Loop Strip Research Articles

A Compact Dual-Band ACS-Fed Frequency Independent Hook Loop Antenna for WLAN Applications

ABSTRACT Presented in this paper is a simple, small-sized, and hook-shaped monopole antenna fed by an Asymmetric Coplanar Strip (ACS) for different dual-band operations. The antenna operates at 3.5 and 5.2 GHz; hence, serving WiMAX and WLAN applications. Dual resonances were attained by integrating a quarter-wavelength strip with a C-shaped half-wavelength loop strip. The proposed antenna footprint is 20 × 7.9 mm2. Based on the achieved outcomes and the antenna compactness, it can be highly nominated for use in 3.5/5 GHz wireless communications applications and wireless gadgets.

Mutual Coupling Reduction in Closely Spaced MIMO Dielectric Resonator Antenna in H-Plane Using Closed Metallic Loop

In this study, the mutual coupling in multiple-input-multiple-output (MIMO) dielectric resonator antenna (DRA) is reduced by employing closed metallic loops. The loops are wrapped around the adjacent edges of the dielectric resonators (DR) where magnetic coupling is significant. The proposed method employs only the conductive metallic strips for mutual coupling reduction and this makes the entire design very simple and compact. The impedance bandwidth varies from 4.73 to 5.1 GHz, covering the Sub–6 GHz 5G band. The realized MIMO DRA has an isolation of 28 dB at the resonant frequency with a measured peak gain at each port of 3.5 dBi and a peak radiation efficiency of 93%. The obtained measured results yield a low correlation coefficient (<0.05) mostly at the entire band that contribute to diversity gain (> 9.8 dB) to increase the capacity of communication system, is reported in this paper. The proposed antenna was fabricated and the closed loop strip is wrapped around using in house facility. Furthermore, some issues related to the fabrications tolerance have been investigated to justify the difference between some simulated and measured results.

Novel Frequency-Selective Rasorber with Ultrawide Absorption Bandwidth Covering Both the X- and Ku-Bands

A novel dual-polarized transmissive/absorptive frequency-selective rasorber (FSR) with an ultrawide absorption spectrum covering both the X- and Ku-bands is proposed in this paper. The FSR is constructed from a bottom lossless transmission layer and a top lossy absorption layer, in which a resistor-loaded incurved square loop strip line structure is utilized to obtain an ultrawide absorption band. To quantitatively analyze its operation principle, an accurate equivalent circuit model of the proposed FSR was developed. A 2D prototype was designed, assembled, fabricated, and measured. The FSR exhibits an absorption band that ranges from 8.1 to 19.1 GHz (81%) under normal incidence, whereas the passband insertion loss at 4.5 GHz is less than 0.45 dB. The total thickness of the FSR is only 5.1 mm, which keeps low profile characteristics. The simulation agrees well with the measured results.

Wideband dual‐band dual‐polarised antenna with less layer radiating patch

A wideband dual-band dual-polarised patch antenna is proposed here. It consists of a ground that has a cross slot and a rectangle hole, a feeding structure that consists of two π-shape strips, and a radiating patch that consists of a square loop strip and a small square patch with a cross slot. Two feeding ports are used to generate two orthogonal polarisations. A prototype has been fabricated and measured. The measured -10 dB impedance operating bands of the two ports can cover the bands of 3.59-4.21 GHz and 5.42-6.34 GHz, the relative bandwidth are 15.9% and 15.6%. The measured isolations between the two ports are more than 20 and 15 dB at the lower and higher bands, respectively. The antenna has a good radiation performance at the lower and higher bands.

Zip Unfolding of the Regular Tetrahedron to a Loop Strip

Zip Unfolding of the Regular Tetrahedron to a Loop Strip

A compact tri-band antenna at GPS and WLAN a/b/g for tablet computer with full metal housing

A very small antenna for full metal housing (FMH) tablet that can provide GPS and WLAN 2.4/5.2/5.8 GHz operations is presented. This miniaturized antenna is formed by a loop strip of about 41 mm with its end terminal connected to the ground via an inductor, and its front section capacitively coupled to a feed strip. Except for the antenna self-resonant modes (loop modes); two cavity modes are also involved to realize multi-bands operation, which is a novel technique for antenna design in FMH devices. Here, the three loop modes are at 1.575 GHz, 5.2 GHz, 6 GHz, and the two cavity modes are at 2.45 GHz and 5.4 GHz. The measured efficiencies at 1.575, 2.45, and 5.5 GHz were 36%, 79%, and 78%, respectively. Because the loop strip is only 0.18λ and in meander line shape at GPS frequency, the planar dimension of proposed antenna can be reduced to 10 × 8 mm2. Therefore, the proposed antenna has very competitive size for applications in this operation environment. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:739–746, 2016.

