Slot In Ground Plane Research Articles

A Compact C-Band Multiple-Input Multiple-Output Circular Microstrip Patch Antenna Array with Octagonal Slotted Ground Plane and Neutralization Line for Improved Port Isolation in 5G Handheld Devices

In this paper, an eight-port antenna array is presented for 5G handheld terminals to support multiple-input multiple-output (MIMO) operations. The reported design involves three layers: the top contains eight circular microstrip feed elements; the middle is a low-cost FR-4 substrate, and the bottom layer is a ground plane with four etched octagonal slots. Each resonating element is fed by 50-ohm sub-miniature connectors. To mitigate the detrimental effects of mutual coupling of ports and enhance overall isolation between the adjacent microstrip-fed circular patch elements, a neutralization line is strategically implemented between the feed lines of the antenna array. The design configuration involves two elements at each vertex of the printed circuit board (PCB). The overall dimensions of the PCB are 150 × 75 mm2. Each slot and its corresponding radiating elements exhibit linear dual polarization and diverse radiation patterns. The proposed antenna design achieves the required operating bandwidth of more than 1000 MHz spanning from 3 to 4.2 GHz, effectively covering all the upper C-band frequency range of 3.3 GHz to 4.2 GHz allocated for 5G n77 and n78 frequency range 1 (FR1). Required port isolation and lower envelop correlation coefficient (ECC) are achieved for the band of interest. The proposed design gives a peak gain of up to 4 dB for the said band. In addition to these results, degradation in the performance of the antenna array is also investigated during different operating modes of the handheld device. Measured results from the fabricated unit cell and whole array also have a good match with simulated results. On the whole, the proposed antenna possesses the potential to be used in 5G and the open radio access network (ORAN) compliant handheld devices.

Multi-polarized Reconfigurable Antenna with Ground Plane Slot and Capacitance Feeding for UAV-to-everything Communications

Multi-polarized Reconfigurable Antenna with Ground Plane Slot and Capacitance Feeding for UAV-to-everything Communications

Low-coupling reflective metasurfaces for accurate near-field focusing

Metasurface is a 2D metamaterial which manipulates electromagnetic wavefront by carefully designing the transmissive or reflective responses of the planar subwavelength structures. Despite various emerging new functionalities, one of the limitations of metasurfaces in practical applications is the lack of control accuracy of its local amplitude and phase responses. This is in part caused by the discrepancy between the periodic EM simulated responses of unit cells and the actual non-periodic metasurfaces when functionality-determined amplitude and phase gradients are introduced. Under such conditions, the focusing capabilities of metasurfaces can be greatly affected. In this paper, we address this problem by introducing a slotted ground plane metasurface design which reduces the above-mentioned discrepancy by limiting the mutual coupling effects of a unit cell with its surrounding elements. An offset-fed near-field focusing reflective metasurface is designed and fabricated to verify the performance of the proposed design. Both the EM simulated and measurement results demonstrate the advantages of the proposed design in terms of sidelobe level and transfer efficiency.

Compact designs of circular microstrip antennas employing modified ground plane for wideband response

Wideband Compact designs of circular microstrip antennas by employing modified ground plane profile are proposed. Ground plane slots reduces patch fundamental mode frequency and Bow-tie shape of the same yields wider bandwidth on thinner substrate, thus achieving wider bandwidth with a smaller antenna volume. Optimum results are achieved using three rectangular slots cut Bow-tie shape ground plane. Against the conventional ground plane design, modified ground plane antenna yields 25% bandwidth increment, 0.03λg reduction in substrate thickness, 35.12% reduction in the resonance frequency, 66% reduction in the patch area with a broadside peak gain of 5.5 dBi. Reported wideband configurations do not provide bandwidth enhancement with a patch size reduction, and thus this is the novelty in the proposed work. Simulated results are have been experimentally verified that shows close agreement.

Edge Hole Effect on Isolation of UWB MIMO RDRA for 5G Outdoor Applications

For 5G sub-6 GHz outdoor applications, a highly isolated two-port rectangular dielectric resonator antenna (RDRA) with UWB MIMO is presented in this research. For isolation enhancement purposes at the lower frequency band (2.27 GHz-2.62 GHz), a longitudinal slot is inserted at the ground plane. For isolation enhancement at the higher frequency band (3.9 GHz-5.73 GHz), an edged hole is inserted in the RDRA. Investigations are conducted on the impacts of slotted ground as well as edged hole radius on isolation. The orthogonal feeding scheme of UWB MIMO RDRA considering both edged hole and slotted ground plane effects are investigated. For the edged hole MIMO RDRA with a slotted ground plane, isolation is better than -24.7 dB at a higher frequency band and is better than -15.5 dB at a lower frequency band. This isolation improvement is explained by the surface current density distribution. The use of an edged hole RDRA and an aperture-coupled orthogonal feeding allows UWB bandwidth and good efficiency performances on the 5G operating bands. To justify the MIMO performance, the envelope correlation coefficient (ECC) and diversity gain (DG) are applied.

