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In this paper is developed a transparent antenna, bioinspired in ingae edulis mart plants, build in Indio Tin Oxide film, and flexible transparent dielectric of low cost (cellulose acetate), generated by Gielis formula, for wireless local area network application in 5 GHz (5.15–5.85 GHz). The measured bioinspired transparent antenna presented bandwidth of 4.11 GHz (4.50-8.66 GHz), covering the WLAN band, with maximum gain of 5.44 dBi, and half power beamwidth of 126° at resonance frequency.

This letter presents a printed planar monopole antenna with triple-band operation. By adding two symmetrical split ring resonator (SRR) pairs to the primitive monopole antenna, the wireless local area network (WLAN), and worldwide interoperability for microwave access (WiMAX) bands operating at 2.45/3.5/5.8 GHz can be obtained. The inserted SRR pairs exhibit both the radiation and the nonradiation mode of operations, from which the proposed antenna works in triple band. The principle of how these two modes give us the multiband operation is explained. The antenna was fabricated and measured to confirm the characteristics of the proposed design. The simulated and experimental results are in close agreement. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:753–758, 2017

A 5-GHz highly linear floating-body CMOS low-noise amplifier (LNA) with switched gain control is presented. The proposed LNA achieves very low noise in gain mode and high linearity and very low power consumption in bypass mode. In the gain mode, the LNA consumes 19.5 mW of power and achieves a noise figure of 1.15 dB, a gain of 13.8 dB, and an input IP3 of 3 dBm at 5 GHz. In the bypass mode, the LNA consumes only 1 μW and achieves a gain of −4.3 dB and an input IP3 of 7 dBm at 5 GHz. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:593–596, 2017

A microstrip patch antenna array has been designed with 24 ultra-wide patch elements to improve the antenna gain up to around 20 dBi for 60 GHz band point to point wireless local area network (WLAN) and wireless personal area network (WPAN) applications. Both series and parallel feeding techniques have been collaborated to excite the patch elements. Reverse impedance matching method has been adopted to enhance the antenna's fabrication tolerance. The measured and simulation results showed a close agreement. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:511–514, 2017

A multiple-input–multiple-output (MIMO) antenna with high frequency selectivity and controllable bandwidth, is proposed for band-notched ultrawideband (UWB) applications. In other words, it has a bandstop-filter-like response (second-order notched band) at the aimed rejected band. It consists of two rectangular printed monopole (PM) elements and a simple stepped ground stub to enhance wideband isolation. For achieving the second-order rejected band of the IEEE 802.11 wireless local area network (WLAN) band from 5.15 to 5.85 GHz centered at 5.5 GHz, two parasitic modified split-ring resonators (PMSRRs) and two inverted L-shaped branches (ILBs), are utilized. Measured results prove a bandwidth of S11

This letter presents a wide-slot monopole antenna loaded with a dual-ring resonator for triple-band operation, which can be applied for wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX). Multiband operation is realized by incorporating a fork-like monopole, a wide slot, as well as a dual-ring resonator. The desired lower bands of 2.4 GHz WLAN and 2.5 GHz WiMAX operations can be obtained by replacing the traditional ground with a wide-slot ground. Then, with the addition of the dual-ring resonator coupled fed by the fork-like monopole, the middle resonate mode covering 3.5 GHz WiMAX occurs. In addition, an upper operation band, which is generated by the fork-like monopole, can be further widened by the wide-slot ground to cover the 5.2/5.8 GHz WLAN and 5.5 GHz WiMAX. A prototype of the proposed antenna with a compact size of 32 × 28 mm2 has been designed, fabricated, and tested. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1097–1101, 2016

In this paper, a compact microstrip fed octagonal ring dual band antenna for integrated Bluetooth (2.4∼2.484 GHz) and ultra-wideband (UWB; 3.1∼10.6 GHz) applications withband notch characteristics for wireless local area network (WLAN; 5.15∼5.825 GHz) is proposed and investigated. The entire UWB frequency band is achieved by using an octagonal ring patch and a modified ground plane. The dual band operation is achieved by integrating Bluetooth characteristicsby embedding a quarter wavelength resonating strip at the center of the octagonal ring radiating patch. Further, to avoid the potential interferences of the UWB system with the existing narrow band system such as WLAN in the proposed antenna,an inverted U-shaped slot in the feed line has been etched to obtain the desired band notch characteristics. The proposed antenna is designed, fabricated on a FR4 glass epoxy substrate and tested. The proposed antenna yields a measured impedance bandwidth over the frequency range of 2.40 ∼ 2.5 GHz and 3.1 ∼ 13 GHz to exhibit the integrated Bluetooth and UWB characteristics respectively for VSWR

