Kurvinen, Joni; Lehtovuori, Anu; Mai, Jianchun; Wang, Chao; Viikari, Ville Metal-covered handset with LTE MIMO, Wi-Fi MIMO, and GPS antennas

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1 Pwered by TCPDF ( This is an electrnic reprint f the riginal article. This reprint may differ frm the riginal in paginatin and typgraphic detail. Kurvinen, Jni; Lehtvuri, Anu; Mai, Jianchun; Wang, Cha; Viikari, Ville Metal-cvered handset with LTE MIMO, Wi-Fi MIMO, and GPS antennas Published in: Prgress In Electrmagnetics Research C Published: 1/1/218 Dcument Versin Publisher's PDF, als knwn as Versin f recrd Please cite the riginal versin: Kurvinen, J., Lehtvuri, A., Mai, J., Wang, C., & Viikari, V. (218). Metal-cvered handset with LTE MIMO, Wi- Fi MIMO, and GPS antennas. Prgress In Electrmagnetics Research C, 8, This material is prtected by cpyright and ther intellectual prperty rights, and duplicatin r sale f all r part f any f the repsitry cllectins is nt permitted, except that material may be duplicated by yu fr yur research use r educatinal purpses in electrnic r print frm. Yu must btain permissin fr any ther use. Electrnic r print cpies may nt be ffered, whether fr sale r therwise t anyne wh is nt an authrised user.

2 Prgress In Electrmagnetics Research C, Vl. 8, 89 11, 218 Metal-cvered Handset with LTE MIMO, Wi-Fi MIMO, and GPS Antennas Jni Kurvinen 1, *, Anu Lehtvuri 1, Jianchun Mai 2,ChaWang 2, and Ville Viikari 1 Abstract Current phnes include mre metal than earlier, which deterirates the perfrmance f antennas. This paper presents the first cmplete antenna set designed fr a mdern handset with a full metal back cver. 4G, Wi-Fi, and GPS antennas are integrated int the metallic side frame f the device in a realistic mdel. The designed antennas are either capacitive cupling elements with reactive lads r slt antennas. Fixed matching circuits are used t imprve ttal efficiency. The passive implementatin enables the use f carrier aggregatin (CA) t increase the data rates, and includes als the multipleinput multiple-utput (MIMO) peratin fr 4G and Wi-Fi. The designed antennas cver frequency bands MHz, GHz, GHz, GHz, and GHz, prducing in measurements a gd agreement with simulatin results. 1. INTRODUCTION Mdern smartphnes have becme the everyday tl used als in demanding cnditins. Wireless netwrks have spread everywhere, s cnnectin can be established in any envirnment. Therefre, mbility f peple is nt restricted by the perfrmance f the devices anymre. Instead, mechanical strength is required frm the device t prtect itself and its subsystems frm physical damage. Als, frm industry-pint-f-view, cnsumer prducts have t be visually appealing. A recent trend amng phne manufacturers has been using metal cvers in flagship mdels t imprve bth the rbustness and aesthetics f the device. Hwever, using highly cnductive husing materials creates a challenge. Enclsing antennas with metallic structures prevents radiating and impedes establishing a cmmunicatins link. Prblems caused by the increased amunt f metal have been cuntered by new type f antennas that are integrated int the husing structure [1 7]. Previus studies have shwn prmising perfrmance with different antenna cnfiguratins. The first slutins include nly metallic side frame. Grunding the frame frm few lcatins creates a dual-lp antenna [1, 2], which excites several resnant mdes. Lp antennas generally have been a ppular chice as presented in [3 5, 9]. Als mnples integrated int the rim have been in use [6, 7, 1]. The next step frm metal-rimmed phnes is a metallic back cver. A larger vlume f metal increases the size f the RF-grund, which restricts the antenna size and placement pssibilities even mre. T ensure gd antenna perfrmance, phne manufactures have cut slts int the back cver, as is seen in many cmmercial prducts, r prpsed in, e.g., [11 17]. Sltless cvers have been presented in [18, 19], but they have large penings in the side rim fr the antennas. Anther challenge fr antennas cmes frm the current netwrk standards. Smartphnes must be able t perate n several frequency bands. Bands are wide, and cvering all f them requires many antennas. Utilizing multiple-input multiple-utput (MIMO) cmmunicatins and carrier aggregatin Received 23 August 217, Accepted 24 Nvember 217, Scheduled 8 December 217 * Crrespnding authr: Jni Kurvinen (jni.kurvinen@aalt.fi). 1 Department f Electrnics and Nanengineering, Schl f Electrical Engineering, Aalt University, Esp, AALTO FI-76, Finland. 2 AAC Technlgies C., Ltd., Nanjing 2193, China.

