Wide Area Network Operation Research Articles

Decoupled compact ultra‐wideband MIMO antennas covering 3300∼6000 MHz for the fifth‐generation mobile and 5GHz‐WLAN operations in the future smartphone

AbstractDecoupled compact UWB multi‐input multi‐output (MIMO) antennas to cover 3300∼6000 MHz in the future smartphone applications are presented. The obtained UWB can cover the fifth‐generation (5G) mobile operation in 3300∼5000 MHz and 5GHz‐wireless wide area network (WLAN) operation in 5150∼5875 MHz to achieve seamless wireless internet access in future wireless communications. The UWB MIMO antennas are based on the coupled‐fed inverted‐F antenna in the planar structure, allowing it easy to implement by printing on the inner surface of the side‐edge frame of the smartphone. Good decoupling between two UWB antennas spaced by 3 mm only and having a small total length of 35 mm (about 0.385λ at 3300 MHz) is obtained without external decoupling structures. The isolation of two nearby UWB antennas is better than 10 dB and the envelope correlation coefficient (ECC) thereof is less than 0.1 in 3300∼6000 MHz. With two UWB antennas as a building block, it is easy to implement at least four MIMO antennas in the future smartphone for at least 4 x 4 MIMO operations in 3300∼6000 MHz for future wireless communications. Details of the proposed UWB MIMO antennas for future smartphone applications are presented.

Single Open-Slot Antenna for LTE/WWAN Smartphone Application

A single open-slot antenna for long term evolution (LTE)/ wireless wide area network (WWAN) operation is proposed for smartphone applications. To achieve dual-band operation, the narrow open-slot is fed by a simple 50- $\Omega$ vertical feedline with two horizontally protruded feeding structures. To further attain good impedance matching for these two operating bands, an L-shaped metallic plate is used. From the measured results, good antenna efficiencies of more than 40% are demonstrated across the LTE/WWAN operation in the 698–960 MHz and 1710–2690 MHz bands.

Bandwidth enhancement of a monopole exciter by using a chip-inductor-loaded shorted strip

ABSTRACTThis paper presents an internal uniplanar monopole exciter fabricated on a 0.8-mm thick FR4 substrate. It can be arranged in the hinge slot of a laptop computer for a long-term evolution/wireless wide area network operation in the 698–960 and 1710–2690 MHz bands. The monopole exciter, which comprises feeding and chip-inductor-loaded shorted strips, occupies a compact area of 25 × 8 mm with a volume of only 0.2 cm3. The exciter antenna not only integrates with the metal covers, but also excites several resonant modes of the hinge slot. The chip-inductor-loaded shorted strip is employed for exciting the hinge slot to enhance lower band bandwidths. The proposed monopole exciter antenna not only serves as an exciter, but also serves as a radiator for generating several of its resonant modes. It can be installed in the hinge slot and has wide operating bands with high radiation efficiency. Over the lower and upper bands, the antenna efficiencies are higher than 56%, which is favorable for practical applications.

IFA-Based Metal-Frame Antenna Without Ground Clearance for the LTE/WWAN Operation in the Metal-Casing Tablet Computer

A metal-frame antenna for the long-term evolution/wireless wide area network (LTE/WWAN) operation in the metal-casing tablet computer is presented. The antenna is formed by using two inverted-F antenna (IFA) structures to provide a low band and a high band to, respectively, cover the LTE/WWAN operation in the 824–960 and 1710–2690 MHz bands. The larger IFA has a longer radiating metal strip for the low band, and the smaller IFA has a shorter radiating metal strip for the high band. The two radiating metal strips are configured to be a portion of the metal frame disposed around the edges of the metal back cover of the tablet computer. The projection of the metal frame lies on the edges of the metal back cover, such that there is no ground clearance between the projection and the metal back cover. Furthermore, the feeding and shorting strips with matching networks therein for the two IFAs are disposed on a small dielectric substrate (feed circuit board), which is separated from the system circuit board and the metal back cover. In this case, there is generally no planar space of the metal back cover and system circuit board occupied, and the antenna can cover the 824–960/1710–2690 MHz bands. Results of the proposed antenna are presented. An extended study is also presented to show that the antenna’s low-band coverage can be widened from 824–960 to 698–960 MHz. The wider bandwidth coverage is obtained when a switchable inductor bank is applied in the larger IFA.

