Unbroken Metal Rim Research Articles

Unbroken Metal Rim MIMO Antenna Utilizing Antenna Clusters

This letter presents an antenna system for mobile devices with an unbroken metal rim. By utilizing the characteristic mode analysis for the unbroken metal rim, efficient multiple-input–multiple-output operation can be achieved. The design is based on an antenna cluster technique that uses several coupled elements that are used to efficiently excite the modes of the rim. Nonresonant antenna elements and matching networks are used to couple to the metal rim. The design has small ground clearance of 5 mm and height of only 4 mm, and can operate in wide bandwidths both in 700–960 MHz low band and 1.56–4 GHz high band. Measurement results confirm that competent performance is achieved.

Single Ring Slot-Based Antennas for Metal-Rimmed 4G/5G Smartphones

In this paper, multiband antennas based on a single ring slot are proposed for 4G/5G smartphone applications. The basic structure of the antenna is consisted of a large metal ground and an unbroken metal rim, in which a single 2 mm-wide ring slots is realized between the metal ground and rim. Here, a reconfigurable 4G antenna (820–960 and 1710–2690 MHz) is initially devised by loading multiple grounded stubs and a simple dc controlling circuit with varactor diode into the upper section of the ring slot. To further cover the sub-6 GHz spectrum (3400–3600 MHz) for future 5G communications, a four-element multi-input multi-output (MIMO) slot antennas configuration is designed by utilizing the lower section of the ring slot. A prototype antenna was fabricated, and good agreement is shown between the measured and simulated results. Due to the advantages such as multiband operation, MIMO configuration for 5G communications, high isolation, and compact structure, the proposed antenna design is attractive for 4G/5G smartphones.

Parallel Dual-Loop Antenna for WWAN/LTE Metal-Rimmed Smartphone

A simple internal antenna design for wireless wide-area network/long-term evolution (LTE) operations is investigated, and it can be incorporated into a mobile phone that has an unbroken metal rim of height 5 mm. The proposed antenna is mainly composed of two parallel slots (dual loop) embedded on the system ground, and by feeding them with an L-shaped coupled feedline with matching networks, good excitation of multiple loop resonant modes can be obtained, which is capable of covering the GSM850/900 (824–960 MHz), DCS/PCS/UMTS2100, and LTE2300/2500 (1710–2690 MHz) operating bands. In addition, the feasibility of realizing decoupled multiantennas ( $2 \times 2$ multi-in multi-out antenna system) is also demonstrated, and its performances are acceptable for smartphone applications.

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.

Antenna design based on quasi‐degenerate characteristic modes of unbroken metal rim

A simple and efficient antenna technique for both single antenna and multiple-input multiple-output (MIMO) antenna design utilising an unbroken metal rim is analysed in the frequency band <1 GHz for mobile phone applications. A 110 mm × 55 mm × 5 mm unbroken metal rim has two characteristic modes (Modes 1 and 2) that resonate around 1 GHz, and these two modes are quasi-degenerate and orthogonal to each other. An uncontacting feeding structure is proposed to excite and utilise the characteristic modes of the unbroken metal rim for antenna radiation. In MIMO antenna design, it is possible to achieve high isolation and good diversity performance by properly exciting orthogonal modes with the proposed feeding technique. Two different cases for MIMO designs are presented to verify the feasibility of the proposed technique. In both two cases, the simulated isolation is ∼10 dB, and the 3:1 VSWR bandwidths for the MIMO antennas are wider than 150 and 60 MHz, respectively. The measured results show that the envelope correlation coefficients for each case are <0.2, indicating good diversity performance. The measured radiation patterns for the two MIMO antennas are orthogonal, again verifying the diversity performance.

Reconfigurable MIMO Antenna for Integrated-Metal-Rimmed Smartphone Applications

A reconfigurable full-metal-rimmed MIMO antenna is designed and proposed for WWAN/LTE smartphones. This antenna consists of two centro-symmetrically distributed antenna elements and radiation structures using the unbroken metal rim in plastic casing. It can achieve a good isolation of more than 17dB over the entire operation bands. Each antenna element occupies a small ground area of 30 × 6 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The U-shaped feeding line provides a coupled feed and the antenna element generates four typical loop resonant modes. Using reconfigurable technique to combine these four resonant modes, this hepta-band MIMO antenna can satisfactory cover lower bands of GSM850/900 and higher bands of GSM1800/1900/ UMTS/LTE2300/2500. A prototype MIMO antenna was fabricated and the measured results of S-parameters, antenna efficiency and gain, envelope correlation coefficient, mean effective gain, and channel capacity are reported.

