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Abstract: A MIMO antenna system based on two dual‐band loop‐slot combination antennas for Wireless Local Area Network (WLAN) applications is proposed. The decoupling element for enhancing the port isolation is based on the neutralization line technique. The bandwidth of operation of the proposed antenna covers both the WLAN 2.4 GHz (2.4–2.484 GHz) and 5 GHz (5.15–5.85 GHz) frequency bands using a −10 dB definition. The isolation between the two closed placed antennas is improved to −16 and −23 dB in the WLAN 2.4 and 5 GHz bands, respectively. The size of the proposed antenna is only 60 × 7.5 × 4.5 mm3 with a metal bottom cover underneath and an LCD panel nearby. Good radiation performance, as quantified by the antenna gain and antenna efficiency, is achieved. [ABSTRACT FROM AUTHOR]

ABSTRACT The combination of matching circuit and strip provides a new approach to realize wide bandwidth of the antenna. We presented a coupled-fed antenna with matching circuit for the LTE/WWAN operation in the tablet computer. The total size of the antenna is of 40 × 10 mm2. Furthermore, the matching circuit of a chip capacitor and chip inductor does not increase the antenna's occupied volume. Details of the proposed antenna and its operating principle are presented and discussed. The excited resonant modes of the proposed antenna cover the desired lower LTE/WWAN band operation (698-960 MHz) and the higher band operation (1710-2690 MHz). Good radiation characteristics of the proposed antenna are also obtained. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1002-1006, 2016 [ABSTRACT FROM AUTHOR]

ABSTRACT A hybrid loop/monopole antenna capable of covering the LTE operation in the 698-960/1710-2690 MHz band and the GPS operation at 1575 MHz for the tablet computer application is presented. With the obtained LTE/GPS operation, the antenna requires a small size of 8 × 40 × 3 mm3 only. The antenna is operated as a coupled-fed loop antenna for the LTE operation and as a coupled-fed monopole antenna for the GPS operation. The two antenna structures share the same radiation strip, except that the loop antenna with the end terminal thereof short-circuited to the device ground plane of the tablet computer and the monopole antenna with the end terminal thereof open-ended. The two antenna structures are configured into one antenna structure using a passive bandstop circuit connected between the end terminal of the antenna's radiation strip and the device ground plane. The bandstop circuit exhibits a very high impedance in the GPS band and a very low impedance in the LTE band, thereby making the antenna operated as a loop antenna for the LTE operation (698-960/1710-2690 MHz) and a monopole antenna at 1575 MHz for the GPS operation. Details of the proposed hybrid loop/monopole antenna are described. Operating principle of the antenna is addressed, and experimental results of the fabricated antenna are presented and discussed. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:630-635, 2016 [ABSTRACT FROM AUTHOR]

ABSTRACT In this study, a compact dual-band antenna for wireless universal serial bus dongle applications is proposed. The proposed structure consists of a conventional folded monopole antenna (driven element) and a strip pattern that extends from the ground (GND) plane (shorten parasitic element). The proposed antenna exhibits triple-resonance (f1, f2, and f3). The first two resonance frequencies (f1 and f2) are generated by adding the shorted parasitic element. The third resonance frequency (f3) is generated by the folded monopole antenna. The first resonance frequency (f1) covers 2.4-GHz wireless local area network (WLAN) service, whereas the second and third resonance frequencies (f2 and f3) cover 5.2/5.8-GHz WLAN service. Thus, dual-band operation for 2.4/5.2/5.8-GHz WLAN service can be easily performed. The antenna occupies a small area of 7 × 20 mm2. It can be easily connected to the edge of the system GND plane or the supporting metal frame of a laptop computer. Details of the proposed antenna are presented and studied. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:2207-2213, 2015 [ABSTRACT FROM AUTHOR]