In this letter, L-T slots-loaded dual-band elliptical polarized antenna etched on a single layer substrate is proposed. This antenna is composed from four T-shaped slots near patch boundary and two pair of L-shaped slots etched at patch corner with a rectangular slot located at the center. These combination slots are found out to produce two different frequency bands for LTE and wireless local area network application. The lower band of 2.5–2.69 GHz and the upper band of 5.725–5.85 GHz are controlled by the T-shaped slots and L-shaped slots, respectively. By symmetrically slots and properly positioning the feed position, the proposed antenna exhibits high gain of 6.91 dBi and 7.22 dBi at 2.6 GHz and 5.8 GHz, respectively, even with the compact dimensions of 44 × 44 × 1.6 mm3. Due to the orthogonal surface currents at first and third resonant modes, the proposed antenna gives an elliptical polarization with axial ratios of 7.536 dB at 2.656 GHz and 5.76 dB at 5.8 GHz. The simulation and measurement results of reflection coefficient, gain, and radiation pattern are comparable. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:184–188, 2016

Light-emitting diode-based (LED) visible light communication (VLC) has become a candidate in next generation ultrahigh-speed indoor wireless local area network. Within this scenario, it is most likely for a receiver to obtain the signals from multiple LED sources, which in general brings about interference among the transmitters and may result in failure detection. In this article, space-time block coding (STBC), as a representative multiple antenna techniques, is adopted to enhance the VLC network performance for its effective suppression on the intertransmitter interference. We experimentally demonstrate a multiple input single output VLC network consisting of two RGB-LEDs. Using STBC-OFDM Coding, a total throughput of 500 Mb/s is achieved and the free space transmission reach can be extended as long as 5 m. As far as we know, it is the fastest speed and longest distance in multiple antenna VLC network using STBC coding. Both theoretical simulation and experimental investigation reveal great improvements in the robustness, flexibility, and compatibility of a LED-VLC network due to the appropriate coding scheme. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:2943–2946, 2015

A compact triband CPW-fed monopole antenna for wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications is proposed in this letter. The antenna consists of a rectangular ring, a pair of F-shaped stubs, and a rectangular monopole radiator. By optimizing the designed parameters of these structures, three separate resonant modes are generated to cover the desired bands. A prototype of the proposed antenna with a compact size of 23 × 36 mm2 is fabricated and tested. Measured results show that the antenna has the impedance bandwidths of 240 MHz (2.35–2.59 GHz), 620 MHz (3.31–3.93 GHz), and 1280 MHz (5.07–6.35 GHz) with reflection coefficient less than −10 dB, which can cover both WLAN in the 2.4/5.2/5.8 GHz bands and WiMAX in the 3.5/5.5 GHz. In addition, good radiation patterns are also achieved in both E- and H-planes. Based on the measured results, the proposed antenna is a good candidate for WLAN and WiMAX applications. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:2298–2303, 2015

A microstrip-line feed simple design of modified rectangular slotted patch antenna is proposed for dual-frequency operation. The typical rectangular shape of the patch is reformed by integrating slots and extending the radiating patch to some extent for achieving desired resonance. With the optimized dimensions from numerical simulating software, the proposed antenna is printed on 1.905-mm-thick 40 × 40 mm2 ceramic composite substrate with relative dielectric constant er = 10.2. The experimental results confirm the bandwidths for S11 ≤−10 dB are of 780 MHz (1.13–1.91 GHz) and 1.22 GHz (4.83–6.05 GHz) with resonance frequency 1.48 and 5.61 GHz, respectively. The antenna prototype shows almost consistent and symmetrical radiation patterns with maximum gain of 3.42 and 4.37 dBi for lower and upper frequency band, respectively. On the basis of well-agreed simulated and measured results, adequate bandwidth, stable radiation, and acceptable gain performance make the antenna suitable for serving simultaneously in global positioning system and wireless local area network bands. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:2204–2207, 2015