Dual‐loop antenna with band‐stop matching circuit for WWAN/LTE full metal‐rimmed smartphone application

A dual-loop antenna for hepta-band wireless wide area network (WWAN)/long term evolution (LTE) narrow-frame full metal-rimmed smartphone application is proposed and studied. Compared with recent reported works, the main advantage of this design is the ability to achieve narrow-frame (smaller ground clearance) with unbroken metal-rim (or full metal-rimmed). Due to the modification of top no-ground portion, a band-stop matching circuit is used in this case to compensate the impedance mismatch caused by this modification. By combining the six resonant modes induced by the proposed dual-loop structure with the additional lower resonant mode excited by the matching circuit, the proposed antenna can successfully cover both WWAN bands (GSM850/900/DCS/PCS/UMTS2100) and LTE bands (LTE2300/2500). A prototype of the proposed antenna is fabricated, and the obtained results including reflection coefficients, efficiencies and gains are also presented and discussed.

A Dual-Loop Antenna Design for Hepta-Band WWAN/LTE Metal-Rimmed Smartphone Applications

A simple direct-fed dual-loop antenna capable of providing hepta-band WWAN/LTE operation under surroundings of an unbroken metal rim in smartphone applications is proposed. The greatest highlight of this proposed antenna is that it provides a simple and effective multiband antenna solution for an unbroken metal-rimmed smartphone. The unbroken metal rim with 5 mm in height embraces the system circuit board of 130 $\, \times \,$ 70 mm $^{2}$ . Two no-ground portions of 10 $\, \times \,$ 70 mm $^{2}$ and 5 $\, \times \,$ 70 mm $^{2}$ are set on the top and bottom edge of the system circuit board, respectively. In-between the two separate no-ground portions, there is a system ground of 115 $\, \times \,$ 70 mm $^{2}$ connected with the unbroken metal rim via a small grounded patch which divides the unbroken metal rim into two strips. Finally, a dual-loop antenna is formed by combining the inner system ground and two strips. This proposed dual-loop antenna is capable of covering GSM850/900/DCS/PCS/UMTS2100/LTE 2300/2500 operating bands. Detailed design considerations of the proposed antenna are described and both experimental and simulation results are also presented and discussed.

Novel Multiband Metal-Rimmed Antenna for Wearable Applications

A novel multiband antenna with an unbroken metal rim for wearable applications is presented. In order to achieve a wideband behavior, minimizing at the same time the size of the clearance area on the antenna ground plane, a novel feeding structure is proposed. This is achieved by connecting the metal rim to the ground plane thus allowing generating one lower-frequency resonance without occupying a large area. An additional resonance is then obtained using a suitable shorting patch. In this way, the proposed antenna presents a broadband behavior, while the width of the clearance area on the ground plane is of only 2 mm. The antenna performances in free-space and on a human phantom simulating a human body are analyzed by means of numerical simulations. Finally, the specific absorption rate (SAR) is analyzed to establish the antenna reliability in wearable applications. The experimental results demonstrate superior and stable performances of the metal-rimmed antenna when it is employed in wearable applications.

Slot Antenna for Metal-Rimmed Mobile Handsets

This letter introduces a 15.5 × 56.5-mm2 planar slot antenna operated under surroundings of an unbroken metal rim in mobile handsets. The height of the slot antenna is shortened, and the bandwidth for low band is expanded to cover both GSM850 and GSM900. This antenna provides a solution for planar unbroken metal-rimmed handsets and can be operated in five wireless communication bands (i.e., GSM850, GSM900, DCS1800, PCS1900, and UMTS bands). Good performances on return loss, radiation pattern, efficiency, and gain are obtained over these five operating bands. Hand effect of this slot antenna is also studied by comparison to the conventional monopole antenna.