ABSTRACT In this article, a compact diplexer is proposed using the U-shaped slotline resonator (U-SR) and dual-mode slotline resonator (DM-SR) for wideband and WLAN applications. The filter using the U-SR has three transmission poles in the passband and two transmission zeros near the passband edges. The wide upper-stopband can be realized for the second mode of the U-SR is well suppressed. The DM-SR has two resonant frequencies (odd- and even-modes) in the desired passband. And the odd-mode resonant frequency can be flexibly controlled by the slotline stub, whereas the even-mode one is fixed. Due to the main path signal counteraction and source-load coupling, the filter using the DM-SR possesses two transmission zeros in the upper-stopband. The mutual loading effect of two filters can generate new transmission zeros, which are mainly applied to improve the isolation. Compact size can be obtained without extra matching network. A diplexer prototype is designed, and good agreement can be obtained between measured and simulated results. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2480-2484, 2014 [ABSTRACT FROM AUTHOR]

ABSTRACT A novel multiband loaded trapezoidal ring fractal antenna (TRFA) is proposed for wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications. The self-similarity property is applied to the trapezoidal structure and the fractal geometry is achieved by consecutive iterations. The proposed antenna has a compact size of 30 × 30 × 1.6 mm3. The antenna is fabricated and tested. The fourth iteration of the proposed TRFA covers the 2.4/5.2/5.8 GHz WLAN bands and 2.5/3.5/5.5 GHz WiMAX bands with uniform radiation characteristics and an average gain of 2.20 dBi. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2545-2548, 2014 [ABSTRACT FROM AUTHOR]

ABSTRACT A 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 [ABSTRACT FROM AUTHOR]

ABSTRACT A novel microstrip-line fed beak-shaped monopole-like slot UWB antenna is proposed for enhanced ultrawideband, bluetooth, GPS, and GSM applications. In which, a beak-shaped radiating patch is fed by a microstrip-line and a square ground plane is defected by etching a hexagonal slot. Two triangular slots in the beak-shaped radiator and hexagonal-shaped defect in the ground plane are used to obtain GPS (1520-1590 MHz), GSM (1770-1840 MHz), and bluetooth (2385-2490 MHz). Furthermore, the bandwidth of an antenna is increased by etching a triangular slot at the junction of patch and feeding line. The antenna is fabricated on 1.6 mm thick commercial available FR4 material. The antenna offers an enhanced bandwidth of 24.26 GHz from 0.24 to 24.5 GHz with the voltage standing wave ratio <2. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2624-2628, 2014 [ABSTRACT FROM AUTHOR]

ABSTRACT In this manuscript, a new design of microstrip-fed monopole antenna with meander-line strips for wireless local area network (WLAN) and world-wide interoperability microwave access (WiMAX) systems is proposed. The operating frequencies of the proposed antenna are 2.4/3.5/5.5 GHz, which covers the WLAN and WiMAX bands. The measured results of the proposed antenna show that the impedance bandwidths are from 2.01 to 2.67 GHz, 3.25 to 3.75 GHz, and 5 to 6 GHz. The presented antenna has a small size of 12 × 18 mm2. Various configurations of array of this antenna for multiple input-multiple output (MIMO) application are also studied. It shows that the features of low profile, good return loss, and small mutual coupling are promising for MIMO applications. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2667-2671, 2014 [ABSTRACT FROM AUTHOR]

A compact multiband antenna with composite right- and left-handed transmission line (CRLH-TL) zeroth-order resonator for wireless universal serial bus dongle applications is proposed in this article. The proposed antenna occupying a small volume of 12 × 28 × 5.8 mm3 comprises a folded monopole which can generate two resonant modes to cover the GSM850/900 (820-960 MHz) and the LTE2500 operation (2500-2690 MHz) and a CRLH-TL ZOR structure which is capacitively excited by the folded monopole to generate zeroth-order resonant mode to cover LTE700 (746-787 MHz). The proposed antenna offers nearly omnidirectional radiation patterns, the measured peak gain are obtained from 0.8 to 3.4 dBi, and measured antenna efficiency varies from about 40-56% in the whole operation band. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1133-1138, 2014 [ABSTRACT FROM AUTHOR]