Small‐size adjustable LTE/WWAN coupled‐fed loop antenna for mobile handset applications

ABSTRACTA compact reconfigurable coupled‐fed loop antenna of the mobile handset for multiband long‐term evolution (LTE)/wireless wide area network operation is presented. The antenna volume is 5 × 10 × 30 mm3 only, while the protruded ground has a width of 30 mm for mounting electronic components. The proposed antenna is consisted of a loop strip and a driven strip. Through the driven strip capacitively coupled to the loop strip, the antenna can generate a 0.25‐wavelength loop resonant mode to form the antenna's lower band to cover the GSM850/900 bands (824–960 MHz). The simple driven strip is also an efficient radiator to excite a resonant mode for the antenna's upper band to cover the GSM1800/1900/WCDMA Band1 bands (1710–2170 MHz). Moreover, when the chip inductor connected to the loop strip has been adjusted from 0 to 12 nH, the antenna's lower band can be shifted to lower frequency and cover the LTE Band17 band (704–746 MHz) and the antenna's upper band is not varied. This tunable technique can allow the loop antenna to cover more operating bands without adding the antenna volume. Detailed operating principle and performances of the proposed antenna are discussed in this article. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2687–2691, 2014

Small-Size Stacked Inverted-F Antenna With Two Hybrid Shorting Strips for the LTE/WWAN Tablet Device

The stacked inverted-F antenna with two hybrid shorting strips placed close to the antenna's feeding strip can provide two wide operating bands to cover long-term evolution/wireless wide-area network operation (698-960/1710-2690 MHz) in the tablet device. The antenna's lower and higher bands are, respectively, contributed by the longer and shorter arms of the antenna. The two hybrid shorting strips include an inductive shorting strip (chip-inductor-loaded strip) and a capacitive shorting strip which capacitively couples to the antenna's shorter arm. The longer arm is also coupled through a chip inductor to the feeding strip such that the longer arm has a decreased resonant length for the low-band operation and, on the other hand, has very small effects on the high-band operation, which is mainly contributed by the shorter arm. The feeding strip is also embedded with a chip capacitor such that an internal high-pass matching circuit formed by the inductive shorting strip and the capacitive feeding strip is obtained to greatly widen the antenna's low-band bandwidth, with small effects on the high-band operation. On the other hand, the capacitive shorting strip is added to greatly enhance the bandwidth of the antenna's higher band, with small effects on the low-band operation. Two wide operating bands are hence easily obtained and adjusted. The antenna can also be recessed in a small ground clearance of 10 × 35 mm 2 inside the tablet device such as a tablet computer in this study. Details of the proposed antenna are presented.

Coupled‐fed inverted‐F antenna using an inverted‐F coupling feed for small‐size LTE/WWAN tablet computer antenna

ABSTRACTA coupled‐fed inverted‐F antenna for small‐size dual‐wideband operation in the mobile communication devices, especially the slim tablet computers, for the long term evolution/wireless wide area network (LTE/WWAN) operation, is proposed. The antenna comprises a folded radiating strip and an inverted‐F coupling feed. The former is grounded to the device ground plane and is capacitively excited by the inverted‐F coupling feed. Two wide operating bands to cover the LTE/WWAN operation in the 704∼960 and 1710∼2690 MHz bands are generated for the antenna. In addition, the antenna's metal pattern has a planar structure and occupies a small area of 10 × 40 mm2 on a 0.4‐mm thick FR4 substrate. Operating principle and design considerations of the proposed antenna to generate the dual‐wideband operation are addressed. Experimental results of the fabricated antenna are also presented and discussed. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1296–1302, 2014

Design of dual‐monopole slots antenna integrated with monopole strip for wireless wide area network mobile handset

An internal antenna for penta-band wireless wide area network (WWAN 824–960/1710–2170 MHz) operation in the mobile handset is presented. By integrating two monopole slots with a monopole strip printed on the top portion of the main circuit board, the monopole slots generate their quarter-wavelength slot modes for the antenna's lower band, whereas the monopole strip can contribute quarter-wavelength resonant modes for the antenna's upper band. The monopole strip serves as a feed for the monopole slots and also functions as an efficient radiator. In this case, the antenna can provide two wide operating bands (795–1035/1700–2205 MHz) to cover the penta-band WWAN operation.