Planar super‐wideband loop antenna with asymmetric coplanar strip feed

A planar super-wideband (SWB) antenna fed by an asymmetric coplanar strip is proposed, fabricated, and tested. The antenna consists of a hexagonal loop strip in which a signal strip is prolonged, curved, and shorted to a ground plane to facilitate SWB characteristics. In addition, by adding a boomerang-shaped strip to the ground plane, the effective electrical length is increased, thereby decreasing the lowest operating frequency. The simulated results show that the proposed antenna exhibits a −10 dB reflection bandwidth from 1.18 to 49.22 GHz corresponding to a ratio bandwidth of 41.7:1. The measured results of the fabricated antenna are also represented and compared with the simulated results. The antenna gain changes from 2.05 to 10.62 dBi within the measured frequency range.

Study and Design of Broadband Bow-tie Slot Antenna Fed With Asymmetric CPW

In this communication, a new style of broadband bow-tie slot antenna with an improved gain is presented. It is fed by an asymmetric coplanar waveguide (ACPW) with different slot lengths. By adjusting the length of one ACPW slot, the impedance characteristic of the antenna is greatly improved so that the bandwidth is broadened. Meanwhile, to improve the gain at low frequency band, a loop strip is added in the bow-tie slot. The simulated and measured results show that the proposed antenna can operate from 2.76 GHz to 8.1 GHz and the relative bandwidth is 100.4%. Furthermore, the flatter gain within the operating frequency band is obtained and the maximum gain at beam peak reaches 5.53 dBi.

COMPACT PRINTED DIVERSITY ANTENNA FOR LTE700/GSM1700/1800/UMTS/WI-FI/BLUETOOTH/LTE2300/2500 APPLICATIONS FOR SLIM MOBILE HANDSETS

A planar, printed multiple-input multiple-output (MIMO) antenna for slim mobile handset is presented. The dual-antenna system, comprises two symmetric antenna elements, is printed on a printed circuit board (PCB) of mobile phone. Each antenna element consists of coupled-fed loop antenna. The loop antenna is formed by a quarter wavelength (at 762MHz) meandered loop strip with end terminal short-circuited to the ground plane. A T-shaped protruded ground is deliberately designed to enhance the impedance matching and decoupled the two closely deposed antenna elements (distance between antenna elements are 0.03λ at 762MHz). The integrity of the T-shaped decoupling structure and coupled-fed loop antenna array covers LTE700 (0.747GHz–0.787 GHz) and WWAN (1.7GHz– 3.04GHz) based on −6 dB reflection coefficient and achieves isolation between elements well below −10 dB over all the operating bands. The application platform is LTE700, GSM1700, GMS1800, UMTS, Wi-Fi, Bluetooth, LTE2300, and LTE2500 bands for the 2G/3G/4G mobile terminals. The effect of user proximity by considering the actual mobile environment is also studied in the form of total radiated power (TRP), specific absorption rate (SAR), diversity performances, and radiation performances. Finally, a prototype is fabricated and tested with network analyser. The measured results are found in good agreement with simulated ones.

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

Multicriteria synthesis of combined stochastic robust system by co-regulation thickness, tension and loop strip finishing group broadband hot rolling mill

Multicriteria synthesis of combined stochastic robust system by co-regulation thickness, tension and loop strip finishing group broadband hot rolling mill

Design of multi-band CPW-fed antenna for triple-frequency operation

Presented is a coplanar waveguide fed antenna for multi-band operation covering the digital video broadcasting signal reception in the UHF band, mobile communications in the GSM band, and the 2.4 GHz 802.11g/n band. The size of the designed antenna is 114×60 mm and it is printed on an FR4 substrate of thickness 0.8 mm with dielectric constant 4.4. It has an inner U-shaped strip enclosed by an outer loop strip and the outer loop strip is designed to obtain a wide operating bandwidth. Experimental results show that the proposed antenna exhibits a good impedance matching over a wide frequency range of 470 to 960 MHz, 1450 to 1880 MHz, and 2.4 to 2.6 GHz.