ABSTRACT In this article, a miniature dual-mode dual-band bandpass filter (BPF) based on novel complementary center-stub-loaded stepped-impedance resonators has been presented. By loading an open stub at the center of stepped-impedance resonator, the center frequency of the fundamental even-mode could be independently controlled, whereas that of the fundamental odd-mode is fixed. A dual-mode dual-band BPF using complementary configuration is implemented with three transmission zeros. To validate the design and analysis, a prototype filter has been designed and fabricated with its two bands located at 2.4/5.2 GHz for WLAN. The measured performances show good agreements with those of the coupling matrix analysis and electromagnetic simulation. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1235-1238, 2014 [ABSTRACT FROM AUTHOR]

ABSTRACT A two-patch-planar inverted-F antenna (PIFA) system well suited to functioning inside the tablet computer with a complete, metal back cover for 2.4-GHz wireless local area network operation is proposed. The antenna was constructed by stamping a flat plate of size 23 × 30 mm2 and bent two times to form a compact structure with dimensions 5 × 9 × 30 mm3. The PIFA was fed and short-circuited at the top patch above the antenna ground with a vertical ground wall connecting therebetween. The two PIFAs were symmetrically located on the metal cover and grounded therein. The results showed that comparable Eθ and Eφ fields of the antennas were obtained for the tablet computer used in the three major positions, namely landscape, portrait, and bottom-down modes. The correlation and the diversity gain of the two-PIFA system were also measured. The operating principle and details of the design prototypes are described and discussed in the article. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2815-2821, 2013 [ABSTRACT FROM AUTHOR]

ABSTRACT A small-size strip monopole antenna with dual feeds disposed at one corner of the supporting metal plate of the display of the tablet computer for LTE/WWAN operation is presented. The strip monopole is configured into a simple inverted-L shape of 29 mm (less than 0.08 wavelength at 750 MHz) and has a low profile of 10 mm above the two side edges of the corner. A first end of the strip monopole can be connected to a first ON/OFF switch (switch-1) for lower-band operation, while a second end of the strip monopole can be connected to a second ON/OFF switch (switch-2) for higher-band operation. When switch-1 is ON with switch-2 OFF, the antenna is fed at port-1. In this case, with the aid of a wideband matching circuit, the antenna can provide a wide lower band to cover the LTE band13 and GSM850/900 operation (746-960 MHz). When switch-1 is OFF with switch-2 ON, the antenna is fed at port-2 and can provide a wide higher band to cover the GSM1800/1900/UMTS/LTE2300/2500 operation (1710-2690 MHz). Good radiation characteristics for frequencies over the antenna's operating bands are also obtained. Operating principle of the antenna is described in the article. Experimental results and parametric studies of the antenna are presented. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2571-2576, 2013 [ABSTRACT FROM AUTHOR]

ABSTRACT In this article, we present the design of a dual-band (3.5 and 5.8 GHz), meandered monopole antenna for Wireless Local Area Network (WLAN)/Worldwide Interoperability for Microwave Access (WiMAX) applications, which is fed by an asymmetric coplanar strip (ACS). The proposed antenna is comprised of an asymmetric ground plane, an ACS-fed structure, and coupled meandered monopole-type of radiating elements that are designed to provide the two desired operation bands, namely 3.5 and 5.8 GHz. The two resonance frequencies of the antenna can be controlled by adjusting the dimensions of the radiating elements, namely the two meandered monopoles, and the gap between them which controls the coupling. The designed antenna has a small size, which is only 20 × 12 mm2 including the ground plane. Simulated and measured results are presented to demonstrate that the proposed dual-band antenna is well suited for WLAN and WiMAX applications. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2370-2373, 2013 [ABSTRACT FROM AUTHOR]

ABSTRACT A rectangular slot antenna fed by a coplanar waveguide is proposed for dual-band wireless local area network (WLAN) operations. The measured −10-dB bandwidth for return loss is from 2.1 to 2.95 GHz and 5.05 to 6.25 GHz, covering all the 2.4/5-GHz WLAN bands. A multifeed four-element planar array was designed and simulated. It shows that the features of small size, uniplanar structure, good radiation characteristics, and small mutual coupling are promising for multi-input multi-output applications. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2490-2493, 2013 [ABSTRACT FROM AUTHOR]