3 9 Kurvinen et al. (CA) techniques t achieve higher data rates als increases the number f antennas. In mbile devices, the space available fr antennas is very limited due t the cmpact physical dimensins and maximized size f a tuchscreen. Altgether, these practical aspects make it mre difficult t achieve gd perfrmance. One prmising apprach in multiantenna design is t use the thery f characteristic mdes [8]. This paper presents a multiband antenna system fr a realistic smartphne with fully metallic back cver. Antennas cver LTE lw band (LB, MHz), LTE high band (HB, MHz) and Wi-Fi (2.4 GHz, 5 GHz) bands with MIMO and CA capability. In additin, the design als supprts GPS (1.575 GHz) peratins. As far as we knw, this is the first study presenting a cmplete antenna slutin fr a metal-cvered handset. Althugh the designed antenna structures are well-knwn, the nvelty here is the used antenna cmbinatin that fits inside a smartphne and prvides decent perfrmance. Figure 1 presents the main parts f the simulatin mdel and the detail in the used mdel. Our design has fixed antenna structures and matching circuitries fr all frequencies, sltless metallic back cver, metallic side frame, and realistic phne mdel with subsystems, which are generally nt included in recent papers. Table 1 lists all antennas and their peratinal frequencies. Antennas integrated int the side frame Camera USB Middle frame, battery, and grunding pins Sltless back cver Plastic ring Figure 1. Explded view f the simulatin mdel. Table 1. Operatinal frequencies f each antenna and their respective prts in the simulatin mdel. Antenna Frequencies (MHz) Prt Main LB Main HB Diversity HB Diversity LB Wi-Fi , GPS & Wi-Fi , , Operatinal principle f the design is intrduced in Sectin 2. Sectin 3 presents the prpsed antenna slutins in detail with impedance matching results. The efficiency results and MIMO perfrmance frm simulatins and measurements are presented in Sectin 4. Sme cnclusins are givensectin5.

4 Prgress In Electrmagnetics Research C, Vl. 8, DESIGN FRAMEWORK AND PRINCIPLES This study aims t design a realistic structure, and hence we use a very accurate simulatin mdel frm the beginning. The mdel includes als many realistic details such as battery, USB-prt, and frnt camera, as shwn in Figure 1. A plastic rim separates the back cver and side frame frm each ther. A large middle frame is in the center f the device mdeling the tuchscreen and ther electrnics f the phne, and it als acts as the RF-grund fr the antennas tgether with the back cver. Similar realisticity f design mdel is earlier seen in [14, 15]. The size f the device is mm 3, which is rughly the same as that f, e.g., iphne 7 Plus r Samsung Galaxy S7 edge s. Grund clearance between the middle frame and the side frame is 2.5 mm in the sides, and 1.2 r 7.8 mm in the ends. The key prperty f the mdel is the sltless metallic back cver, seen in Figure 2(a). Main HB Wi-Fi Main LB Diversity LB and HB 151 (a) (b) GPS/Wi-Fi 2 Figure 2. Simulatin mdel shwing the sltless back cver and physical dimensins in mm in (a), and the lcatin f each individual antenna in (b). Maximum thickness f the device is 7.63 mm. The prpsed antennas are f Capacitive Cupling Element (CCE) type [2, 21], r slt antennas. CCEs are widely used at cellular frequencies due t their wide frequency band and rbust perfrmance. Slt antennas are apprpriate fr sides f the phne with nly narrw 2.5 mm clearance fr antennas [1, 3]. Each antenna has additinal matching circuit t adjust the resnances t desired frequency bands and t enhance perfrmance. Matching cmpnents in simulatins are mdels f actual Murata inductrs and capacitrs (LQW18 and GQM18 series, respectively). Antenna structures are studied by cnducting electrmagnetic simulatins in CST Micrwave Studi [22]. Matching circuitry is created and ptimized in Optenni Lab [23]. Table 1 lists all designed antennas and als their respective prt numbers in the simulatin mdel. Same prt numbers are later used in this paper when presenting the perfrmance f the antennas. Since the simulatin mdel cnsists f realistic shapes and details, the cmputing times f EMsimulatins becme very lng. Therefre, antennas are designed and simulated in the first phase ne by ne t reduce simulatin times. Lw cupling between different frequencies allws this methd, and all antenna elements and prts can be taken int accunt nly in the last simulatins when fine-tuning the dimensins f structures and matching cmpnent values. Implementatin f the antennas starts with the cellular antennas. One end f the device is reserved fr the main antenna, and the ther ne fr the diversity antenna. Figure 2(b) shws the final psitins f the antennas. First, we design the lw band f the main antenna since lwer frequencies are the mst challenging and require the largest physical size. Secnd, a slutin fr the main HB is added. The main antenna structure has been the basis f the diversity antenna fr MIMO capability. The last antennas t include are the GPS and Wi-Fi antennas perating at higher frequencies. They are lcated at the lng sides f the device. Fr imprved perfrmance in the final design, LB and HB f the main antenna are separated t individual cnfiguratins such that HB is placed t the side rim and LB utilizes the end cmpletely. Matching netwrks fr each element are adjusted cntinuusly when structural changes are made.