A simple penta‐band reconfigurable antenna for mobile device applications

ABSTRACTA simple reconfigurable antenna for mobile device applications is proposed in this letter. The proposed structure uses a conventional planar inverted‐F antenna as its basic geometry and a single PIN diode embedded in the middle of the shorting line. The proposed antenna has two resonances (f1 and f2). These resonances are easily controlled by electrically controlling the on/off state of the PIN diode. The measured results show that the basic resonance f1 covers the GSM850 (824–894 MHz) and GSM900 (880–960 MHz) bands in the lower band, and the harmonic resonance f2 includes digital communication system (1710–1880 MHz), personal communication system (1850–1990 MHz), and universal mobile telecommunications system (1920–2710 MHz) bands in the higher band. Therefore, the proposed antenna achieves penta‐band wireless wide area network operation. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:769–774, 2014

Internal multiple‐input, multiple‐output antenna arrays for wireless wide area network and wireless local area network operation in seamless full metal cover laptops

A concept for multiple-input, multiple-output antenna arrays, integrated in an ultra-thin full metal cover laptop computer, is proposed. The antennas are for octa-band wireless wide area network (WWAN) and triple-band wireless local area network (WLAN) operation. The proposed solution makes use of the gap between the metallic display lid and keyboard chassis to form notch and slot antenna arrays, thereby removing the need for additional protrusions or openings. Simulated as well as measured performance is presented. The notch antenna array for WWAN exhibits wide impedance bandwidth, with more than 24 dB isolation from 690 MHz to 3 GHz, and a total efficiency better than −2.5 dB. The slot antenna array for WLAN shows more than 12 dB isolation and a total efficiency of more than −3 dB. Both arrays exhibit a very low envelope correlation coefficient of less than 0.1 within their respective frequency bands.

Simple Printed WWAN Monopole Slot Antenna with Parasitic Shorted Strips for Slim Mobile Phone Application

ABSTRACTIn this article, a simple printed monopole slot antenna with two parasitic shorted strips (a longer parasitic shorted strip and a shorter parasitic shorted strip) for penta‐band wireless wide area network operation in the slim mobile phone is presented. The monopole slot has a length of 40 mm only and is disposed near the bottom edge of the system ground plane of the mobile phone with a small distance of 6.5 mm. By adding longer parasitic shorted strip connected to the bottom corner edge of the system ground plane, good excitation of the monopole slot antenna at its fundamental (quarter‐wavelength) mode and chassis dipole‐type mode of the system ground plane can be obtained. The shorter parasitic shorted strip contributes additional resonant mode to the antenna. The excited resonant modes form two wide operating bands to cover the GSM850/900 operation (824–960 MHz) and GSM1800/1900/WCDMA Band I operation (1710–2170 MHz), respectively. Details of the proposed antenna are presented. The specific absorption rate results for the antenna with the presence of the head and hand phantoms are also studied. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2835–2841, 2013

Printed dual‐feed triangular patch antenna disposed in a small notch in the handheld device system ground plane for LTE/WWAN operation

ABSTRACTA printed triangular patch antenna disposed in a small notch at one corner of the system ground plane of the handheld communication device such as the smartphone, tablet computer, and phone tablet for long term evolution/wireless wide area network (LTE/WWAN) operation is presented. The small notch has a size of 10 × 20 mm2 only, and two tips of the triangular patch disposed therein are in close proximity to two adjacent perpendicular edges of the notch. The two tips are the antenna's two feeds for achieving LTE/WWAN operation. Each tip can be connected to an ON/OFF switch (e.g., a PIN diode) such that the antenna can be controlled to be fed at either the first or the second tip. When fed at the first tip, the antenna will operate in a high‐frequency band (1710–2690 MHz) to cover the GSM1800/1900/UMTS/LTE2300/2500 operation. When fed at the second tip and aided by a matching circuit, the antenna will operate at a low‐frequency band (824–960 MHz) to cover the GSM850/900 operation. Design considerations of the proposed antenna are described. Parametric studies and experimental results of the antenna are presented and discussed. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2767–2773, 2013

