Edge Of Ground Plane Research Articles

Compact dual-band MIMO monopole dual-antenna system for 5G laptops

AbstractThe study aimed to present a dual-band 5G multi-input multi-output monopole dual-antenna system, which was configured on the upper edge of the display ground plane for laptops. The dual-antenna unit is a 29 × 2 × 3 mm3three-dimensional structure with two antennas of the same structure and size, consisting of a fed monopole antenna and a shorted monopole antenna. The antennas are arranged 4 mm apart, side by side in the same direction, to form a dual-antenna unit. Such a configuration allows the feeding points of the two antennas to be separated by the shorting point of the shorted monopole antenna, and the shorting point of the low-frequency resonant path (the shorted monopole antenna) of the two antennas to be larger than a quarter of the wavelength of the low frequency with appropriate bending. The strong current will be concentrated near the shorting point of the shorted monopole antenna when the low-frequency mode is excited, and the current flow from the ground to the feeding point of the other antenna will be reduced, achieving the isolation which is better than 10 dB in measurement between the two antennas without adopting any isolation element. The envelope correlation coefficients calculated from the measured complex E-field radiation patterns are all smaller than 0.12, which can cover the 5G dual-band operations of 3300–3600 and 4800–5000 MHz, and the measured antenna efficiencies can reach more than 40%, which are well suited for multiple antenna applications.

Compact Sub 6 GHz Slot Multiantenna System for 5G Laptops

A sub 6 GHz dual-band closed-slot multiantenna system for 5G laptops is proposed in this paper. It was installed in a clearance space, with dimensions og 217 × 3 mm2 and 1 mm away from the upper edge of the screen ground plane. The dimensions of the clearance space were the same as those of a multisystem consisting of six antennas. The dimensions of the single closed-slot antenna were 32 × 3 mm2 (0.368 λ × 0.034 λ, where λ equals the free-space wavelength of 3450 MHz. The antenna was coupled to an asymmetric T-shaped feed-in section equipped with a chip capacitor for exciting one-half and full wavelength resonance modes of the closed-slot to encompass sub 6 GHz 3300-3600 MHz and 4800-5000 MHz dual-band operations. The design of the antenna features a long and straight slot to generate the high-order mode of the closed slot in the high-frequency (4800-5000 MHz) band (not the low-frequency (3300-3600 MHz) multiplier band). Its structure is simple, and the width of its slot is only 3 mm. The antennas were arranged to be 5 mm apart in the same direction and in parallel to form a six-antenna system in order to utilize the weak electric fields located at the two closed ends of the closed-slot structure when the closed slot was excited. It showed excellent envelope correlation coefficients (ECCs) and isolation performance without the installation of isolation elements. The measured fractional bandwidth of the antenna was 10.15% and 6.73% at the center frequencies of 3450 MHz and 4900 MHz, respectively. Its measured isolation was always over 10 dB, and the efficiency was between 46% and 76%. The ECCs of the system calculated from the measured complex E-field radiation pattern were all below 0.2, which means that it is ideal for use in laptop devices with a high screen-to-body ratio and a metal back cover.

Conducting Side Sheet Loading to Enhance the Bidirectional Gain of a Wide Rectangular Slot Antenna in the 6–8.5 GHz Band

Bidirectional gain of a wide rectangular slot antenna resonating over the 6 − 8.5 GHz band is enhanced by loading a pair of conducting sheets on the ground plane edges. These sheets are vertically loaded with respect to the slot antenna for meeting two purposes – (i) to appropriately converge the oblique radiation of the slot towards the broadside direction for enhanced gain and (ii) to retain the original impedance band (reflection coefficient ≤ −10 dB) of the slot by avoiding the formation of a resonant cavity (as in the case of superstrate loaded antennas). Optimized antenna using FR-4 substrate of side 50 mm has an overall size of 2.2λ0 × 1.2λ0 × 0.5λ0, where λ0 is the free-space wavelength at the mid-band frequency of the operating band. Measurements of fabricated antenna prototype demonstrate an impedance band of 5.97–8.53 GHz with bidirectional radiation pattern, with peak in-band gain of 5.52 dBi. The average gain improvement in the band is 3.99 dB, relative to the wide-slot antenna without sheet loading. The main attraction of the proposed method is its non-resonant nature, which enables almost uniform gain enhancement throughout the original impedance band, with bidirectional radiation pattern.