5 92 Kurvinen et al. The aesthetic prperties expected frm a real device have been in the guideline and a restricting factr in the design prcess. Fr example, the width f all cuts in the metal rim is 1 mm in the sides and 2 mm in the ends. In additin, the slts are lcated as symmetrically as pssible arund the device, t keep in mind the visual appearance f a pssible end-prduct. The cntinuus metal rim is required t g arund the device, which has determined the antenna structures Three-element Antennas in the Ends f the Phne Main and diversity antennas are based n the clsely lcated antenna elements [24] that cuple strngly t each ther and the grund plane, which imprves impedance matching [24, 25]. Hwever, mutual cupling between prts decreases efficiencies. The negative effects f large mutual cupling are cuntered with careful matching circuit design in the final slutins. Matching circuit design is dne by defining pass- and stp-bands fr each prt in Optenni Lab. This way the radiated pwer is maximized and mutual cupling reduced. Operatinal bandwidths f these antennas are imprved with grunding inductances. Similar reactive lading is used, e.g., in [26, 27] Slt Antennas n the Sides f the Phne The antennas fr higher frequencies are implemented as slt-type antennas n the sides f the phne. Figure 3 presents the basic principle f the slt antennas. The metal rim is grunded by cnnecting t the middle frame f the device. The slt is cut t the grunding metal, and als t the side rim. Slt antennas are applicable with very small clearance. A Slt B Metal rim Grunding Middle frame C Feed pin Grunding Figure 3. Principle f a slt antenna illustrated frm the tp f the phne. The tw branches (A and B) separated with a 1 mm cut in the metal rim are the main resnatrs f this design. The resnant frequencies can be tuned by changing the lengths f A and B. Basically, this means enlarging the clearance area (dashed area in Figure 3), s that the width and lcatin f the slt with respect t the chassis remain the same. Fr example, in the case f a Wi-Fi antenna, tuning the length A affects the 5 GHz band and length B the 2.4 GHz band. Generally, the lnger ne branch is, the lwer its resnance frequency becmes. By adjusting the feed lcatin, i.e., length C, the matching levels can be balanced. 3. PROPOSED ANTENNAS Traditinally, mbile antennas are required t have 6 db matching level. Nwadays, the design framewrk is mre cmplex, as the clearances are smaller and industry sets strict cnstraints t the aesthetics. Thus, the same matching level is challenging t achieve [14, 15]. Therefre, we have fcused n realizing mderate impedance matching at crrect frequency bands, and maximizing the efficiencies, which are presented in Sectin 4. Next, the antenna structures are intrduced in detail with impedance matching results Main Antenna The LB and HB f the main antenna have been implemented as separate structures. Figure 4 shws the gemetry f the LB antenna. The structure cnsists f tw L-shaped parts in the side rim and

