Hepta‐band coupled‐fed antenna for metal‐ring‐frame WWAN/LTE smartphone applications

A small‐size 40 mm × 10 mm coupled‐fed antenna for hepta‐band WWAN/LTE metal‐ring‐frame (MRF) smartphone applications is investigated. Unlike conventional solutions that remove the redundant resonances excited by the MRF, the proposed antenna makes full use of the MRF resonances. By meticulously co‐design the antenna and MRF, multi‐resonance frequencies are excited and integrated, which results in achieving hepta‐band operation for an MRF smartphone antenna. Detail design considerations and experimental results of the proposed antenna are provided and analyzed. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:633–639, 2016.     

Compact dual‐band antenna based on CRLH‐TL for WWAN/LTE terminal applications

In this article, a compact dual‐band antenna based on composite right/left‐handed transmission line (CRLH‐TL) is proposed for WWAN/LTE wireless terminal applications. By using 2 symmetrical CRLH structures, the proposed antenna can easily produce 2 wide separate operating frequency bands with a compact size of 25 × 25 × 6 mm³. Additionally, a pair of matching strips is introduced on both sides of the feeding line to further improve the impedance characteristics of the terminal antenna. The experimental results demonstrate the proposed antenna is capable of working over the frequency ranges of 0.66‐1.06 GHz and 1.68‐2.88 GHz with |S₁₁| < ?6 dB, which can cover the bands of LTE700, GSM850, GSM900, GSM1800, GSM1900, UMTS, LTE2300, and LTE2500 for wireless terminals. Moreover, the multiple input multiple output (MIMO) operating performance of the proposed antenna element is also studied, and an enhanced isolation between the antenna elements is obtained by utilizing the defected ground structures and grounded branches.     

Dual‐band circularly polarized multiple‐input multiple‐output antenna for GSM and lower LTE applications

A circularly polarized multiple‐input multiple‐output (MIMO) antenna is presented for global system for mobile (GSM) (710 MHz) and lower long term evolution (LTE) (900 MHz) frequency bands. The antenna consists of four ports with four impedance transformers on the bottom substrate and elliptical rings on the upper substrates. Impedance transformers include open stub and irregular microstrip lines in order to control impedance matching and resonant frequencies. Two upper substrates that contain orthogonal elliptical rings cause the circular polarization property of the proposed antenna. The results of measurement for the presented antenna show its performance with S‐parameters of less than ?10 dB in the frequency ranges of 699‐750 MHz for GSM and 880‐1115 MHz for lower LTE applications. Also, the gain and radiation efficiency are higher than 5dBi and 70%, respectively.     

A Dual‐band and dual‐polarized antenna array for 2G/3G/LTE base stations

A dual‐band antenna array is proposed for the application of base station (BS) in 2G/3G/long term evaluation (LTE) mobile communications. This antenna consists of two independent ±45° dual‐polarized arrays, one of which operates from 1.71 to 2.17 GHz, and the other of which is designed from 2.5 to 2.69 GHz. The proposed BS antenna array has a high isolation of greater than 29 dB and high front‐to‐back ratio of more than 26 dB at the operating frequencies. The measured peak gain is 17.9 and 18.1 dBi for the lower and upper bands, respectively, and the cross polarizations isolation (CPI)(within ±60º of the mainlobe) is 16 dB lower than the broadside co‐polarization. It was confirmed that the proposed antenna array meets the communication standards in China. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:154–163, 2016.     

Slot line fed dual‐band dipole antenna for 2.4/5.2 GHz WLAN applications

A printed slot line fed dual‐band coplanar dipole antenna having a dimension of 0.40λ_g × 0.20λ_g suitable for both 2.4 and 5.2 GHz (IEEE 802.11 b/g and 802.11 a) WLAN application is presented. The structure comprises of a slot line fed symmetrical L strips to achieve dual‐band operation. Design equations of the antenna are developed and validated on different substrates. The simulation and experimental results show that the proposed antenna exhibits good impedance match, gain, and stable radiation patterns in both the frequency bands. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE , 2012.     

Dual‐band quasi‐self‐complementary antenna for wireless local network operation

This article proposes a compact (6 × 21 × 0.4 mm³) antenna with dual‐band operation that satisfies the wireless local area network. To achieve optimal impedance matching for the lower and upper operating bands, the proposed antenna structure is designed as a quasi‐self‐complementary (QSC) type, in which the lower (2.4 GHz) operating band is excited through the loop‐like structure of the proposed antenna, whereas its self‐complementary counterpart (rectangular patch structure) induces the upper (5.2/5.8 GHz) operating band. Further investigation was also conducted by printing the proposed QSC antenna onto a flexible substrate of 0.063 mm in thickness. To cover both operating bands, the proposed flexible antenna was restructured to 20.5 × 8 mm². The design and initial characteristics of the two proposed antennas were discussed in detail via simulation, and the experimental results showed satisfactory performance of both operating bands. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:298–305, 2014.     

