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A Compact MIMO Antenna Design Using the Wideband Ground-Radiation Technique for 5G Terminals
이예,QULONGYUE,김형동 한국전자파학회 2024 Journal of Electromagnetic Engineering and Science Vol.24 No.1
This paper introduces a 4 × 4 multiple-input and multiple-output (MIMO) antenna application based on the conception of the characteristic mode of 5G terminals. The proposed antenna used a series capacitor and a parallel capacitor to control input impedance matching, while the resonance frequency was controlled by employing a resonance loop capacitor. In this way, we achieved a compact miniaturization antenna that uses ground radiation for the target 5G New Radio (NR) operating bands with n48, n77, and n78 bands. The simulation and measurement data revealed that the –6 dB bandwidth of the proposed antenna was approximately 1,240 MHz (ranging from 3.14 GHz to 4.38 GHz), while the efficiency also improved from 38.7% (reference) to 49.1% (proposed) within the 3 GHz to 4.6 GHz range. Furthermore, the radiation pattern exhibited satisfactory radiation performance. Therefore, it was concluded that the proposed 4 × 4 MIMO antenna set technology has promising prospects for application in 5G communication terminals in the future.
MIMO antennas using controlled orthogonal characteristic modes by metal rims
Qu, Longyue,Lee, Hongkoo,Shin, Hyunwoong,Kim, Min-Gi,Kim, Hyeongdong IET 2017 IET microwaves, antennas & propagation Vol.11 No.7
<P>A metal-rimmed multiple-input multiple-output (MIMO) antenna design operating below the 1 GHz frequency band is proposed that offers a wide bandwidth, high isolation, low correlation, and compact size. The proposed technique is based on metal-rimmed mobile phones with four gaps, and the overall design occupies a small size in the ground plane. Orthogonal ground mode resonances are controlled to be equal to the operating frequencies, providing high antenna performance and good diversity performance. The proposed main antenna is achieved by utilizing the upper-side rim to tune the ground mode resonance along the length of the ground plane to be equal to the operating frequency; moreover, a coupling slot couples strongly with the ground mode resonance to achieve a -6 dB bandwidth from 0.695 to 1 GHz (305 MHz). The orthogonal ground mode along the width of the ground plane is used for diversity antenna design. Similarly, the ground mode resonance is made equal to the operating frequency by controlling the left-side metal rim such that a simulated -6 dB bandwidth from 0.850 to 0.920 GHz (70 MHz) is achieved. The simulated isolation is more than 11.5 dB in the operating band, and the measured envelope correlation coefficients is below 0.1.</P>
Qu, Longyue,Zhang, Rui,Shin, Hyunwoong,Kim, Jihoon,Kim, Hyeongdong Institute of Electrical and Electronics Engineers 2017 IEEE transactions on antennas and propagation Vol.65 No.2
<P>In this communication, we introduce a mode-controlled ground radiation antenna comprised of a resonance-controlled ground plane and a nonradiating feeding slot for wideband applications in mobile devices. A 110 mm <TEX>$\times50$</TEX> mm ground plane for 850-MHz operation is studied as a test case. The resonant frequency of the ground plane is lowered by adding metal loads at the top and bottom intended for strong coupling with a miniature feeding slot located at one end, so that the ground plane is resonant as a half wavelength dipole-type radiator. The metal loads can be the structures of strips, plates, or wires, and they can take the form of broken metal rims or frames with cuts or gaps in smartphones. In addition, the metal loads are connected to the ends of the ground plane by lumped elements (inductors and/or capacitors) for easy control of the resonance mode and compact design. Equivalent circuit model and corresponding equations are provided for theoretical analysis. The impedance bandwidth based on 3:1 VSWR is 210 MHz (from 760 to 970 MHz), with an average efficiency of 77%. Geometrical characteristics of the metal loads are shown to be important parameters for the antenna performance.</P>
Qu, Longyue,Zhang, Rui,Kim, Hyeongdong IET 2016 IET microwaves, antennas & propagation Vol.10 No.5