6 Prgress In Electrmagnetics Research C, Vl. 8, Prt Prt 3 Prt 2 Prt nh 6.2 pf 3.6 nh 5.6 nh 12 nh Prt 2 Prt 3 Figure 4. Cnfiguratin fr main cellular antenna s lw band peratin. Prt 1 is fed thrugh a matching circuit shwn n the right, and aperture matching elements in Prts 2 and 3 are grunded with inductances. All dimensins are in mm Prt Prt nh 2.2 nh 1.1 pf Figure 5. Main antenna cnfiguratin fr high band peratin frm tpside f the phne. The used matching circuit is seen n the right. All dimensins are in mm. Matching level (db) S11 S Figure 6. Matching levels fr the main cellular antenna. parasitic cupler n the frnt face f the phne. The feed is cnnected t larger L-shaped element (Prt 1), and aperture matching elements are cnnected with grunding inductances t Prts 2 and 3. The dimensins f the elements are ptimized tgether with circuit elements t achieve the desired peratin. In rder t get mre freedm t design, HB antenna is implemented with a slt antenna as shwn in Figure 5. The metal rim arund the phne is cut with 1 mm slt, and the rim is grunded t the middle frame frm unnecessary areas frm antenna pint f view. This grunding als significantly imprves the islatin between antennas. Previusly published designs use additinal slts in the back cver [11 13] t imprve the perfrmance at remarkable way. Therefre, in this design maximizing efficiency has been the main design target, since the sltless cver makes achieving 6 db matching level practically impssible. Figure 6 shws that the main antenna reaches mainly 3 db matching level ver bth peratinal bands.

7 94 Kurvinen et al Diversity Antenna The diversity antenna fr MIMO cmmunicatins is lcated at the ppsite end f the phne ther than the main antenna. This structure shwn in Figure 7 has the same basic idea as the main LB antenna, but nw bth L-shaped elements are fed. With suitable matching circuits Prt 4 cvers HB while Prt 5 perates the LB. The triangle at ne end f the parasitic cupler cnnected t Prt 6 is intrduced t fine-tune the resnances and enhance the desired perfrmance. The triangle makes the parasitic element behave lnger electrically, which lwers the highest resnances frm ut-f-the-band frequencies t the crrect range. Idea fr this extensin is based n [28], in which trapezidal feeds are used t achieve wider peratinal band Prt 4 3 Prt pf 6.2 nh 8.2 nh Prt Prt nh 3.6 nh 5.6 pf Prt nh Prt 6 Figure 7. Gemetry and matching circuitry fr diversity cellular antenna. Prt 4 is fr LB and Prt 5 fr HB. Prt 6 is fr aperture matching. All dimensins are in mm. Figure 8 shws the matching levels f the diversity antenna. Cmpared t the main antenna, the impedance matching level is abut 1 db lwer, because due t the structural nn-symmetries (camera, USB, and grund clearance) the ends f the phne are different, and hence the vlume available fr the antennas is different. Mrever, in the diversity antenna, LB and HB are realized with the same structure, which further restricts the usable vlume. The structural differences between the tw ends d nt allw the same separatin f LB and HB t used als in the diversity antenna. Als the side parts f the L-shaped elements are lnger in the main antenna, which partly explains the different perfrmance. Matching level (db) S44 S Figure 8. Matching levels fr the diversity cellular antenna GPS and Wi-Fi Antennas Nwadays mbile phnes have t supprt GPS and Wi-Fi. Antennas fr this are lcated n the lng sides f the device, and are similar slt antennas as the main cellular HB antenna. Detailed dimensins f Wi-Fi 1 and GPS/Wi-Fi 2 antennas are shwn in Figure 9. Bth f the antennas supprt Wi-Fi at 2.4 GHz and 5 GHz bands, and ne f the tw perates als n GPS band at GHz as seen in Figure 1.

8 Prgress In Electrmagnetics Research C, Vl. 8, (16.5) 14.5 (28).5 pf.5 pf 2.5 Prt 7 Prt 9 Prt 7 (9) 3.5 (1) 3 nh 16 nh 8.2 nh 1 nh Figure 9. Antenna cnfiguratin frm the tp f the phne fr Wi-Fi 1 antenna in Prt 7. The dimensins in the parentheses are fr GPS/Wi-Fi 2 antenna in Prt 9. Matching netwrks fr bth antennas are seen n the right. All dimensins are in mm. Matching level (db) Matching level (db) S77 S Figure 1. Matching levels fr GPS and Wi-Fi antennas. Figure 1 shws the matching levels f Wi-Fi and GPS antennas. In cntrast t cellular antennas, these btain at least 5 db matching ver the desired bands Antenna Islatin Especially at the lw band achieving gd antenna islatin is difficult as the grund plane acts as the main radiatr fr tw antennas. Figure 11 shws the simulated cupling at the cellular frequencies. Generally, the fur antenna prts are well-islated as the cupling levels are 15 db r better. As expected, due t the cmmn antenna structure, the largest cupling S 54 is between diversity LB and HB. Still, they are well-islated as the mutual cupling is belw 12 db ver the whle frequency bands. Figure 12 shws the cuplings at the GPS and Wi-Fi frequencies. Clearly, the cellular antennas Cupling (db) Figure 11. Cupling at cellular frequency bands S41 S51-4 S81 S54 S84 S