A penta‐band microstrip slot antenna for S‐, C‐ and X‐band applications

AbstractThis letter presents a compact penta‐band microstrip slot antenna. The proposed antenna comprises a microstrip feed line on the top plane, a polytetrafluoroethylene (PTFE) substrate, and a slotted ground plane. Different shapes of slots and two pairs of horizontal strips on the ground are introduced to achieve five frequency bands. A prototype is fabricated and measured to demonstrate the validity of the design. According to the measured result, the fabricated antenna can operate at five operating frequencies with an impedance bandwidth of 2.41–2.55 GHz (5.65%) for Bluetooth and WLAN, 3.31–3.58 GHz (8.14%) for WiMAX and Sub‐6 GHz 5G applications, 4.52–4.76 GHz (5.17%) for radiometry, 5.10–6.20 GHz (19.47%) for WLAN and ITS, and 10.14–12.40 GHz (20.10%) for radar applications. Moreover, the proposed antenna shows a bi‐directional radiation pattern at each operating band.

BANDWIDTH AND GAIN ENHANCEMENT OF CUP SHAPED UWB MICROSTRIP PATCH ANTENNA WITH DEFECTIVE GROUND PLANE FOR SUB-6 GHZ 5G APPLICATIONS

This paper presents the design of slotted ground plane and a circular ring slotted microstrip patch antenna for new radio (NR) band, sub-6 GHz, WLAN and Licensed Assisted Access (LAA) 5G applications. The design consists of cup -shaped microstrip patch antenna with a defective ground structure (DGS). The circular ring slot at the top of the patch and the modified rectangular slots at the bottom are helpful to improve the performance of the antenna, thereby increase the efficiency, bandwidth, gain and improved s-parameters. The proposed antenna is designed on FR4-epoxy substrate and inset feeding technique. The design and simulation of my proposed work are done using HFSS (ANSYS-Electronics suite 19.2×64 version). The antenna has a bandwidth of 2.56 GHz with maximum gain of 2.27 dB. The antenna operates for the bandwidth from 4.04GHz to 6.6 GHz which covers NR-New Radio band (3.4-4.2 GHz), Sub 6 GHz 5G band (n-79) (4.44-5.0 GHz), WLAN (5.15 - 5.35 GHz) and Licensed Assisted Access (LAA) band.

Defected ground structure-based wideband circularly polarized 4-port MIMO antenna for future Wi-Fi 6E applications

A circularly-polarized (CP) wideband 4-port Multi-input multi-output (MIMO) antenna is proposed. The novel contribution of the proposed work lies in achieving CP through an L-shaped feedline and a carefully engineered orthogonally placed slotted ground plane geometry leading to a defected ground structure (DGS). A single-fed CP antenna structure is then converted to the 4-port MIMO antenna that achieves higher isolation due to polarization diversity. The MIMO antenna demonstrated an impedance bandwidth (IBW) spanning 65.01 % (from 3.81 GHz to 7.48 GHz), along with an axial ratio bandwidth (ARBW) of 20.10 % (from 5.47 GHz to 6.70 GHz). The 4-port CP MIMO antenna shows decent MIMO diversity performance. The measured results of the fabricated structure displayed good agreement with the simulated results. Antenna having both MIMO capability and circular polarization helps in reducing the multipath fading effect while increasing the latency. Thus, the proposed antenna having a wide overlapping Axial Ratio (AR) and Impedance Bandwidth (IBW) can be a very good choice for future devices using the Wireless Fidelity (Wi-Fi) 6E band.