A compact triple frequency microstrip antenna for WLAN/WiMAX applications is presented in this work. The proposed antenna consists of a rectangular microstrip patch embedded with an inverted L-shaped open ended slot and a ground plane with horizontal H shaped and rectangular slots. The designed antenna operates over the frequency ranges 2.30–2.751, 3.199–3.816, 5.06–6.15 GHz necessary for 2.4/5.2/5.8 GHz WLAN and 2.3/2.5/3.5/5.5 GHz WiMAX applications. Maximum size reduction of the proposed antenna obtained is about 83.17%. Good agreement is achieved between simulated and measured results. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:2125–2129, 2015

In this article, a very compact printed asymmetric rectangular monopole antenna with an electrically coupled split ring resonator (SRR) is presented. The operating frequencies cover the worldwide interoperability for microwave access (WiMAX), wireless local area network (WLAN), and ultra wideband (UWB) applications. The asymmetric monopole is fed by a microstrip line, whereas the SRR is inductively coupled with the radiating element. The electric field-coupled SRR yields its resonance at 3.5 GHz in addition to the fundamental wideband resonance obtained by the asymmetric monopole. The measured operating bands (3.48–3.62 GHz), (5.1–11.12 GHz) are suitable for WiMAX and 5 GHz WLAN bands. Consequently, the overall operating bands of the antenna cover the UWB range with the exception of 3.1–3.48 and 3.62–5.1 GHz range. The proposed antenna has a very compact size of 13 × 15 × 1.6 mm3. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:2194–2197, 2015

A compact microstrip-fed multiband planar antenna for global positioning system, worldwide interoperability for microwave access, and wireless local area network applications is presented. Three operating frequency bands are achieved by a pair of L-shaped slots and rectangular slots, and defected ground structure. The fabricated prototype for the proposed antenna occupies an area of 32 × 22.6 mm2. The measured results show that the proposed antenna has 10 dB impedance bandwidth of 420 MHz (1.34–1.76 GHz), 590 MHz (3.21–3.80 GHz), and 1.5 GHz (5.05–6.55 GHz). The proposed antenna shows good radiation patterns and acceptable gain over three operating bands. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1769–1773, 2015

A nonuniform inverted-L Slotted double-sided array antenna for Long Term Evolution (2.6 GHz) and Wireless Local Area Network (5.8 GHz) application is presented in this article. The proposed antenna is a combination of 4 × 2 radiating element array at the both sides of the FR4 substrate where the both side array are designed reciprocally opposite to each other. It is found that double-sided array with nonuniform inverted-L slot suppresses the side lobe less than −20 dB at both frequencies. The 3-mm air gap which separates the substrate and reflector is discovered to enhance further the reflection coefficient and gain. The upper side plane with smaller inverted-L slots generates 5.8 GHz frequency and capable to achieve gain of 10.1 dB. Meanwhile 7.11 dB of gain at 2.6 GHz frequency is produced by the lower side plane with bigger inverted-L slots. The proposed antenna achieves acceptable reflection coefficient at both operated frequencies for simulation and measurement. However, the reflection coefficient at the lower frequency 2.6 GHz reaches −17.588 dB (simulated) and −15.84 dB (measured) and at the upper frequency 5.8 GHz is about −12.26 dB (simulated), −15.71 dB (measured). Good agreement is obtained between simulated and measured result for E-plane and H-plane radiation pattern at both frequencies. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1915–1919, 2015

In this research, a new frequency-reconfigurable triple-band antenna for wireless applications achieved using lumped inductor is proposed. The each three working bands can be separately and continuously reconfigured by changing the values of the lumped inductors with the radiation patterns nearly unchanged. Besides, the working state can also be modulated to make the antenna operate at single-band/dual-band by selecting certain values of the lumped inductors. By introducing a via hole connecting the top layer patch with the bottom layer patch, a miniaturized size of 29 × 15 × 1.6 mm3 can be achieved. The designed antenna has wide tunable band and can effectively covering 2.4/5.2/5.8 GHz Wireless Local Area Network and 3.5/5.5 GHz Worldwide Interoperability for Microwave Access bands. Besides, the designed antenna can also be applied for GSM850, GSM900, DCS1800, PCS1900, GPS, and 3G bands. The measured results have good agreement with the simulated results. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1374–1379, 2015