Performance prediction of graphene-based patch antenna using different ground plane dimensions

This paper focuses on the development of a rectangular patch antenna with varied ground plane sizes (i.e. short edge, double ground, triple ground) using a thin film graphene-coated patch on flame retardant-4 (FR-4) glass epoxy substrate which is designed to function at 2.45 GHz. Diffraction of radiation from the ground plane's edges occurs with finite ground planes, resulting in variations in radiation pattern, radiation conductance, and resonant frequency. The ripple in the primary pattern decreases as the size of the ground plane grows larger. Even though the ground patch is built of Perfect Electric Conductor (PEC), various parametric results demonstrate that graphene patch gives a lower reflection coefficient (S11) and VSWR, as well as superior gain and directivity, when compared to copper patch. As a result, graphene-coated patches could be an excellent substitute for copper conductive patches.

Compact Configured 5G Dual-Band MIMO Loop Antenna System

This paper presents a compact configured 5G dual-band MIMO loop antenna system for laptop computers. The antenna system consists of two identical 95 × 2 mm2 four-antenna units that are arranged on the top edge of the display ground plane and are 10 mm away from the left and right sides. The four-antenna unit, each being a two-dimensional loop antenna of the same structure and size, are constructed on the on a 0.4 mm-thick FR4 substrate. The loop antenna with only 23 × 2 mm2 size is composed of a T-shaped feed-in section and a double short-circuit loop. In addition, the four loop antennas are arranged in the same direction and side by side with only 1 mm space to form a high-isolation four-antenna unit. The two sets of four-antenna units can cover 5G dual-band operation at 3300–3600 MHz and 4800–5000 MHz. The measured isolation between eight antennas is all better than 15 dB, the measured antenna efficiency is between 35% and 62%, and the measured envelop correlation coefficient ECC calculated from the electric-field radiation pattern is all less than 0.2. This compactly configured eight-antenna system is only 2 mm high in profile, making it ideal for use in 5G laptops with a high screen-to-body ratio.

Conductivity Improvement of Microdispensed Microstrip Lines and Grounded Coplanar Waveguides Using Laser Micromachining

Microdispensed transmission lines (TLs) show high conductor losses at microwave frequencies. Recently, laser micromachining has been introduced as a technique to form the slots of the coplanar waveguide (CPW). Smoother and highly conductive signal trace and ground plane edges have been obtained to enhance the CPW’s effective conductivity. Since conductor loss depends on the TL type and geometry, it is important to investigate the effect of laser micromachining on other TL types. Therefore, this letter investigates laser micromachining for microstrip line (ML) and grounded CPW (GCPW) for the first time and reports improvements in their conductivities within the 1–30-GHz frequency range. Specifically, laser micromachining is shown to decrease insertion loss at 30 GHz by 0.18 and 0.29 dB/cm for the microstrip and GCPW, respectively, when the TLs are over a 254- $\mu \text{m}$ -thick $\varepsilon _{r} = 3.6$ substrate. Effective conductivity of laser micromachined ML and GCPW is extracted as 5 and 12.5 MS/m at 30 GHz, respectively. It is shown that GCPW benefits from laser micromachining the most due to higher current concentration at the signal trace edges. Narrower lines are also shown to improve the most with the employment of laser micromachining.

End-Fire Vivaldi Antenna Array With Wide Fan-Beam for 5G Mobile Handsets

In this paper, we present a portable end-fire antenna array design for the fifth-generation (5G) mobile handsets that exploits a Vivaldi antenna and shows a wide fan-beam on the elevation plane. We make the proposed antenna array more efficient by printing on a 10-layer printed circuit board (PCB) lamination in a vertical direction of the ground plane edge. Using the proposed Vivaldi antenna array design, the radiation characteristics of 4 × 1 linear arrays are fabricated. To validate the feasibility, we perform simulations and experiments. Simulation results show that the total efficiencies of the antenna array are higher than about 8.16 - 9.46 dBi for the scanning range between 0° to 60°. Measurement results display that the antenna has S11 reply less than -10 dB in the frequency area of 27.5 to 28.5 GHz and wide beamwidth (130.8° in elevation plan, 21.35° in azimuth plan). There is a high accord between the calculated and measured results and we consider that the results in this study can be well achieved by designers who design the wide beamwidth high-speed antennas of 5G mobile terminals.

Compact Planar Antenna for Mobile Handset Applications

In this paper, we describe the procedure of simulation design and measured results of a compact planar antenna for handset applications. The broad bandwidth covering the interested frequency band for mobile handset is achieved by introduction of an open ended L-shaped slot which is newly proposed and corresponds to the monopole slot. In order to minimize the impact on circuit part placement, the proposed antenna is placed on the ground plane edge of PCB with size of 60×65 ㎟. The measurement result for 10㏈ impedance bandwidths is 640 ㎒ (1.7~2.34 ㎓), covering the required bandwidths for DCS (Digital Cellular System)-1800 (1710 ~ 1880 ㎒) / IMT (International Mobile Telecommunication)-2000 (1885 ~ 2200 ㎒) bands. In particular, we would like to emphasize the proposed antenna has an omnidirectional radiation pattern suitable for commercial wireless communication.