Circular Polarized Antenna with Rotationally Positioned Microstrip Structures For UHF RFID Applications

With the use of wireless communication and the industry 4.0 revolution, RFID technology integration in production has increased. The large-scale preference of RFID systems is both cost-effective and significantly increasing production. It is an innovation that provides convenience for large production facilities such as product control, in-plant tracking, storage, inventory operations. In this paper, a compact circularly polarized (CP) reader antenna is presented for ultra-high frequency (UHF) radio frequency identification (RFID) applications. The proposed antenna consists of a circularly slotted ground plane and folded plus-shaped structures with vertical and horizontal positions. Microstrip line feeding technique is used in the vertically folded plus-shaped structure positioned on the front surface. The antenna has a 10 dB return loss bandwidth of 80 MHz (840-920) and a 3 dB axial ratio bandwidth of 20 MHz (855-875). Theproposed antenna has dimensions of 75 × 75 × 1.6 mm3 . The size advantage of the single-layer and singlefed structure enables its applicability in portable systems.

Characteristic-Mode-Analysis-Based Compact Vase-Shaped Two-Element UWB MIMO Antenna Using a Unique DGS for Wireless Communication

The modern electronic device antenna poses challenges regarding broader bandwidth and isolation due to its multiple features and seamless user experience. A compact vase-shaped two-port ultrawideband (UWB) antenna is presented in this work. A circular monopole antenna is modified by embedding the multiple curved segments onto the radiator and rectangular slotted ground plane to develop impedance matching in the broader bandwidth from 4 to 12.1 GHz. The UWB monopole antenna is recreated horizontally with a separation of less than a quarter wavelength of 0.13 λ (λ computed at 4 GHz) to create a UWB multiple input and multiple output (MIMO) antenna with a geometry of 20 × 29 × 1.6 mm3. The isolation in the UWB MIMO antenna is enhanced by inserting an inverted pendulum-shaped parasitic element on the ground plane. This modified ground plane acts as a decoupling structure and provides isolation below 21 dB across the 5–13.5 GHz operating frequency. The proposed UWB MIMO antenna’s significant modes and their contribution to antenna radiation are analyzed by characteristic mode analysis. Further, the proposed antenna is investigated for MIMO diversity features, and its values are found to be ECC < 0.002, DG ≈ 10 dB, TARC < −10 dB, CCL < 0.3 bps/Hz, and MEG < −3 dB. The proposed antenna’s time domain characteristics in different antenna orientations show a group delay of less than 1 ns and a fidelity factor larger than 0.9.

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 × 24 mm × 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 < -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.

A Comprehensive Analysis, Design, and Experimental Evaluation of Single-Loop Polygonal Slotted RF Resonators and WPT Systems

A thorough analysis of slotted ground plane (SGP)-based resonators designed for wireless power transfer (WPT) applications is reported in this paper. For the first time, some new findings that relate a resonator and WPT performance metrics to the slot shape, quality factor (Q), and radiation loss are presented in a very comprehensive manner. As a case study, a single-loop polygonal shape was considered to carry out all analyses and investigations. It has been identified that the slot shape has no impact on the performance of resonators and, hence, developed WPT. Instead, the performance is hugely dependent on Q of resonators regulated by the chosen slot area. These findings allow the conceptualization of systematic analysis of WPT systems and the development of design schemes that are readily realizable, and they also enable significant improvement in power transfer efficiency (PTE). The developed prototypes conforming to the industrial, scientific, and medical frequency bands show an enhancement in PTE to the extent of 11% during the measurements. The proposed analysis and design approach are very important steps in advancing state-of-the-art radio-frequency WPTs. In essence, this has the potential to reinvigorate the stagnated SGP-based WPT systems so as to facilitate the requirements of low-power applications.

Frequency selective reconfigurable microstrip antenna for cognitive radio applications

For the efficient utilization of electromagnetic radio spectrum cognitive radio communication system is employed, which deals with the spectrum scarcity. An efficient antenna is essential for the appropriate selection of the available frequencies. This paper presents the design and implementation of frequency reconfigurable antenna for cognitive radio applications. Reconfigurable inverted U-shape microstrip patch antenna feeding by 50 W microstrip line is designed and implemented. The designed and implemented antenna applied for switching frequency between 3.25 GHz to 4.1 GHz by choosing a specific sub-band from the specified wideband. The frequency reconfiguration was achieved by using twelve PIN diode switches by placing them on the slotted ground plane of the antenna. The PIN diodes were organized in such a way as to alter antenna bandwidth and to shift the operating band. The switching of PIN diodes controlled using the microcontroller to select the appropriate frequency. The performance of the simulated and fabricated antenna is investigated using different parameters.