Formation of horizontally polarized radiation in a cylindrical microstrip antenna

We consider the problem of excitation of cylindrical microstrip antennas with complex-shaped radiators, which are capable of producing radiation mainly with horizontal polarization. The problem is solved by the method of moments in the spectral domain by using the piecewise-specified basic functions. The radiating systems under consideration are a rectangular-cylindrical radiator with a matching coplanar transition and two pairs of coupled loop strip radiators with slots located in the azimuthal plane. The radiators are excited by a cylindrical microstrip line, and the line, with a delta generator. Coupling of the radiating system and the microstrip line is achieved. The possibility to produce the horizontally polarized radiation, which is isotropic in the azimuthal plane, is demonstrated.

Printed Internal Pentaband WWAN Antenna Using Chip-Inductor-Loaded Shorting Strip for Mobile Phone Application

A compact size on-board printed antenna using capacitive coupled-fed excitation to generate multiple resonant modes for penta-band WWAN operation (GSM850/900/GSM1800/1900/UMTS2100) is presented in this paper. The proposed antenna occupies only a small footprint of 15 × 25 mm2on one corner of the circuit board and a protruded ground of 10 × 15 mm2is displaced with close proximity to the antenna portion. The proposed antenna has a very simple structure which is composed of two separate strips: a loop strip with an inserted chip inductor and an L-shaped feeding strip. The loop strip is shorted to the ground and generates a resonant mode at 890 MHz to cover the GSM850/900 band (824–960 MHz) while the feeding strip contributes to the GSM1800/1900/UMTS210 band (1710–2170 MHz) operation. With such a small size, the proposed antenna can achieve compact integration on the circuit board of the mobile phone, thus the proposed scheme is quite suitable for the slim mobile phone application. Good agreements between simulations and measurements are obtained. Details of proposed antenna are presented and some key parameters are studied.

Wwan/lte printed loop tablet computer antenna and its body sar analysis

AbstractA WWAN/LTE printed loop antenna for tablet computer application is presented.The printed loop antenna is a half‐wavelength loop strip coupled‐fed by a patch monopole, which performs not only as a coupling feed but also as an efficient radiator for the antenna. By embedding a printed distributed inductor in the loop strip, dual‐resonance excitation of the half‐wavelength mode of the coupled‐fed loop antenna is obtained, which forms the antenna's lower band at about 800 MHz to cover the LTE700/GSM850/900 operation (704–960 MHz). The antenna's upper band is formed by both the resonant modes contributed by the patch monopole and the higher order resonant modes contributed by the loop strip. The upper band shows a large bandwidth (>1 GHz) to cover the GSM1800/1900/UMTS/LTE2300/2500 operation (1710–2690 MHz). Further, with a planar and compact structure (12 × 75 mm2), the antenna is suitable to be disposed in the limited space inside the tablet computer and meets the body specific absorption rate (SAR) requirement (<1.6 W/kg for 1‐g body tissue) for practical applications. Details of the proposed antenna and its body SAR results are presented. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2912–2919, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26377

On-Board Printed Coupled-Fed Loop Antenna in Close Proximity to the Surrounding Ground Plane for Penta-Band WWAN Mobile Phone

A small-size coupled-fed loop antenna suitable to be printed on the system circuit board of the mobile phone for penta-band WWAN operation (824-960/1710-2170 MHz) is presented. The loop antenna requires only a small footprint of 15 x 25 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> on the circuit board, and it can also be in close proximity to the surrounding ground plane printed on the circuit board. That is, very small or no isolation distance is required between the antenna's radiating portion and the nearby ground plane. This can lead to compact integration of the internal on-board printed antenna on the circuit board of the mobile phone, especially the slim mobile phone. The loop antenna also shows a simple structure; it is formed by a loop strip of about 87 mm with its end terminal short-circuited to the ground plane and its front section capacitively coupled to a feeding strip which is also an efficient radiator to contribute a resonant mode for the antenna's upper band to cover the GSM1800/1900/UMTS bands (1710-2170 MHz). Through the coupling excitation, the antenna can also generate a 0.25-wavelength loop resonant mode to form the antenna's lower band to cover the GSM850/900 bands (824-960 MHz). Details of the proposed antenna are presented. The SAR results for the antenna with the presence of the head and hand phantoms are also studied.