Integrated Frequency-Reconfigurable Slot Antenna and Connected Slot Antenna Array for 4G and 5G Mobile Handsets

A dual-function slot antenna at microwave and millimeter-wave (mm-wave) band is proposed. The design consists of a slot printed on the edge of the structure ground plane. A short-circuited varactor diode (VAR) is used to achieve the frequency tunability from 2.05 to 2.7 GHz (4G, WLAN) with a maximum realized gain of 4.5 dBi. For mm-waveband, the slot works as a connected slot antenna array (CSAA) by using eight periodic feeders with a wide bandwidth of 23–29 GHz (5G) and a maximum realized gain of 12.5 dBi. To enhance the functionality, two slots are orthogonally arranged for multiple-input multiple-output (MIMO) application. The whole structure is implemented using Rogers 5880 substrate with a board size of $70\times 60\times 0.381$ mm3. The envelope correlation coefficient (ECC) and isolation are calculated, showing satisfactory MIMO characteristics. The minimum ECC value is 0.01, while the isolation is more than 20 dB among different feeding ports. Due to the integration of 4G and 5G operations into a single narrow slot, the proposed antenna system is compact, simple, and planar in structure and, thus, attractive for future mobile handheld devices.

A Compact Circularly Polarized Antenna With Directional Pattern for Wearable Off-Body Communications

This letter presents a geometrically simple and compact circularly polarized antenna with unidirectional radiation characteristics for off-body communications. The proposed antenna is based on a microstrip-line monopole extension from a coplanar waveguide and a protruded stub from one side of the coplanar ground plane along the length of the monopole. The orthogonal components of equal amplitudes required for circular polarization are induced using the vertical stub and the horizontal edge of the coplanar ground plane. To control the radiation of the antenna towards the human body, a flexible, high-permittivity laminated substrate is used as a reflector. The topological simplicity of the antenna permits a small number of adjustable variables and therefore a reduced computational cost of the parameter tuning process. The total footprint of the proposed antenna is only $0.23\lambda _{o}\,\times\, 0.24\lambda _{o}$ = 0.05 $\boldsymbol{\lambda }_{\bf{o}}^2$ at the lowest operating frequency. The antenna is numerically and experimentally characterized in the free space and on a real human volunteer. The simulated and measured reflection coefficient indicates that the operating range of the antenna extends from 5.16 to 6.13 GHz range with 100% bandwidth overlap between the impedance bandwidth and the axial-ratio bandwidth. The peak gain of the antenna is 6.22 dBic with a stable radiation pattern in the + z -direction, high efficiency of 90%, and 0.131 W/g specific absorption rate (SAR). The antenna can be used for Unlicensed National Information Infrastructure (U-NII) worldwide band and Industrial, Scientific, and Medical (ISM) 5.8 GHz band.

A Novel Coplanar-Strip-Based Excitation Technique for Design of Broadband Circularly Polarization Antennas With Wide 3 dB Axial Ratio Beamwidth

In this communication, a novel excitation technique for the design of a single-point-fed compact low-profile wide-slot antennas with broadband circular polarization (CP) and wide 3 dB axial ratio (AR) beamwidth is presented. Two inverted L-shaped parasitic strips placed coplanar to the microstrip line of an asymmetric coplanar waveguide (CPW) and a horizontal strip that protrudes from the vertical edge of the backside ground plane of the substrate are used for CP excitation. The overall footprint of the structure is only $L_{s} \times W_{s} = 0.3\lambda _{0} \times 0.28\lambda _{0}$ when measured at the lowest operating frequency. The antenna prototype has been experimentally validated. The measured results indicate that a wide impedance bandwidth of 72% (2.26–4.85 GHz) and a CP bandwidth of 66% (2.44–4.87 GHz) can be achieved. In addition to the wideband characteristics in terms of the impedance bandwidth and CP, a stable bidirectional radiation pattern with a wide 3 dB beamwidth of 85° ± 5° is obtained for 58% of the total CP bandwidth without involving any complex circuitry. Furthermore, by placing a flat metallic reflector behind the antenna, a unidirectional radiation pattern is produced without changing the geometrical dimensions of the proposed antenna. The average realized gain of the antenna without a reflector is 3.3 dBi, whereas it increases up to 6.3 dBi with the substrate-size reflector.