A Dualband Coupled-Fed Lte/Wwan Planar Antenna for Mobile Devices

A coupled-fed antenna that combines the long term evolution operation with the wireless wide area network operation is proposed. The antenna is mainly composed of a T-shaped radiator linked to the ground plane via a narrow meandered line. Good impedance matching throughout all bands of interest is achieved by embedding a C-shaped coupling structure into the narrow meandered line, followed by protruding a small stub at the right bottom corner (vertical structure) of the T-shaped radiator. Furthermore, by reconstructing the coupled-fed structure as a halved-tapered fed design, two wide operating bands that operate between 680 and 1380 MHz (68%), and 1550 and 2830 MHz (58.4%) are achieved. The process of designing the proposed antenna is explicitly shown, and parametric studies were carried out by simulation. Typical experimental measurements were also conducted and compared to the simulated results. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1851–1856, 2013

Decoupled WWAN/LTE antennas with an isolation ring strip embedded therebetween for smartphone application

AbstractAn integrated antenna array comprising two decoupled multiband WWAN/LTE antennas having an isolation ring strip embedded therebetween and all disposed on a same FR4 substrate of small size 10 × 70 mm2 is presented. The two decoupled antennas cover the 824–960/1710–2690 MHz bands for the GSM850/900 and GSM1800/1900/UMTS/LTE2300/2500 operations and are promising to be mounted at the bottom edge of a smartphone for dual wireless wide area network (WWAN) operation for dual‐talk function or for long term evolution (LTE) multiple‐input multiple‐output operation. The measured transmission coefficient S21 between the two antennas is less than −15 dB over both the 824–960 and 1710–2690 MHz bands, and the envelop correlation coefficient is less than about 0.03 over both bands. Port‐decoupling of the two antennas is obtained because the excited surface currents on the system ground plane of the smartphone between the two antennas are decreased owing to the isolation ring strip attracting some of the same. In addition to good isolation obtained, the antenna efficiencies are better than about 40 and 50% over the lower and upper bands, respectively. Details of the decoupled WWAN/LTE antennas are described. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1470–1476, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27654

Small‐size printed coupled‐fed antenna for eight‐band LTE/GSM/UMTS wireless wide area network operation in an internal mobile handset

A simple small-size printed antenna for eight-band long-term evolution (LTE)/GSM/UMTS wireless wide area network operation in an internal mobile handset application is proposed. Occupying a compact size of 15 × 40 mm2 on the ungrounded region of the system circuit board and a low profile of 4 mm, the presented antenna is a coupled-fed configuration. With the longer branch of the feeding strip, a λ/4 resonant mode at around 2.7 GHz can be obtained to cover the desired LTE2500 operation. A fundamental λ/4 resonant mode over the desired lower band of LTE700/GSM850/900 can also be generated at 750 MHz by the long meandered coupling strip (length of about 113 mm). Moreover, two additional higher-order resonant modes at around 1.75 and 2.25 GHz can also be obtained by the coupling strip. By including a chip inductor L at the feeding point, the impedance matching over the lower and upper bands can be improved in order to achieve the two wide operating bands of 698–960 and 1710–2690 MHz. With the following properties of small size, ease of fabrication and good radiation characteristics, the proposed antenna is a good candidate for the fourth LTE mobile phone applications.

Small-Size Triple-Wideband LTE/WWAN Tablet Device Antenna

A small-size tablet device antenna with three wide operating bands to cover the Long Term Evolution/Wireless Wide Area Network (LTE/WWAN) operation in the 698 ~ 960-, 1710 ~ 2690-, and 3400 ~ 3800-MHz bands is presented. The antenna has a planar structure and is easy to fabricate on one surface of a thin FR4 substrate of size 10×45×0.8 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . The antenna is formed by adding a first branch (branch 1, an inductively coupled strip) and a second branch (branch 2, a simple branch strip) to a coupled-fed shorted strip antenna (main portion), and the two branches are configured with the main portion to achieve a compact antenna structure. The three widebands are easy to adjust and can cover the LTE/WWAN operation, which includes the most commonly commercial LTE bands and WWAN bands (698 ~ 960 and 1710 ~ 2690 MHz) and the LTE 3.5-GHz band (3400 ~ 3800 MHz).