Quarter-Wavelength Printed Loop Antenna With an Internal Printed Matching Circuit for GSM/ DCS/PCS/UMTS Operation in the Mobile Phone

A small-size printed loop antenna with an internal printed matching circuit capable of GSM/DCS/PCS/UMTS operation in the mobile phone is proposed. The antenna comprises an 85-mm long folded loop strip and an internal printed matching circuit encircled therein and formed by a coupling strip and an inductive strip. The loop strip is excited by the coupling strip to generate a 0.25 lambda resonant mode at about 900 MHz for GSM operation. For the inductive strip, it effectively causes a wideband higher order mode at about 1900 MHz for DCS/PCS/UMTS operation. Further, the antenna shows a uniplanar structure and requires a very small printed area of 170 mm2 on the system circuit board of the mobile phone, making it easy to fabricate at low cost. Details of the proposed antenna and its radiation performances including the SAR (specific absorption rate) results are studied.

Small‐size wireless wide area network loop chip antenna for clamshell mobile phone with hearing‐aid compatibility

AbstractA loop chip antenna with an FR4 chip base suitable for clamshell mobile phone application to achieve wireless wide area network operation and hearing‐aid compatibility (HAC) is presented. The loop chip antenna is formed by a loop strip excited by a capacitively coupled feed, all printed on the surfaces of the FR4 chip base to achieve a small size of 1.35 cm3 only. Two resonant loop paths are provided by the antenna and each loop path can generate its 0.5λ and 1.0λ resonant modes with good impedance matching. The excited loop resonant modes are formed into two wide operating bands for the antenna to cover GSM850/900 and GSM1800/1900/UMTS operations for both the open (talk) and closed (idle) states of the clamshell mobile phone. Furthermore, the loop antenna also excites small surface currents on the two ground planes of the clamshell mobile phone. In this case, weak near‐field EM fields in the vicinity of the mobile phone can be generated. Results show that the strengths of the near‐field E‐field and H‐field fall in the M3 or M4 Category, making the clamshell mobile phone with the proposed antenna to be an HAC communication device. The obtained specific absorption rate values in 1‐g and 10‐g head tissues also meet the limit of 1.6 and 2.0 W/kg, respectively. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2327–2335, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24665

Compact Multiband Folded Loop Chip Antenna for Small-Size Mobile Phone

A multiband folded loop chip antenna with a very small volume of 1 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> (40 times 5times 5 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> ) is presented. The antenna has a simple metal pattern comprising a folded loop strip and a tuning pad, and is especially suited for application in small-size mobile phones (groundplane length 60 mm only) for multiband operation. The metal pattern is attached on the surfaces of a foam base, and the first three resonant loop modes (0.5-, 1.0-, and 1.5-wavelength modes) of the antenna can be excited with good impedance matching by simply adjusting proper dimensions of the tuning pad and its location along the folded loop strip. The excited 0.5-wavelength mode forms as the antenna's lower band at about 900 MHz for GSM operation, while the 1.0- and 1.5-wavelength modes are formed into a wide operating band at about 1900 MHz for the antenna's upper band to cover DCS/PCS/UMTS operation. Design considerations of the proposed folded loop chip antenna are described, and effects of the tuning pad on controlling the performances of the antenna are shown.

Seven‐band surface‐mount loop antenna with a capacitively coupled feed for mobile phone application

AbstractA surface‐mount loop antenna with a capacitively coupled feed capable of seven‐band operation in the mobile phone is presented. The capacitively coupled feed successfully excites the 0.5‐, 1.0‐, and 1.5‐wavelength modes of the loop antenna. Further, the presence of the capacitively coupled feed leads to a new loop path, whose length is slightly less than that of the original loop strip. The 0.5‐, 1.0‐, and 1.5‐wavelength modes of the new loop path are also excited with good impedance matching. The two 0.5‐wavelength modes of the new loop path and original loop strip form a wide bandwidth of 310 MHz for the antenna's lower band to cover GSM850/900 operation. The other modes of the two loops form a very wide bandwidth of larger than 1 GHz for the antenna's upper band to cover GSM1800/1900/UMTS/WLAN/WiMAX operation. With seven‐band operation achieved, the proposed loop antenna only occupies a small volume of 60 × 10 × 3 mm3 (1.8 cm3), and owing to its thin thickness of 3 mm only, and the antenna is very promising for thin mobile phone applications. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 81–88, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23955