-Diplexing MIMO Antenna Using Two Modified L-Shaped Slots as Radiators for IoT Applications

A Compact SD-QMSIW-Based Self-Diplexing MIMO Antenna Using Two Modified L-Shaped Slots as Radiators for IoT Applications

Symmetrical L-slots Reconfigurable Triple band Antenna for Mutiband Applications

This paper introduces a novel compact reconfigurable antenna that utilizes monopole technology and tunable frequencies through switch control. The antenna is fed by a coplanar waveguide (CPW) and features a unique patch design with two L-shaped slots and integrated switches. This inventive design enables remarkable reconfigurability, allowing the antenna to operate within the frequency ranges of [3.8-3.93 GHz], [5.05-5.3 GHz], and [7-7.5 GHz]. These frequency ranges are strategically chosen to align with specific application requirements. The antenna also boasts an almost omnidirectional radiation pattern. The experimental outcomes highlight the efficacy of the proposed antenna, which occupies a compact footprint of 34x35.4 mm², making it particularly well-suited for applications requiring multiband functionality.
 Keywords: CPW-fed, multiband antenna, reconfigurable.

Eight-Element Dual-Band Multiple-Input Multiple-Output Mobile Phone Antenna for 5G and Wireless Local Area Network Applications.

This paper proposes an eight-element dual-band multiple-input multiple-output (MIMO) antenna that operates in the fifth generation (5G), n78 (3400-3600 MHz), and WLAN (5275-5850 MHz) bands to accommodate the usage scenarios of 5G mobile phones. The eight antenna elements are printed on two long frames, which significantly reduce the usage of the internal space of the mobile phone. Each antenna element is printed on both surfaces of one frame, which consists of a radiator on the internal surface and a defected ground plane on the outer surface. The radiator is a rectangular ring fed by a 50 Ω microstrip line which is printed on the top surface of the system board. A parasitic unit is printed on the outer surface of each frame, which is composed of an inverted H-shaped and four L-shaped patches. Each parasitic unit is connected to the internal surface of the frames through a via, and then it is connected to a 1.5 mm wide microstrip line on the top surface of the system board, which is connected to the ground plane on the bottom surface of the system board by a via. Four L-shaped slots, four rectangular slots, and four U-shaped slots are etched onto the system board, which provides good isolation between the antenna elements. Two merged rectangular rings are printed on the center of each frame, which improves the isolation further. The return loss is better than 6 dB, and the isolation between the units is better than 15 dB in the required working frequency bands. In addition, the use of a defected ground structure not only makes the antenna element obtain better isolation but also improves the overall working efficiency. The measurement results show that the proposed MIMO antenna structure can be an ideal solution for 5G and WLAN applications.

Compact ACS-fed MIMO antenna with dual-band notch characteristics for UWB applications

Abstract An ultra-wideband (UWB) and compact-size four-port multiple input multiple output (MIMO) antenna with a footprint of 34 mm × 34 mm fed by an asymmetric coplanar strip (ACS) is investigated. The proposed antenna is composed of four orthogonally placed identical modified elliptical-shaped radiators and achieves an impedance bandwidth of 3.4–12.2 GHz. By etching two inverted L-shaped slots in the radiator element, WLAN band and X-band are rejected in the operating communication range. Because of the usage of a meander line decoupler, the isolation enhancement at the 8–12 GHz band is achieved and the isolation is more than 18 dB for most of the UWB range. The performance of the proposed antenna is studied in terms of isolation between each port, radiation pattern, current distribution, gain, envelope correlation coefficient, diversity gain, and total active reflection coefficient. The compact size and reduced complexity make the proposed design highly suitable for portable devices.

Side-edge dual-band MIMO antenna system for 5G cellular devices

An eight-element multiple-input multiple-output (MIMO) antenna system is presented for two distinct 5G allocated bands, i.e., 3.5 and 5.2 GHz. The MIMO radiating elements are printed on each side of the mobile phone chassis, having dimensions of 150 × 7 mm2, while the microstrip feeding lines fed through a coaxial connector are printed on the main board, having dimensions of 150 × 75 mm2. The single element of the MIMO antenna system consists of a modified slotted rectangular patch radiator. One slot is composed of a hybrid shape (which consists of both T- and L-shaped patterns), and the second one is a typical inverted L-shaped slot. The placement of slots generated two different current paths, which led to dual-band response at 3.5 and 5.2 GHz. In the MIMO configuration, the arrangement of radiating elements ensures pattern diversity characteristics, which are useful for MIMO systems. Furthermore, the MIMO antenna system offers a minimum isolation of 13.5 and 21.5 dB at 3.5 and 5.2 GHz, respectively. From the results, it is also observed that the radiating elements offer a radiation efficiency of ≥70% at 3.5 GHz, while at 5.2 GHz, the radiation efficiency is noted to be >55% with acceptable gain. A comprehensive analysis of key performance parameters, e.g., envelope correlation coefficient (ECC), mean effective gain (MEG), and channel capacity (CC), was conducted, and it is noted that the proposed MIMO antenna system exhibits an ECC of less than 0.015, MEG of < −3 dB, and CC of 39.5 bps/Hz. In addition, the specific absorption rate (SAR) analysis of the proposed MIMO antenna was conducted and observed a value of 1.35 and 1.05 W/Kg at 3.5 and 5.2 GHz, respectively. To verify the computed results, a prototype of the proposed MIMO antenna was fabricated and subjected to thorough measurements. It was observed that the measured results satisfied the simulated data and aligned excellently with the measured data. Based on the performance of the proposed MIMO antenna, it became evident that the MIMO antenna structure can be used as a potential candidate for future fifth-generation (5G)-enabled smart phones.