Design and analysis of broadband circularly polarized compact planar antennas for 2.45 GHz RFID handheld reader applications

AbstractIn this article, an innovative design of a broadband circularly polarized compact planar antenna for RFID (radio frequency identification) receivers is presented. The suggested structure used the concept of slots loaded parasitic element printed underneath a coplanar waveguide-fed radiator to achieve the circularly polarized (CP) radiation and size reduction. A parasitic element loaded with F-slot and L-slot, and a window-type slotted ground plane was used to achieve resonance at 2.45 GHz with right-handed circularly polarized radiation for RFID handheld reader application. Experimental results confirmed that the designed antenna of size 16.5 × 14.8 × 1.6 mm3 attained a −10 dB impedance bandwidth of 15.8% (from 2.330 to 2.716 GHz) and 3 dB AR bandwidth of 3.43% (from 2.410 to 2.494 GHz). An axial ratio of 0.43 dB was achieved in the boresight of the antenna at the 2.45 GHz RFID band. The concept of electric field distribution on the antenna was used to elaborate the excitation of CP radiation in the antenna.

An Antipodal Antenna with Improved Axial Ratio Bandwidth

A circularly polarized (CP) slot antenna is implemented utilizing a Y-shaped radiating strip connected to a quarter wave microstrip feed line for better impedance matching. A parasitic strip, and an antipodal Y-shaped strip are used here to obtain wide axial ratio bandwidth. Utilizing of two optimized spring notches and a rectangular slit on the trapered slot ground plane enhanced circularly polarized radiation. The compact antenna (28 × 28 mm2; 0.277λ0 × 0.277λ0, λ0 is free space wavelength at 2.965 GHz) gives wide measured impedance bandwidth (IBW) from 2.965 to 13.461 GHz, center resonating frequency (fr ) 8.213 GHz, IBW 127.8% and a total of 10.496 GHz and measured wide CP band of 2.473 GHz (4.209–6.682 GHz, center CP resonating frequency (f cp) 5.445 GHz, 45.41%). The maximum measured peak gain of this antenna is 4.672 dBi at 6.5 GHz. Implemented antenna is suitable for some part of “S”, “C” and “X” band wireless communication applications.

Analysis of Tripleband Single Layer Proximity Fed 2x2 Microstrip Patch Array Antenna

Microstrip patch antennas that are multiband and downsized are required to suit the high demand of modern wireless applications. To meet this need, a one-of-a-kind triple band array antenna has been proposed. The proposed 2x2 microstrip patch array, which comprises of four hexagon-shaped radiating patches are electromagnetically excited by a centrally positioned microstrip feed line in the same plane along with a slotted ground plane, is investigated. CST Microwave Studio, a powerful 3D electromagnetic analysis programme, was used to design and optimize the array antennas. The 2x2 array antenna was constructed on a FR-4 substrate with a dielectric constant of 4.3, a loss tangent of 0.001, and a height of 1.6mm. To optimize energy coupling from the feed line to the radiating patches, the ground plane has an H-shaped groove cut into it. The suggested 2x2 array antenna's multi- frequency behaviour is shown. Three resonant peaks were detected at 1.891GHz, 2.755GHz, and 3.052GHz. The observed bandwidths for these resonances are 234MHz, 69MHz, and 75MHz, respectively, with measured gains of 7.57dBi, 6.73dBi, and 5.76dBi. The goal of this work is to design, build, and test a single layer proximity fed array antenna. Standard proximity fed array antennas contain two substrate layers; however this array antenna has only one. As a consequence, the impedance matching and alignment are better. Simulated and experimental results showed that the this 2x2 array antenna operates in various important commercial bands, such as L and S bands and the array antenna might be beneficial for a wide range of wireless applications. The proposed antenna has good Impedance, S11, and radiation qualities at resonant frequencies. In this work, the 2x2 array antenna with hexagon-shaped radiating patches was successfully created utilizing the single layer proximity fed antenna concept and gap coupled parasitic patches.

Wireless power transfer system for deep-implanted biomedical devices

In this paper, a dual-band implantable rectenna is proposed for recharging and operating biomedical implantable devices at 0.915 and 2.45 GHz. The rectenna system consists of a compact dual-band antenna based on a meandered-resonator as well as efficient dual-band rectifier circuit. Both components (antenna and rectifier) are integrated inside a capsule device to simulate and experimentally validate the rectenna. The antenna occupies lower volume (5 times 5.25 times 0.25 hbox {mm}^{3}), where compactness is achieved using meandered geometry and a slotted ground plane. It maintains quasi-omnidirectional radiation patterns and peak realized gains of −22.1 dBi (915 MHz) and −19.6 dBi (2.45 GHz); thus, its capability is enhanced to harvest the ambient energy from multiple directions. Moreover, a dual-band rectifier is designed using a dual-branch matching network (an L-matching network and open-circuited stub in each branch) with a radio frequency (RF) to direct current (DC) conversion efficiency of 79.9% for the input power of 1 dBm (lower band: 0.915 GHz) and 72.8% for the input power of 3 dBm (upper band: 2.45 GHz). To validate the concept of the rectenna, the implantable antenna and rectifier are fabricated and attached together inside a capsule device, with the measured results verifying the simulated responses. The proposed rectenna efficiently rectifies two RF signals and effectively superimposes on a single load, thus, providing a distinct advantage compared to single-band rectennas. To the best of the authors’ knowledge, this is the first-ever implantable rectenna to perform dual-band RF signal rectification.