9 Kurvinen et al Cupling (db) Cupling (db) S71 S94 S S 91 S 75 S S74 S95 S Figure 12. Antenna cupling between cellular and Wi-Fi antennas. are well-islated in these bands as the peratinal frequencies are different. Since the distance between Main HB and Wi-Fi 1 antennas is physically and electrically very small (see Figure 2(b)), the cupling between the tw antennas (S87 ) in their shared peratinal band is larger than in ther cases, peaking at 11 db. Althugh the antenna islatins are generally already n very gd levels, they culd pssibly be imprved further by embedding metamaterial structures [29, 3]. 4. ANTENNA PERFORMANCE The main target f this study is t achieve decent ttal efficiencies, at least 3%, in simulatins fr each individual antenna. In additin, MIMO and CA capabilities are analyzed with envelpe crrelatin cefficient (ECC). T cnfirm the btained simulatin results, a prttype f the structure is manufactured and then measured. The middle frame (see Figure 1) and parts cnnected t it, including the grunded side antennas, are made f slid brass by milling. The back cver is made frm aluminum. Tp.8 mm f the middle frame is replaced with an FR-4 printed circuit bard (PCB), n which the R L335 [31], matching circuits are realized. Plastic ring is made f injectin mldable plastic PREPERM whse dielectric cnstant is 3.35 and lss tangent.5. The cnstructed prttype and measurement setup is shwn in Figure 13. (a) (b) (c) Figure 13. Cnstructed prttype (a) withut and (b) with the PCB and frnt face elements. Drilled hles seen in (a) are used fr attaching the back cver and PCB t the middle frame. (c) The measurement setup in Satim StarGate with the used crdinate system.

10 Prgress In Electrmagnetics Research C, Vl. 8, Radiatin Perfrmance Current transmitters tlerate a significant amunt f impedance mismatch, and hence the antenna perfrmance is mainly dminated by the radiatin efficiency. Due t large amunts f metal in this structure, the matching levels f especially cellular antennas remain rather mdest. Hereby the verall perfrmance is analyzed by ttal antenna efficiency. Figure 14 shws simulated ttal efficiencies fr all designed antennas, cmpared with measured results. Efficiency (%) LB HB Efficiency (%) LB HB Efficiency (%) (a) Efficiency (%) (b) Wi-Fi 1 Wi-Fi 2/GPS (c) Figure 14. Ttal efficiencies fr (a) main, (b) diversity, and (c) GPS and Wi-Fi antennas. Slid lines are simulated and dashed lines measured efficiencies. Fr the main antenna, simulated ttal efficiencies are 3 4%, as shwn in Figure 14(a). Diversity antenna with slightly different design perfrms with 2 4% efficiency (Figure 14(b)). These simulated results are in line with impedance matching results. In recent publicatins, cellular antennas in metal-cvered phnes typically reach efficiencies ver 4% [11 13, 19]. Althugh the simulated efficiencies are lwer than thse values, the target level f 3% fr ttal efficiency is mainly achieved. Hwever, ur mdel is mre realistic and has the sltless back cver, which is nt seen in previus papers. Therefre, it is mre cnvenient t cmpare ur results with [14, 15], which present slutins f similar realisticity. Our measured efficiencies cnfirm the simulatins very well. Mrever, LB f the main antenna is even better than in simulatins, peaking at 5%. Main HB and diversity antennas are very similar with simulatins with efficiencies ranging between 2 4%. A small frequency shift is bserved as all bands appear at slightly higher frequencies in measurements than in simulatins. In [14, 15], generally the same measured efficiency levels are reached, but with tunable slutins. Wi-Fi and GPS antennas perfrm very well in the simulatins, as Figure 14(c) shws. Bth antennas reach at least 4% and up t 8% ttal efficiency. In measurements, we ntice similar but strnger frequency shift t the higher frequencies as with cellular antennas. Especially Wi-Fi 2 antenna is shifted up at 2.4 GHz being cmpletely ut f the band. By adjusting cmpnent values, r including mre circuit elements t the matching netwrk, the resnance can be mved t the desired band withut