Conjoined ultra‐wideband (2,300‐6,000 MHz) dual antennas for LTE HB/WiFi/5G multi‐input multi‐output operation in the fifth‐generation tablet device

AbstractConjoined dual antennas with an ultra‐wideband (UWB) of 2300‐6000 MHz for multi‐input multi‐output operation in the fifth‐generation (5G) tablet device is presented. The UWB covers not only the 5G band in 3300‐5000 MHz, but also the long term evolution high band in 2300‐2400/2500‐2690 MHz and the Wireless Fidelity band in 2400‐2500/5100‐5900 MHz. Additionally, the envelope correlation coefficient in the UWB is less than 0.1. The conjoined dual antennas have a planar printed structure and require only 32.2 mm (about 0.25‐wavelength at 2.3 GHz) along the edge of the device ground plane. The dual antennas share a conjoined section of a ring strip for bandwidth enhancement and a band‐pass resonant structure for effective decoupling. The band‐pass resonant structure is formed by a printed structure of distributed capacitor and inductor connected in series. Details of the conjoined UWB dual antennas are presented.

Performance Enhancement in Compact Inverted-L Antenna by Using 1-D EBG Ground Structures and Beam Directors

This paper describes a compact inverted-L antenna (ILA) topology that can enhance antenna performance by utilizing one-dimensional electromagnetic bandgap (1-D EBG) ground structures and two-stage beam directors. The antenna is fed through the coaxial connector and the microstrip line, and the 1-D EBG structures are embedded on the ground plane edge of the microstrip line that is closer to the planar ILA. The 1-D EBG ground structures serve as high impedance surfaces with slow-wave behavior controlling both reflection phase in plane-wave illumination and surface-wave on the horizontal-direction of the ground plane edge. The proposed antenna with 1-D EBG ground structures exhibits a wide impedance bandwidth of 810 MHz between 2.24 GHz and 3.11 GHz within a compact size of 0.21λ 0 × 0.32λ 0 . In addition, the endfire radiation performances in horizontal-polarization of the designed antenna can be enhanced without any supplementary circuits by the integration of 1-D EBG structures within compact real-estate and by placing beam directors. As the criterion for improvement of the radiation pattern, the horizontally polarized end-fire gain of 4.0 dBi and radiation intensity difference between co-polarization and cross-polarization of 14.0 dB toward the end-fire direction are experimentally ascertained.

Compact Four-Element MIMO Antenna System for 5G Laptops

This paper presents a compact dual-band four-element multiple-input multiple-output (MIMO) antenna system for the fifth-generation (5G) laptops with a large display-to-body ratio. The four antenna elements, each being a three-dimensional inverted-F antenna (IFA) of the same structure and size, are constructed on the same T-cross-sectioned substrate, the vertical part of which is embedded in the $1\times64$ mm2 clearance area created from the upper edge of the display ground plane. They are configured into two dual-antenna units. Within each unit, the two IFAs are arranged to be skew-symmetric with respect to the display ground plane, and their short-circuit points are brought close to each other to achieve the so-called short-circuit decoupling. In addition, the two units are mirror imaged of each other with a small gap in between and are connected by two decoupling chip inductors to form a high-isolation four-element MIMO antenna system. In the operating bands of 3300–3600 and 4800–5000 MHz required by 5G, the measured isolation is larger than 10 dB, and the measured antenna efficiency is beyond 35 %, both being large enough for practical applications. In particular, the proposed MIMO antenna system has a profile height of only 1.4 mm, which is very small, making it suitable for laptops with a large display-to-body ratio.

Low-profile switchable LTE/WWAN MIMO antenna system

ABSTRACTThis study proposes a low-profile switchable LTE/WWAN multi-input and multi-output (MIMO) antenna system for laptops. The main and auxiliary antennas, mirror-imaged of each other, are configured on the left and right sides of the top edge of the display ground plane. The two antennas are each a planar inverted-F antenna (PIFA) having the size of 102 × 5 × 3 mm3. The PIFA structure is matched in impedance with a set of reactive chip elements to increase the antenna operating bandwidth, and is combined with a set of switchable circuits to change the low-frequency resonant path in accordance with the switch status, ON or OFF, thus allowing the low-frequency modes to cover the LTE700 and GSM850/900 bands. Without any isolation element, an isolation of 15 dB or more can be achieved in the MIMO antenna system. The measured realized antenna efficiency is also 48% or greater.