A Three-dimensional Compact Propeller-shaped Circularly Polarized Ceiling Antenna

A three-dimensional compact propeller-shaped circularly polarized ceiling-mounted antenna loaded by inverted L-shaped slot is proposed in this paper. This three-dimensional structure has a small size, single feed and half-plane radiation mode. The antenna is composed of four alternately welded radiating elements and a disc reflector. Each radiating element is formed by etching a rectangular microstrip radiating patch and a trapezoidal microstrip radiating patch on the surface of the substrate. The four radiating elements are welded vertically on the disc reflector. The back of the disc reflector has the ground plane. The antenna is fed coaxially through the via in the center of the disc reflector. The result demonstrates that the 10-dB impedance fractional bandwidth achieves 66.3% (4.4-8.94 GHz). The 3-dB axial ratio fractional bandwidth is 2.2% (6.44-6.58 GHz). The radiation characteristic is close to half-space radiation on the xoz plane and the yoz plane. The peak gain of the antenna is 3.22 dBi. The simulation and measurement results are in good agreement. With its compact structure, effective coverage, miniaturization, etc., the antenna is very suitable for applications such as biomedical monitoring equipment and short-rangeradio communications.

Ultracompact SIRC-Based Self-Triplexing Antenna with High Isolation

An ultracompact self-triplexing antenna realized on a substrate-integrated rectangular cavity (SIRC) is discussed in this study. The proposed structure employs two L-shaped slots and an inverted U-shaped slot to radiate at three independent operating frequency bands. Three 50-ohm microstrip feed lines were used to excite the radiation in these slots. The operating frequency was individually tuned using the slot size. The slot placement and size were designed having in mind considering obtaining one or more frequency bands below the SIRC cutoff frequency, which had the advantage of enabling an ultracompact size. High port isolation was achieved by applying one of the ports orthogonally to the two remaining ones, which created a weak cross-coupling channel. A lumped-circuit model was created to examine the antenna operation. The presented design has been prototyped and experimentally validated with the measured operating frequencies of 1.92 GHz, 4.43 GHz, and 5.25 GHz for GSM, 5G, and WLAN applications, respectively. The port isolations are better than 32.4 dB according to both EM simulations and measurements. Meanwhile, the measured realized gain of the antenna is better than 4.3 dBi at all bands.

Low-Profile Wideband Circular Polarization Metasurface Antenna With Characteristic Mode Analysis and Mode Suppression

In this letter, a wideband circular polarization (CP) metasurface (MS) antenna is proposed, which is composed of a centrosymmetric structure with a mode suppressor and an asymmetric aperture-coupled feed structure separated by dielectric substrates. Based on the characteristic mode theory, the aperture-coupled feed structure consisted of an L-shaped slot and a microstrip line is employed to excite two orthogonal modes, which have a 90° phase difference to obtain CP radiation. Meanwhile, two methods have been proposed to expand CP bandwidth: one is the direct suppression of characteristic mode by decreasing the overlap frequency of operating and nonoperating mode. The other one is indirect suppression using a mode suppressor. Finally, the MS antenna with a low profile of 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> × 0.075 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> at 5 GHz is fabricated and measured. The measured results show that the proposed antenna has a 3 dB axial ratio bandwidth of 45.2% from 4.1 to 6.5 GHz and an impedance bandwidth of 41.8% from 4.1 to 6.31 GHz, and a peak gain of 7.94 dBic at 5.9 GHz.