A compact planar inverted‐F antenna with U‐shaped strip for all‐metal‐shell handset application

A compact dual‐band planar inverted‐F antenna (PIFA) with U‐shaped strip is proposed in this work for all‐metal‐shell mobile telephone application. As metal‐shell handsets are getting more and more popular nowadays, it raises a big challenge in antenna design as the metal‐shell associated with surrounding electronic components like front‐back‐cameras and telephone receiver would affect the antenna performance. This work provides an optional solution to alleviate this problem, where the metal shell of the handset and a U‐shaped strip are utilized as part of the antenna. The proposed antenna is able to generate radiation at 2.4 GHz for Wi‐Fi application with the help of the metal shell while using the U‐shaped strip can achieve a resonance at 1.575 GHz for GPS application. A prototype has been fabricated to verify the radiation performance in a practical handset test environment.     

Dual‐band circularly polarized dielectric resonator antenna for wireless applications

This letter investigates an integrated antenna configuration for WLAN/WiMAX applications. The proposed composite antenna configuration is simply the grouping of ring dielectric resonator along with reformed square‐shaped slot antenna. Three significant characteristics of proposed article are: (1) aperture act as magnetic dipole and excite HE_11δ mode in ring dielectric resonator antenna; (2) reforming of square aperture generates orthogonal modes in ring DRA and creates CP in lower frequency band; (3) annular‐shaped Microstrip line along with reformed square aperture creates CP wave in upper frequency band. With the purpose of certifying the simulated outcomes, prototype of proposed structure is fabricated and tested. Good settlement is to be got between experimental and software generated outcome. Experimental outcomes show that the proposed radiating structure is operating over 2 frequency bands that is, 2.88‐3.72 and 5.4‐5.95 GHz. Measured 3‐dB axial ratio bandwidth in lower and upper frequency band is approximately 9.52% (3.0‐3.4 GHz) and 5.85% (5.64‐5.98 GHz), respectively. These outcomes indicate that the proposed composite antenna structure is appropriate for WLAN and WiMAX applications.     

A compact dual‐band filtering antenna for wireless local area network applications

A printed dual‐band filtering antenna with decent frequency selectivity at 2.45 and 5.2 GHz for wireless local area network (WLAN) applications is developed. The filtering antenna is compact, which comprises a tapped feed line, two dual‐band stub‐loaded open‐loop resonators, and a dual‐band bended monopole. It can be easily printed on a single layer PCB substrate with low profile and low cost. The entire structure is very simple compared with the previously reported dual‐band filtering antennas that requiring multi‐layer structures. The monopole functions as not only a radiator, but also the last resonator of a dual‐band filter. The developed antenna exhibits good frequency selectivity and out‐of‐band suppression. In addition, the two operation bands can be adjusted relatively individually. The proposed antenna is optimized and fabricated. The experimental results show it has good frequency selectivity at both 2.45 and 5.2 GHz, wide bandwidth 11.8% and 7.8%, and excellent out‐of‐band suppression.     

A dual‐band eight‐antenna multi‐input multi‐output array for 5G metal‐framed smartphones

A dual‐band eight‐antenna array operating in the long‐term evolution (LTE) band 41 (2.496‐2.69 GHz) and 3.5‐GHz band (3.3‐3.7 GHz) for fifth‐generation (5G) metal‐framed smartphone is presented. The proposed dual‐band antenna array is composed of four identical dual‐antenna building blocks (DABBs). Each DABB consists of two identical antenna elements with a neutralization line between them. The antenna array is simulated, fabricated, and measured. The isolations are better than 10.5 dB and 11.0 dB in the low band (LB; LTE band 41) and high band (HB; 3.5‐GHz band). The total efficiencies are 41% to 54% and 46% to 64% in the two operation bands, respectively. In addition, the measured envelope correlation coefficients are less than 0.11 and 0.06, the calculated channel capacities are better than 34.5 and 36.3 bps/Hz in the LB and HB, respectively. Furthermore, four hand‐grip scenarios are investigated, and results show that proposed antenna array can maintain excellent multiple‐input multiple‐output performances in all scenarios.     

Dual‐band dual‐sense circularly polarized antenna based on crossed dipole structure for WLAN/WiMAX applications

This paper presents a new approach to design dual‐band antenna with dual‐sense circularly polarized (CP) operation. A principle for CP radiation is the use of two orthogonal dipoles and properly choosing their lengths can produce either right‐hand CP (RHCP) or left‐hand CP (LHCP) operation. In the proposed structure, the lower frequency band at 2.4 GHz is designed with RHCP radiation and LHCP is the operating mode of the higher band at 3.5 GHz. For verification, an antenna prototype is fabricated and measured. Measured data indicate that good performances over the RHCP and LHCP bands can be obtained with usable bandwidths of 2.9% (2.36‐2.43 GHz) and 1.7% (3.48‐3.54 GHz). Along with this, it also observes good unidirectional radiation patterns and the measured broadside gains are around 7.7 and 7.4 dBic across these frequency ranges.     