ABSTRACT This article presents a CMOS ultrawideband (UWB) impulse generator using a 0.13-μm CMOS technology for the application of UWB 22-29-GHz vehicular radar. The proposed impulse generator has a pulse-modulated carrier-based architecture. The proposed design is power efficient and spectrum controllable with a frequency tuning range of 800 MHz. The output impulse has a pulse width less than 0.55 ns providing a high range resolution for the UWB vehicular radar systems. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1881-1887, 2013 10.1002/mop.27715 [ABSTRACT FROM AUTHOR]

ABSTRACT This article presents a planar dual-band monopole antenna with a frequency-tunable band for use in wireless devices of the 2.4 and 3.4 GHz worldwide interoperability for microwave access (WiMAX) system. The antenna has two radiating branches acting as monopoles and resonating at around 2.4 GHz (lower band) and 3.4 GHz (higher band). A varactor is placed on the radiating branch responsible for the lower band. A very simple DC biasing circuit is designed for reverse-biasing the varactor. By varying the DC-bias voltages from 0 to 12 V for the varactor, the lower band of the antenna can be continuously tuned from 2.3 to 2.83 GHz, covering the frequency bands from 2.3 to 2.4 GHz and 2.5 to 2.7 GHz for the WiMAX system. The antenna has a small overall size of 40 × 35 × 0.8 mm3 with a compact radiator of only 14.5 × 8.2 mm2. The antenna performance in terms of reflection coefficient, radiation pattern, peak gain, and efficiency is studied using computer simulation. For verification of simulation results, the antenna is fabricated and measured. The feeding cable used in measurement causes substantial discrepancies between the simulated and measured simulation results. To study the cable effects, a computer simulation model is included for studies. With the cable model, the simulated and measured results agree very well. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1902-1907, 2013 [ABSTRACT FROM AUTHOR]

ABSTRACT The article presents the design of a compact dual-band monopole antenna with microstrip-fed for use in wireless devices in the worldwide interoperability for microwave access (WiMAX) system. The radiator of the antenna has a compact size of only 14.5 × 8.7 mm2 and consists of a short stem and two branches generating two frequency bands at around 2.4 and 3.5 GHz for the WiMAX system. The two frequency bands can be easily and independently set using the parameters of the two radiating branches. The antenna performance in terms of reflection coefficient, radiation pattern, peak gain, and efficiency is studied using computer simulation. For verification of simulation results, the antenna is fabricated and measured using the antenna measurement system Satimo Starlab. The feeding cable used to connect the antenna to the measurement system causes substantial discrepancies between the simulated and measured results. To study the cable effects, the feeding cable is modeled and used in computer simulation for studies. With the use of the cable model, the simulated and measured results agree very well. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1765-1770, 2013 [ABSTRACT FROM AUTHOR]

ABSTRACT In this article, a novel monopole antenna which consists of a radiating patch with two modified L-shaped notches to achieve broad bandwidth is presented for various mobile communication services such as wireless broadband, wireless local area network, digital mobile broadcasting, and ultrawideband (UWB) applications. The proposed antenna is designed to operate over 2-11.2 GHz for S11 < −10 dB. Details of the proposed antenna design approach and measured results are also presented and discussed. The novel monopole antenna has wide band impedance bandwidth, compact size, and low fabrication cost, which are suitable for communication services and UWB application. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1856-1860, 2013 [ABSTRACT FROM AUTHOR]

ABSTRACT For eight-band LTE/WWAN operation (704-960/1710-2690 MHz) in the Ultrabook or thin-profile tablet computer, a planar antenna of simple structure and small size is presented. The proposed antenna is obtained by modifying a simple planar inverted-F antenna and can be printed on one surface of a thin FR4 substrate of size 10 × 45 mm2 only. The antenna's lower band bandwidth is greatly widened by embedding a proper chip capacitor of 2.7 pF at the feeding strip. This chip capacitor combines with the antenna's shorting strip can control the excitation of a parallel resonance to modify the impedance matching of the antenna's lower band such that a widened bandwidth is easily obtained to cover the LTE700/GSM850/900 operation. Conversely, the antenna's upper-band bandwidth is also greatly enhanced by using a coupled section in the antenna's radiating strip and adding a parasitic shorted strip near the feeding strip, which lead to multiple resonant modes excited to form a wide bandwidth (>1 GHz) to cover the GSM1800/1900/UMTS/LTE2300/2500 operation. Owing to its small size and simple structure, the proposed antenna is very suitable to be applied in achieving an antenna array with high isolation for MIMO or dual talk (dual WWAN) operation. Promising high-isolation antenna arrays formed by the proposed antennas are presented. The obtained isolation between the antennas in the antenna array is better than 12 dB, and the envelope correlation coefficient is less than 0.15 for frequencies over the LTE/WWAN bands. Details of the proposed antenna and antenna array are presented. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1928-1934, 2013 [ABSTRACT FROM AUTHOR]