A Compact MIMO Antenna for 5G NR Frequency Bands n257/n258/n261 Under Millimeter-Wave Communication

In this article, a compact, planar, 4-port ultra-wideband (UWB) multiple-input–multiple-output (MIMO) antenna is conceived for fifth-generation millimeter-wave applications. The suggested MIMO antenna architecture consists of four identical hexagonal-shaped slotted ground plane and four microstrip line feeds. The MIMO antenna's four components are arranged orthogonally to one another to provide a high level of inter-element isolation. The antenna prototype is constructed on a (12.5×12.5×0.8 mm3) Duroid 5880 substrate having a relative dielectric constant (ϵrsub) of 2.2 and loss tangent (tanδ) of 0.0009. Diversity characteristics such as envelope correlation coefficient (ECC), and diversity gain are determined to validate the proposed MIMO antenna's work qualities. The isolation is more than 18 dB, indicating that the proposed design is suitable for use as a quad-port MIMO antenna. The proposed MIMO antenna has a 30.47% impedance bandwidth throughout the frequency range of 26.7 GHz to 36.3 GHz, making it suitable for 5G New Radiofrequency bands n257/n258/n261 under Millimeter-Wave Communication. Positive correlations between the simulated and experimental findings are observed.

Compact dual‐band quasi‐Yagi antenna with pattern diversification for WI‐FI 6E applications

AbstractA dual‐band quasi‐Yagi antenna with diverse radiation patterns at different frequency bands is presented for the Wi‐Fi 6E applications. It has multiple working bands that cover the two existing bands of traditional Wi‐Fi 6, that is, from 2.4–2.4835 to 5.17−5.835 GHz, as well as the upcoming extended Wi‐Fi 6E band that covers the 5.925−7.125 GHz band. The proposed antenna consists of a microstrip (MS) line, a coplanar strip‐line (CPS), a bow‐tie driven dipole element, a slotted ground plane and a parasitic director element. By jointly employing these structures, multiple resonances can be generated, where the resonance with largest current path results in low‐frequency working band, while the others are merged to form a relatively wide high‐frequency band. In the low‐frequency band, the antenna has an omnidirectional radiation pattern with wide beam‐coverage, while in the high‐frequency band, the antenna can achieve directional radiation pattern with high gain value. An antenna prototype is then fabricated and measured for validation. Good agreement between the simulated and measured results is observed. The measured −10 dB impedance fractional bandwidth are 4.3% (2.38−2.484 GHz) and 60.6% (4.47−8.36 GHz) in the low‐ and high‐frequency bands, respectively, associated with peak gain values 0.64 and 6.22 dBi. The antenna's overall size is 0.22 λL × 0.20 λL × 0.006 λL. The proposed antenna is a good candidate for multiple kinds of Wi‐Fi applications.

A low‐profile ultrawideband circularly polarized slot antenna array based on artificial magnetic conductor array reflector

A broadband circularly polarized (CP) slot antenna unit that is composed of a sector-shaped radiator and an irregular pentagon slot ground plane is initially investigated. The CP characteristics are realized based on unbalanced feeding and loading of irregular slot structure. To increase the gain and yield ultrawideband operation, a 2 × 2 antenna array with a sequential rotational feeding method is introduced. To further reduce the total profile of the proposed antenna array to 0.15λ0, an artificial magnetic conductor array reflector is loaded between the antenna array and the feeding network. The measured 10-dB impedance bandwidth of the proposed antenna array was 82.6% (8.31–20.0 GHz), and its corresponding CP bandwidth was 65.4% (8.61–16.98 GHz), and the radiation efficiency of the antenna is also higher than 80%. Besides exhibiting very good axial beams across the wide CP bandwidth, a peak gain of up to 11.1 dBic is also achieved. Thus, it is suitable for X-band and Ku-band satellite communication applications.