Dual‐band dual‐polarized hybrid aperture‐cylindrical dielectric resonator antenna for wireless applications

A dual‐band dual‐polarized hybrid aperture‐cylindrical dielectric resonator antenna (CDRA) is examined in this article. Inverted regular pentagon shaped aperture is not only used to launch two radiating hybrid modes (HEM_11δ and HEM_12δ mode) in CDRA but also act as a radiator. Out of two frequency bands, the lower frequency band is linearly polarized while upper frequency band is the combination of both circular and linear polarization. A circular polarization (CP) characteristic in upper frequency band is created by loading quarter annular stub with microstrip line. LHCP/RHCP can easily be controlled by alternating the position of quarter annular stub. It is operating over two frequency ranges i.e. 2.48‐2.98 GHz and 4.66‐5.88 GHz with the fractional bandwidth 18.31% and 23.14% respectively. Axial ratio bandwidth (3‐dB) is approximately 8.78% (4.9‐5.35 GHz) in upper frequency band. The proposed antenna design is suitable WiMAX (2.5/5.5 GHz) and WLAN (2.5/5.5 GHz) applications.     

Design of multi‐band antenna for LTE wearable device with shared slots and radiators for smart watch

In this study, multi‐band antenna for LTE wearable device with shared slots and radiators for smart watch was present. This study incorporated 4G communication frequency bands, a GPS positioning system, and BT/Wi‐Fi in a 43.6 × 43.6 × 5.8 mm³ metal case to achieve satisfactory radiation fields and performance efficiency within a small space. This article presents an overview of the theory. There are four ports in the system. Frist, Port 1 is a low‐frequency antenna offering LTE 700 and GSM 850/900. The maximal gain and efficiency are respectively 3.9 dBi and 82%. Second, Port 2 is a high‐frequency monopole with a winding long path on the side of the frame to achieve a reflection loss bandwidth that fully encompasses GSM 1800/1900/UMTS and LTE 2300/2500. The maximal gain and efficiency of this port are respectively 5.3 dBi and 92%. There are also have GPS (Port 3) and Wi‐Fi (Port 4) antenna implement IFA and loop excitation mechanisms, respectively. This antenna system can fulfill the market demand. As confirmed through both simulation and measurement, the antenna can cover LTE bands. Increasing the path capacity of a MIMO system to increase the transmission speed is a crucial focus in mobile communication research and development.     

A uniplanar printed antenna with an inverted L‐shaped coupling feed for LTE/GSM/DCS/PCS/UMTS operations

A novel uniplanar printed antenna with a total size of 115 × 40 mm² is proposed for mobile device application. By using an inverted L‐shaped feeding mechanism and a meandered shorting strip, a dual‐band operation with wideband characteristic can be achieved. Here, the lower operating band is able to cover the LTE 700 and GSM 850/900 operations, while the higher operating band allows DCS 1800, PCS 1900, UMTS, and LTE 2300 operations. Furthermore, in order to increase the bandwidth of the higher operating band so that LTE 2500 operation can also be covered, an additional parasitic stub is attached to the feed line to excite a resonant frequency at around 2.72 GHz. Parametric studies via simulation are carried out, and prototype of the proposed antenna is also experimentally investigated to validate the simulated results. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2012.     

A novel uniplanar antenna with dual wideband characteristics for tablet/laptop applications

A novel uniplanar antenna design for tablet/laptop applications is proposed. The proposed antenna with a size of 68 × 12 × 0.8 mm³ is comprised of three strip sections, namely, the feeding strip, parasitic shorted strip, and tuning stub strip (or printed LC matching circuit). Five resonant modes are induced by the proposed antenna, and they are combined to yield two wide operating bands that have 6‐dB return loss bandwidths of more than 50% (695‐1190 MHz and 1690‐2930 MHz). Thus, the proposed antenna can easily cover the entire LTE/WWAN operations working in the 698‐960 MHz and 1710‐2690 MHz bands. Besides demonstrating good radiation efficiency of more than 60% for the two wide operating bands, the proposed antenna also exhibits reduced ground effects, in which reducing the ground size will not deteriorate the antenna's performances.     