An isolation technique for two small-size triband wireless wide area network (WLAN) multiple-input multiple-output (MIMO) laptop computer antennas covering the 2.4/5.2/5.8 GHz bands is presented. The proposed WLAN MIMO antennas have measured isolation of better than −21 dB in the 2.4 GHz band and −32 dB in the 5.2/5.8 GHz bands in this study. In addition to enhanced isolation achieved, good antenna efficiencies of better than about 70 and 90%, respectively, in the 2.4 GHz and 5.2/5.8 GHz bands are obtained for the two antennas. The WLAN MIMO antenna array having a planar structure of size 9 × 55 mm2 is to be mounted at the top edge of the supporting metal plate of the laptop display. The two antennas can be fabricated at low cost on a thin FR4 substrate and are of a simple structure comprising a driven strip and a shorted strip, which provides two wide operating bands to cover the 2.4 and 5.2/5.8 GHz bands. Between the two antennas, there is an isolation element formed by a protruded ground plane and a spiral open slot embedded therein. The isolation element leads to enhanced isolation between the antennas in the 2.4/5.2/5.8 GHz WLAN bands and good antenna efficiencies for the antennas as well. Details of the isolation technique for the WLAN MIMO antennas are described, and the obtained results are presented and discussed. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:382-387, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27279 [ABSTRACT FROM AUTHOR]

A 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 [ABSTRACT FROM AUTHOR]

ABSTRACT In this article, we present a dual-band coplanar waveguide-fed slot antenna for 1.7/2.3 GHz long term evolution and wireless broadband frequencies. The proposed antenna is fabricated on an FR4 substrate with dielectric constant of 4.4. By cutting a pair of rotated T-shaped slits in the circular radiating stub, a new resonance at the lower frequencies is generated, and also by embedding a meander-line slit in the ground plane a good dual-band operation antenna can be achieved. The measured impedance bandwidth for 10 dB return loss is from 1.57 to 1.73 GHz (13%) and 2.21 to 2.38 GHz (10.0%), covering the 1.7/2.3 GHz for the dual-band wireless operations. Simulated and experimental results obtained for this antenna show that the proposed slot antenna has a good antenna gain and radiation behavior. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1013-1015, 2014 [ABSTRACT FROM AUTHOR]

ABSTRACT In this study, a compact circularly-polarized (CP) enhanced bandwidth instrument, scientific, and measurement (ISM) band (2.4-2.485 GHz) antenna with enhanced bandwidth is proposed for wireless body area network applications. To miniaturize the size and widen the CP bandwidth, two y-shaped strips connected to ground and a partially meandered strip feed line were used. The manufactured antenna has a 10 dB return loss bandwidth of 46% (2170-3290 MHz) and a 3 dB axial-ratio bandwidth of 29% (2110-2820 MHz). The maximum gain of the antenna is 4.87 dBic. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1738-1741, 2013 [ABSTRACT FROM AUTHOR]

ABSTRACT A compact, reconfigurable planar inverted-F antenna (PIFA) for mobile phone applications is presented. Based on recent smart-phone geometries, a PIN diode on an antenna radiator is used for frequency-reconfigurable operation with a PIFA structure. The proposed novel hexa-band built-in mobile antenna, which is designed to cover LTE, GSM850, GSM900, DCS, PCS, and UMTS bands, is satisfactory in terms of its reflection coefficient, radiation patterns, and average gain (efficiency). A prototype is investigated, and good agreement between simulations and measurements is shown. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1926-1928, 2013 [ABSTRACT FROM AUTHOR]