A Reconfigurable Octa-Band Antenna with a High Gain for a Variety of Wireless Applications

The Octa-band frequency reconfigurable antenna proposed in this paper can operate in the UWB, GSM, WiMax, 5G MID BAND, WLAN (C-BAND), WLAN (S-BAND), 5G (C-BAND), and STM link-1 bands. To achieve the desired operating frequency, the ground plane of the UWB monopole antenna is modified by embedding two inverted L-shape slots. A novel frequency selective surface (FSS) reflector consisting of a 5 × 5 array of elements is located at a distance of 0.78λ at 6.2 GHz below the proposed reconfigurable antenna to improve its gain. The addition of FSS resulted in a gain improvement of 3–7 dBi. The proposed antenna has a wide switching capability, allowing it to be integrated into portable electronic devices and making it suitable for 5G and other wireless applications.

Design of MIMO Antenna with Double L-Shaped Structure for 5G NR

To satisfy the demand for 5G communication to smartphone terminal antennas in element quantity and isolation, an eight-element wideband MIMO antenna set of high isolation level is proposed. Each antenna element in the array is a double-L antenna consisting of an L-shaped slot and an L-shaped 50 Ω microstrip line. The L slot is formed by adding an I-shaped open circuit directly to the side of the rectangular slot. In addition, the antenna arrays are located on the long bezels on both sides of the mobile phone motherboard, and the coupling feed is made in the frequency range of 3.6–4.7 GHz through the L-shaped microstrip line, so as to cover the 5G NR band (N77/N78/N79). Finally, the four element pairs (8 components) achieve isolation of greater than 11 dB, the performance frequency range is 3.6–4.7GHz, the return loss is −6 dB, the total efficiency is greater than 85%, and the envelope correlation coefficient is less than 0.08. Other MIMO performances are also calculated, the design process is discussed in detail, and one-handed grip mode and two-handed grip mode are discussed to demonstrate their stabilities in real-world applications.

A compact plus shaped with L-shaped slotted microstrip patch antenna for GSM, WLAN, WiMAX, C- and X- band applications

In this research article, a compact plus-shaped L-shaped slotted microstrip patch antenna is proposed for various applications, including the Global System for Mobile communication (GSM), Wireless Local Area Network (WLAN), Worldwide Interoperability for Microwave Access (WiMAX), and C-band X-band applications. The rectangular patch includes a plus-shaped slot, with an L-shaped slot cut along it, providing enhanced bandwidth and gain with multiband resonance. The radiation pattern of the proposed antenna is also better. The proposed antenna is capable of operating in four bands: (2.0 – 2.5 GHz)/2.2 GHz for GSM and WLAN applications, (3.6 – 3.9 GHz)/3.7 GHz for Wireless Fidelity (WiFi) and WiMAX applications, (6.7 -7.4 GHz)/7.1 GHz, and (9.1 – 10.8 GHz)/10 GHz for C- and X-band applications. The impedance bandwidth is 22.7%, 8.1%, 10%, and 17% for each respective frequency range. A parametric analysis of different dimensions, Voltage Standing Wave Ratio (VSWR), surface current distribution, and radiation pattern is presented to verify and validate the design parameters in each sections.

A Zeroth-Order Slot-Loaded Cap-Shaped Patch Antenna With Omnidirectional Radiation Characteristic for UHF RFID Tag Design

The zeroth-order resonance of a compact patch structure is explored for designing a metal-mountable tag antenna in the United States (US) ultrahigh-frequency (UHF) radio frequency identification (RFID) passband. This zeroth-order resonator (ZOR) structure comprises a cap-shaped patch loaded with two L-shaped slots. Also, the patch is coupled to the ground through two inductive stubs which provide enough parasitic reactance to support the zeroth-order resonance. The proposed single-element ZOR can generate sufficient antenna impedance for achieving a conjugate match with the RFID chip impedance. Good omnidirectional radiation characteristic with vertically polarized fields can be attained in the azimuth plane when the tag antenna is placed on a metallic surface. The proposed tag antenna’s realized gain at 915 MHz is −1.382 dB [effective isotropic radiated power (EIRP) 4 W]. A stable read distance of ~15 m is obtainable with even spatial coverage in the entire azimuth plane. The resonance frequency of the proposed tag does not vary much with the object being tagged.

DESIGN AND ANALYSIS OF TRI-BAND MONOPOLE ULTRA WIDE BAND (UWB) ANTENNA

A portable, low-cost, simple monopole antenna is designed, fabricated, and tested, and measured results compared with simulations. Dual-band characteristics at 2.0-2.6 GHz and 3.1-10.6 GHz are obtained by semi-annular shaped radiation patch. Band-notched features at 2.0-3.0 GHz and 5.15-5.825 GHz obtained by providing L-shape slots, rectangular slots in ground plane, and a small ring slot on semi-annular shaped radiation patch, improve the band-notch characteristics which effect the bandwidth of resonant frequencies. The monopole ultra wide band (UWB) antenna was built on an FR4 substrate with a dielectric constant of 4.4 and a size of 50 mm &amp;times; 24 mm &amp;times; 1.6 mm. The 3D high-frequency (EM) simulation software (HFSS) is used to simulate and optimize the proposed antenna structure. The measured results of the designed antenna with different dimensions of slots have produced S11 &amp;#60; -10 dB over the three bands (2.0-2.6 GHz, 3.1-5.15 GHz, and 5.8-11.4 GHz) without a circular slot, by adjusting a circular slot radius on a semi-annular structure that improves the band-notch characteristics. The monopole UWB antenna exhibits stable gain and provides omnidirectional radiation pattern over the desired bands.