Miniaturized dual‐band dielectric resonator antenna for IEEE 802.16d fixed WiMAX applications

A miniaturized dual‐band C‐shaped dielectric resonator antenna (DRA) with partial ground plane is presented for IEEE 802.16d fixed WiMAX applications at 3.5 and 5.8 GHz. The design starts with dimensioning a single band cylindrical DRA, which has been transferred to get a dual‐band ring‐shaped DRA. One portion of the ring‐shaped DRA is removed for forming a C‐shaped DRA to get a more compact antenna. For easy fabrication, the compact DRA dimensioned as 60 × 50 × 6.6 mm³ is excited by a microstrip line feeding. The design parameters are inner and outer radii of the C‐shaped antenna and air gap (between DR and ground) to control both the resonating frequency and the quality factor. The result shows peak gain around 3.26 and 5.55 dBi at 3.5 and 5.8 GHz, respectively. The obtained results indicate very good agreement between the simulated and measured results. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE 22: 682–689, 2012.     

An inverted‐F antenna design for WLAN/WiMAX dual‐network applications

This study designed a compact size (45 mm × 9 mm × 1.6 mm) stand‐alone dualband inverted‐F antenna (IFA) printed on a low‐cost FR4 substrate for dual‐network WLAN (2.4/5.2/5.8 GHz) and WiMAX (2.5/3.5/5.5 GHz) operating bands. To achieve broad 10‐dB bandwidth of more than 45% and 31% for the lower and upper operating bands, respectively, the techniques of shorting the open‐end of the microstrip feed line to the driven monopole and loading a C‐shaped parasitic element with dissimilar arm lengths into the opposite side of the IFA were introduced. Further experimental results also show that the proposed IFA have efficiencies of more than 60% throughout the bands of interest. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:523–528, 2014.     

A compact uniplanar antenna for nine‐band LTE/WWAN operation in tablet computers

A compact uniplanar dual wideband antenna for tablet computers is presented. The proposed antenna provides full coverage of LTE700/2300/2500, GSM850/900/1800/1900, UMTS2100, Bluetooth, and 2.4‐GHz WLAN bands with a very small foot print 30 × 10 mm². The antenna has uniplanar structure and is easy to fabricate on single side of 0.8‐mm thick FR4 substrate. This is achieved through three optimized strips: a feeding strip, an inductively coupled inverted L‐shaped strip, and a shorted strip embedded with SMT components. The proposed design supports more than eight operating bands in 3:1 VSWR standard, exhibiting positive gains over all nine bands of operation and 80%–90% radiation efficiency in the higher LTE and WWAN bands. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:496–502, 2016.     

Compact meander T‐shaped monopole antenna for dual‐band WLAN applications

A compact coplanar waveguide‐feed monopole antenna with dual‐band characteristics is proposed in this article. The proposed antenna mainly consists of meander T‐shaped monopole and small ground plane embedded with a pair of L‐shaped couple slots and two pairs of I‐shaped notched slots symmetrically. By elongating the meander T‐shaped arms and carefully selecting the positions and lengths of L‐shaped slot and I‐shaped slot, the antenna excites four resonant frequencies at 2.42, 2.52, 4.75, and 5.54 GHz which are formed into two wide bands to cover all the 2.4/5.2/5.8 GHz wireless local area network (WLAN) operating bands, and is with miniaturization structure. Moreover, the antenna can provide nearly dipole‐like radiation patterns and good gains across the dual operating bands. These results prove that the proposed dual‐band antenna is very suitable for WLAN applications. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013.     

Dual antenna system for metal frame mobile phone applications

A dual antenna system with 77 mm × 10 mm × 7.5 mm for metal frame (MF) LTE/GPS mobile phones is proposed and studied. The antenna proposed in this study comprises two antenna elements (Ant 1 and Ant 2) and a decoupling line. Ant 1 as the main antenna that covers the lower band (698‐960 MHz), the GPS band, and the higher band (1710‐2690 MHz) consisting of a ground branch, a coupled line, and a tuning line. Ant 2 as the auxiliary antenna that covers the higher band consisting of a monopole branch and a match circuit. Ant 1 and Ant 2 form a two‐element MIMO antenna covering the higher band. The advantages of the proposed antenna are that the main antenna (Ant 1) covers the GPS band and all of the 2G/3G/4G bands, and the two‐element MIMO antenna covering the higher band, which consists of Ant 1 and Ant 2 located at the same side of a mobile phone with an MF, is obtained. A prototype is manufactured and tested. For Ant 1, the measured working bands (under ?6 dB condition) are 685 to 965 MHz and 1480 to 2800 MHz, and the LTE700, GSM850, GSM900, GPS, GSM1800, GSM1900, UMTS, LTE2300, and LTE2500 bands are covered. For Ant 2, the measured working band (under ?6 dB condition) is 1640 to 2720 MHz, and the GSM1800, GSM1900, UMTS, LTE2300, and LTE2500 bands are covered. The measured isolations between Ant 1 and Ant 2 are larger than 12 dB at the working bands. The measured efficiencies, envelope correlation coefficients, and mean effective gains are also presented.