WWAN printed monopole slot antenna with a parallel-resonant slit for tablet computer application

The use of a parallel-resonant (PR) slit for dual-band bandwidth enhancement of a small-size printed monopole slot antenna to achieve the wireless wide area network operation in the tablet computer is demonstrated. The antenna is easy to fabricate by printing on a thin FR4 substrate of size 10 × 45 mm2. The PR slit, mainly configured as a spiral shape to occupy a small area of about 6.5 × 6.5 mm2 on the FR4 substrate, generates two parallel resonances at about 1.2 and 2.5 GHz to, respectively, result in dual-resonance excitation of the quarter-wavelength and half-wavelength modes of the monopole slot at about 0.9 and 1.9 GHz. In this case, two wide operating bands are obtained to, respectively, cover the 824–960 and 1710–2170 MHz bands. That is, with the dual-band bandwidth enhancement contributed by the PR slit, the proposed antenna can cover the GSM850/900/1800/1900/UMTS bands with a small planar size. Details of the proposed antenna are described in the article. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:40–45, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27273

Integration of monopole slot and monopole strip for internal WWAN handset antenna

AbstractA novel internal handset antenna formed by a monopole slot and a monopole strip for the wireless wide area network (WWAN) operation in the 824–960 and 1710–2170 MHz bands is presented. The monopole strip is disposed in the monopole slot, and both are embedded in the system ground plane of the handset with a small board space of 9 × 40 mm2 at about the bottom edge of the circuit board. The monopole strip serves as a feed for the monopole slot and also functions as an efficient radiator. In the proposed design, the monopole slot generates a quarter‐wavelength slot mode in the antenna's lower band, while the monopole strip contributes its quarter‐wavelength mode in the antenna's upper band. By including a vertical strip that can be enclosed inside the handset casing or be a part of the bezel surrounding, the periphery of the handset casing and connected to the bottom edge of the system ground plane, the impedance matching of the excited slot mode can be greatly improved. In this case, the proposed antenna can provide two wide operating bands with good impedance matching to cover the pentaband WWAN operation. Detailed operating principle of the integrated monopole slot and monopole strip for the internal WWAN handset antenna is described. The proposed antenna is also fabricated and obtained results are presented and discussed. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1718–1723, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26870

Small‐size WWAN monopole slot antenna with dual‐band band‐stop matching circuit for tablet computer application

AbstractA monopole slot antenna printed on a small‐size FR4 substrate of 40 × 10 mm2 to provide two wide operating bands of 824–960 and 1710–2170 MHz for the wireless wide area network operation in the tablet computer is presented. The monopole slot is folded to achieve a compact configuration and is fed by a microstrip feedline loaded with a dual‐band band‐stop matching circuit on the same FR4 substrate. The band‐stop matching circuit can generate two separate parallel resonances at about 1050 and 2250 MHz, which respectively leads to additional resonance occurred nearby the resonant frequencies of the quarter‐wavelength slot mode at about 850 MHz and higher‐order slot mode at about 1900 MHz, thereby resulting in dual‐resonance excitation of the two excited slot modes to respectively cover the GSM850/900 and GSM1800/1900/UMTS operation. The bandwidth‐enhancement technique of using a dual‐band band‐stop matching circuit is reported for the first time in published articles, and its detailed operating principle is described in this study. Performances of the proposed antenna are also discussed. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:875–879, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26723

Internal coupled‐fed loop antenna integrated with notched ground plane for wireless wide area network operation in the mobile handset

AbstractAn internal wireless wide area network (824–960/1710–2170 MHz) antenna suitable to be disposed at a notched region (size 10 × 40 mm2) of the system ground plane of the handset to achieve compact integration therein is presented.The notched system ground plane, compared to the traditional rectangular system ground plane at which the internal antenna is generally disposed at the entire top or bottom edge of the ground plane, can lead to more compact layout design of the internal antenna and associated electronic elements in the handset. The proposed antenna has a simple structure occupying a small volume of 10 × 40 × 5 mm3 and comprising a monopole feed and a coupled strip. The latter is coupled‐fed by the monopole feed to provide a 0.25‐wavelength loop path, which generates a 0.25‐wavelength loop mode at about 850 MHz and a higher‐order loop mode at about 1.7 GHz. The monopole feed also contributes a 0.25‐wavelength mode at about 2.1 GHz to combine with the higher‐order loop mode to form the antenna's upper band. The bandwidth enhancement of the 0.25‐wavelength loop mode is obtained by adding an external bandstop circuit, which makes the desired antenna's lower band achieved. The antenna also meets the specific absorption rate and hearing‐aid compatibility requirements for practical applications. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:553–555, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26620