11 98 Kurvinen et al. z x z y xz -plane xz -plane xz -plane xz -plane x y yz-plane yz-plane yz-plane yz-plane (a) yx-plane (b) 15 yx-plane (c) 15 yx-plane (d) 15 yx-plane (e) 15 Figure 15. Cutting planes (a) and radiatin patterns f cellular antennas at (b) 83 MHz, (c) 23 MHz, and Wi-Fi antennas at (d) 24 MHz, and (e) 55 MHz. Blue curves crrespnd t the main r Wi-Fi 1 antenna, and red t the diversity r Wi-Fi 2 antenna. Slid lines are the measured fields and dashed the simulated. Unit is db LB HB Wi-Fi ECC.6.4 ECC Figure 16. Simulated (slid lines) and measured (dashed lines) envelpe crrelatin cefficients fr all MIMO antennas. hurting the peak efficiencies. Generally, the measured GPS and Wi-Fi efficiencies are 4 6%, and are in the same range as in [13, 18]. Measured and simulated nrmalized radiatin patterns are shwn in Figure 15. Figure 15(a) illustrates the rientatin f the phne in each plane. In xz- andyx-planes, the metal cver is in the right side f the device. The measured patterns match the simulatins very well. In mst cases, the antennas radiate nicely in all directins, althugh sme strng nulls are bserved.

12 Prgress In Electrmagnetics Research C, Vl. 8, MIMO/CA Capability T analyze the MIMO/CA perfrmance f the designed antennas, Envelpe Crrelatin Cefficients (ECC) [32] are calculated frm far-field results fr each MIMO antenna pair. Figure 16 shws simulated and measured ECCs in each case. The crrelatin in the high band and Wi-Fi frequencies is minimal. As can be expected, ECC is the highest at the lw band. This is due t the cupling f antennas t the chassis. Similarly, the strngest crrelatin f HB and Wi-Fi antennas appears belw 1 GHz, even thugh the antennas d nt perate at that frequency range. The crrelatins calculated frm the measured fields are in gd agreement with simulatins, but at clearly better levels. Generally, ECC is required t be belw.5 fr the antennas t be suitable fr MIMO and CA peratins. The measured peak crrelatin f LB antennas is nw.4, which satisfies the general requirement fr MIMO. In HB and Wi-Fi bands, the crrelatins are even less, staying at belw.2. Due t the fixed antenna structures and gd ECC, the designed antennas can be used in CA applicatins as well State-f-the-Art Cmparisn Table 2 presents a cmparisn between the prpsed design and ther previusly published antenna systems fr metal-cvered handsets. This cmparisn highlights the fact that ur design is the first MIMO-capable, cmplete antenna system fr metal-cvered handsets. Mst f ther designs d nt have any MIMO, and many perate n fewer frequencies. Mrever, the LTE LB starts frm 7 MHz in ur design, which is nt the case with many ther systems. In additin, we achieve similar perfrmance with fixed antenna and matching structure, while sme require tunable slutins. Table 2. Cmparisn f prpsed design and previusly published antennas in metal-cvered handsets. LB frm 746 MHz upwards, LB frm 85 MHz upwards, HB up t 22 MHz, # nly 2.4 GHz Wi-Fi, includes nly metal rim, simulated value. Ref. This wrk Operatinal bands LTE LB & HB, GPS, Wi-Fi Measured efficiency 2 6% MIMO capability LB, HB, Wi-Fi Measured ECC LB <.4, HB <.1 Antenna implementatin Fixed [11] LTE LB &HB 28 72% LB, HB <.19 Fixed [13] LTE LB &HB, GPS, Wi-Fi # 4 65% - - Fixed [14] LTE LB & HB 2 55% - - Tunable [15] LTE LB & HB 2 5% - - Tunable [17] LTE LB & HB 4 7% - - Fixed [18] GPS, Wi-Fi 4 7% - - Fixed [2] LTE LB & HB 45 9% HB <.5 Fixed [8] LTE LB 25 4% LB <.1 Fixed [9] LTE LB & HB 45 9% LB, HB LB <.18, HB <.1 Tunable 5. CONCLUSIONS This paper presents a realistic metal-cvered handset design with LTE, GPS, and Wi-Fi antennas including MIMO peratin. The prpsed structure is the first cmplete antenna system fr fully metal-cvered smartphne. In spite f the huge effect f a cntinuus metal cver, the acceptable efficiency perfrmance is achieved withut tunable circuit cmpnents. Especially, the design takes int accunt many essential cmpnents f the real device. Als, the design is capable f carrier aggregatin in the cellular bands due t the fixed antenna and matching structures.

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