Tomographic Characterization of a Multifunctional Composite High-Impedance Surface

The performance of a multifunctional composite high-impedance surface (HIS) has been evaluated using the coherent Doppler tomography (CDT) and finite-impulse response (FIR) filtering techniques. A combination of embroidery and advanced laser manufacturing processes were used to fabricate the conformable multifunctional glass fiber reenforced polymer HIS. The CDT method was utilized because it enabled the generation of a high-resolution tomographic map of the HIS reflectivity. Tomograms generated at high incidence angles (>80° from normal) were used to localize and FIR filter unwanted scattering associated with the ground plane edges and HIS transition regions. The resulting scattered fields from a defect (metallic block positioned in the center of the tomogram) were then used to gain a significantly distinctive insight into the HIS scattering properties. Furthermore, unlike traditional methods for characterizing HISs, the CDT and FIR methods presented herein are applicable to electrically large and conformal HISs.

Hepta-Band Coupled-Fed Loop Antenna For LTE/WWAN Unbroken Metal-Rimmed Smartphone Applications

A hepta-band coupled-fed loop antenna for LTE/WWAN unbroken metal-rimmed smartphone applications is proposed. The unbroken metal rim is designed as a part of the loop antenna radiation structure, which is also composed of a system ground, a coupled-fed U-shaped microstrip line, and an L-shaped microstrip line. The feeding and L-shaped microstrip lines are located on an ungrounded area of 72 × 8 mm2 along the top short edge of the system ground plane on an FR4 substrate. The operating band of the antenna is widened by the matching circuit elements on the feeding line. Combining multiple resonant modes generated by the coupling loop, the proposed antenna can operate on two wide operating bands of 824–960 and 1710–2690 MHz. The detailed working principles of the proposed antenna are described. Good antenna radiation characteristics are obtained. Both experimental and simulation results are presented and discussed.

Dual‐feed U‐slot antenna having low envelope correlation coefficients for the LTE MIMO operation in the metal‐framed smartphone

AbstractA printed dual‐feed U‐shaped open‐slot (U‐slot) antenna disposed close to the top or bottom short edge of the system ground plane in the metal‐framed smartphone for the LTE (long‐term evolution) MIMO (multi‐input multi‐output) operation is presented. The U‐slot is printed in the ground region within 10 mm to the short edge of the system ground plane and its two open ends are disposed at the short edge thereof. The former makes the system ground plane capable of accommodating a large display panel for the smartphone, while the latter decreases the effects of the user's hand holding the smartphone. The U‐slot is short‐circuited at one position therein to provide one longer open slot and one shorter open slot, which are fed separately by two feed networks to form Ant1 and Ant2. Ant1 can cover the LTE low band (LB, 746–960 MHz for Band 13/5/8) and LTE middle/high band (M/HB, 1710–2690 MHz). Ant2 can cover the LTE M/HB in 1710–2690 MHz. In addition, very low envelope correlation coefficients (ECCs) less than 0.1 in the LTE M/HB for Ant1 and Ant2 can be obtained. That is, in addition to the coverage of the LTE LB, the dual‐feed U‐slot antenna can be applied for the 2 × 2 LTE M/HB MIMO operation. The antenna structure and operating principle of the dual‐feed U‐slot antenna are presented, and the antenna performance is verified by the experimental study.

User Impact on Phased and Switch Diversity Arrays in 5G Mobile Terminals

In this paper, a mobile terminal phased array at 28 GHz with different scan angles is compared with a switch diversity antenna array at 28 GHz in the case of antenna beams pointing at the user’s body. In the switch diversity antenna array, there is only one element out of eight operating each time. The paper is carried out in data mode with a standing user, which includes both body blockage and user hand effects. The metrics of coverage efficiency, antenna shadowing power ratio, and isotropic antenna shadowing power ratio are utilized in the investigation. It is found that the scan angle of a phased array higher than 90° is not necessary for this scenario, because the user body will contribute to the total radiation at large angles by scattering the radiated energy around the body. For the linear phased antenna arrays on the edge of the mobile device ground plane, it can be concluded that in order to achieve the highest coverage efficiency and lowest user shadowing it is more beneficial to use a phased array instead of a switch diversity array. However, if the losses of the phase shifters and the feeding network from the phased array are higher than 5 dB, the switch array can be used, which will also decrease the complexity of a system.

Validation of Prediction Method of Common-Mode Current Reduction Based on Imbalance Difference Model for Differential Transmission Line Placed Near Edge of Adjacent Ground Plane

Validation of Prediction Method of Common-Mode Current Reduction Based on Imbalance Difference Model for Differential Transmission Line Placed Near Edge of Adjacent Ground Plane