Study and design of a patch antenna for biomedical applications

This work presents the performance of a Dual-band patch antenna with L-shaped slot for biomedical applications. The antenna works at 2.4 GHz and 3.33 GHz. A semi-flexible substrate material which is “Taconic TLX (tm)” with a relative dielectric constant, ℇr of 2.55, loss tangent, tan δ of 0.0019 and thickness, h of 0.7 mm has been proposed to be the isolant element of the antenna. The size of the antenna is 60 x 55 mm². The slots in the rectangular radiating patch were introduced to produce the resonant frequencies of 2.4GHz and 3.33GHz. The simulations of the microstrip patch antenna shows the reflection coefficient, S11 of -31.67 dB and -20.25 dB at 2.4 GHz and 3.27 GHz respectively. The proposed antenna shows a peak gain of 5.01 dB at 2.4 GHz. The results were obtained using HFSS (high frequency structured simulator) software.

A Low-Profile and Compact Multi-Functional ENG-TL Inspired Antenna with Hybrid Polarizations for LTE/UMTS, WiMAX, and WLAN Applications

A novel low-profile, compact tri-band linearly and dual-sense circularly polarized (CP) antenna realized using via-less epsilon negative transmission line (ENG-TL) is investigated in this paper. The antenna miniaturization has been achieved by the zeroth-order resonance (ZOR) property of ENG-TL, which is actuated by connecting closed-loop octagonal ring radiator to an elliptical stub through a meandered-line structure. Circular polarization is accomplished by etching an L-shaped slot in the partial ground plane. The measured S11 result demonstrates that the proposed antenna features triple-band characteristics spanning from 2.42 to 2.50 GHz, 3.29 to 3.59 GHz and 5.43 to 5.55 GHz with centre frequencies of 2.46, 3.44, and 5.49 GHz, respectively. The antenna is offering linear polarization (LP) in the first and third bands while radiates left-handed CP in the + Z direction in the second band. An exceptional axial ratio (AR) of 0.062 dB has been achieved at 3.49 GHz with 3 dB axial ratio bandwidth (ARBW) extending from 3.35 to 3.67 GHz. This antenna offers an average simulated gain of 1.7 dBi across the CP band while 2.06, 1.75 and 3.67 dBi are acquired at 2.59, 3.53 and 5.62 GHz, respectively. Beside low-profile (0.013λ0 height) and miniaturized size (0.287λ0 × 0.205 λ0 ), intended antenna exhibits extended −10 dB impedance bandwidth, wide 3 dB AR bandwidth and reasonable radiation performance. It covers relevant frequency bands; therefore, it has the potential to be employed in 2.5 GHz LTE/UMTS, 3.5 GHz WiMAX, and 5.5 GHz WLAN applications.

A Parasitic Hat for Microstrip Antenna Design Based on Defected Structures for Multiband Applications

In this article, a novel design of a quad-band parasitic hat microstrip antenna is proposed for multiband applications. The proposed antenna consists of a rectangular patch of dimensions 30 mm×11 mm cut with four L-shaped slots connected with a rectangular slot in the middle of the front side of the antenna to form a parasitic hat based upon defected microstrip structure. On the other side of the antenna, a defected ground structure is integrated as five rectangular slots embedded in the ground plane with the same width but with various lengths. The suggested antenna is designed and fabricated on a substrate material with an area of 45 × 40 mm2 with a thickness of 1.52 mm to generate four frequency bands. The proposed antenna is fed by a microstrip transmission line. The simulated radiation patterns, return losses, maximum gains, and efficiencies of the antenna are carried out by using electromagnetic simulation software based on the finite element method. The measured return loss results validate that the suggested antenna can be designed to cover the frequency ranges from (3.8464 to 4.1456) GHz for sub-7GHz 5G applications, (6.7 to 7.162) GHz for ultra-wideband applications, (9.1616 to 9.5187) GHz for maritime radio-navigation positioning systems, and (11.5421 to 16.4085) GHz for radio-navigation satellite standards. The suggested antenna is based upon defected ground structure and defected microstrip structure techniques to improve the antennaperformance.