<P>A compact and easy to fabricate decoupling method is proposed to yield high isolation for the multiple-input and multiple-output (MIMO) ground radiation antenna (GradiAnt) system. The proposed MIMO antenna system is comprised of two symmetrical, closely spaced, loop-type (GradiAnts) with a ground-coupled loop-type isolator inserted between them. The isolator can be seen as a series resonant circuit which is connected with lumped components to control decoupling. In the proposed MIMO GradiAnt system, a coupling null is induced due to the ground-coupled isolator, which effectively can be used for isolation enhancement between two GradiAnts. Within WLAN band, a minimum 14 dB isolation with a peak value of 42 dB at 2.42 GHz is achieved. In this manuscript, the decoupling principle and controlling mechanisms are first explained, then the antenna performances and tuning mechanisms are discussed in detail. The simulation and the measurement of the MIMO antenna, including the scattering parameters, efficiency, radiation patterns, peak gains and envelope correlation coefficients are conducted to verify the performance of the proposed MIMO system.</P>
Qu, Longyue,Kim, Hyeongdong Institute of Electrical and Electronics Engineers 2018 IEEE transactions on antennas and propagation Vol.66 No.10
<P>This paper investigates the design of a novel single-feed dual-element antenna that can be used to achieve circular polarization (CP) performance for mobile devices at arbitrary locations. The severe conditions needed to achieve CP remain as difficult issues for small mobile antennas; this is the case because the ground plane, rather than the antenna structure, contributes to the dominant radiation as the antenna volume shrinks. A novel concept of decomposing the antenna into two elements, which are independently coupled to two orthogonal ground modes for far-field radiation, is proposed through a theoretical analysis based on characteristic mode theory. The proposed dual-element antenna is comprised a loop-type element and monopole-type element, where one element is directly fed and the other resonates parasitically. In this way, the magnitudes and phase difference between two radiated field components can be controlled through antenna tuning without needing to manipulate the ground plane. Both simulations and measurements are conducted to verify the proposed antenna design with a widely used smartphone.</P>
High-Sensitivity Ground Radiation Antenna System Using an Adjacent Slot for Bluetooth Headsets
Qu, Longyue,Zhang, Rui,Kim, Hyeongdong Institute of Electrical and Electronics Engineers 2015 IEEE Transactions on Antennas and Propagation Vol. No.
<P>In this communication, we introduce a high-sensitivity antenna system for Bluetooth headsets dealing with the numerous and unidentified noises in a printed circuit board (PCB). This antenna system is composed of a ground radiation antenna for Bluetooth applications and an adjacent slot for noise suppression. A loop-type circuit is used to model a noise source on the PCB to provide wide-frequency spectrum noise currents to analyze the noise performance of the high-sensitivity antenna system. Decoupling between the noise sources and the antenna port can lead to high sensitivity. An adjacent slot is designed as part of the system to improve the sensitivity, based on the decoupling theorem. This proposed system is effective and applicable for high-sensitivity antenna design, as verified through simulation and active measurements of Bluetooth headsets.</P>
Circular Polarized Ground Radiation Antenna for Mobile Applications
Qu, Longyue,Zahid, Zeeshan,Kim, Hyung-Hoon,Kim, Hyeongdong Institute of Electrical and Electronics Engineers 2018 IEEE transactions on antennas and propagation Vol.66 No.5
<P>Here, we propose a ground radiation antenna (GradiAnt) with circular polarization (CP) by applying the ground-mode tuning (GMT) technique to the ground plane. We demonstrate that a GradiAnt at an arbitrary location of the ground plane can simultaneously excite two orthogonal modes of the same magnitude, and the phase difference between the two modes can be adjusted via GMT to achieve CP in mobile antennas. The proposed GradiAnt can be viewed as a combination of an electric coupler (J-type) and magnetic coupler (M-type) to the modes of the ground plane, and both modes can be excited to the same amplitude by tuning the coupling-type. GMT, applied to the ground modes using inductor-connected metal strips, can generate a 90° phase difference between the two modes of the ground plane. The proposed antenna design generates a 6 dB axial ratio bandwidth of 140 MHz from 2.38 to 2.52 GHz in the <TEX>$+\textit {z}$</TEX>-direction. Right-hand CP and left-hand CP in the <TEX>$+\textit {z}$</TEX>-direction and <TEX>$-\textit {z}$</TEX>-direction, respectively, are obtained. The tuning mechanism is presented, and measurements are taken to validate the proposed technique.</P>