This article presents an antenna with the characteristics of flexibility and transparency for use in laptop computers. The operating frequency band of the antenna is 5.18–5.32 GHz, in wireless local area network 802.11a service. The proposed antenna was fabricated on a polyamide substrate, and the conducting material for the antenna consisted of a multilayer film (IZTO/Ag/IZTO). In addition, we designed and measured two antennas with two electrodes (IZTO/Ag/IZTO and Ag) to compare and evaluate their performance and transparency. Moreover, we applied this antenna to laptop application and simulated and measured the performance dependence of the antenna by both the position and angle with the display plane (ground) of the laptop. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1038–1042, 2015

In this article, a dual-band narrow bandpass filter using U-shaped stepped-impedance resonator (SIR) for 2.4/5.2 GHz wireless local area network (WLAN) application is proposed. The filter is composed of a simple U-shaped SIR and novel feedlines with two open stubs. Furthermore, this article relatively used the first and second resonances to achieve the dual-band performance. To validate the design and analysis, a prototype filter has been fabricated with two passbands are centered at 2.4 and 5.2 GHz with the fractional bandwidth of 4.9 and 3.5%, respectively. Its excellent selectivity is suitable for WLAN application. The measurement performances show good agreements with the simulated ones. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1143–1146, 2015

The design of a small size 50 × 50 mm2 coplanar waveguide-fed square ring slot antenna is studied. To attain circular polarization (CP) radiation with broad 3-dB axial ratio (AR) bandwidth that can cover the worldwide interoperability for microwave access 2.3 GHz (2305–2320 MHz, 2345–2360 MHz) and wireless local area network 2.4 GHz (2400–2480 MHz) bands, a novel technique of extending a C-shaped branch from the vertical monopole is proposed. Good impedance matching and CP performance was achieved by further extending a vertical tuning strip from the C-shaped branch. From the measured results, 10-dB impedance bandwidth and 3-dB AR bandwidth of 63.89% and 7.93% were achieved. Furthermore, stable gain variation of approximately 2.7 dBic and radiation efficiency of more than 85% were also exhibited across the bands of interest. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:886–891, 2015

In this article, a study of a triple band notched circular ring monopole ultrawide band (UWB) antenna is presented. The UWB antenna consists of a circular ring radiating patch and rectangular ground plane with two small slots near the feed line for bandwidth enhancement. The proposed antenna can reject worldwide interoperability for microwave access (WiMAX) band (3.3–3.8 GHz), wireless local area network (WLAN) band (5–6 GHz) and X-band downlink satellite communication band (7.1–7.9 GHz). The WiMAX and WLAN band rejections are realized by introducing two arc shaped elliptical slots and single elliptical split ring slot in the radiating patch, respectively. Furthermore, a pair of rectangular single split ring resonators is used to obtain the rejection of X-band downlink satellite communication signal. The proposed UWB antenna is fabricated and measured. The measured results are in good agreement with the simulated ones. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:668–672, 2015

A low power, high gain, and low-noise figure (NF) 5–6 GHz low-noise amplifier (LNA) with excellent reverse isolation in a cost effective 0.18 μm CMOS technology is reported. To achieve sufficient power gain (S21) and reverse isolation (S12), the LNA comprises an inductive source-degeneration cascode stage followed by a cascode stage. The LNA consumes 7.99 mW, achieving high S21 of 19 ± 1.5 dB for frequencies of 5.1–6.2 GHz and excellent S12 of −67.9 to −73.3 dB for frequencies of 5–6 GHz. In addition, the LNA achieves minimum NF of 2.8 dB at 5.5 GHz and NF of 2.91 ± 0.11 dB for frequencies of 5–6 GHz, one of the best NF results ever reported for a 5-GHz-band CMOS LNA. To verify the 5-GHz LNA, a test IEEE 802.11 wireless local area network (WLAN) transceiver based on the LNA is also designed and implemented. The measured results show that for the 24 channels in 5-GHz band, the average sensitivity is −77 and 3 dBm better than that (−74 dBm) of the conventional one. A conventional one means the 802.11 WLAN controller in this work is replaced by a commercial RTL8812AR-VN WLAN controller. In addition, the average error vector magnitude of received IQ data is −32 dB (or 2.5%), 2.5 dB (or 0.8%) better than that (−29.5 dB [or 3.3%]) of the conventional one. The impressive results from this work indicate the high potential of the proposed LNA in 5-GHz WLAN applications. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:296–304, 2015

A slot meander spurline bandstop filter (BSF) is designed, fabricated, and characterized on a semi-insulating-GaAs substrate with a thickness of 625 µm and a dielectric constant of 12.85 using integrated passive device technology. The BSF is resonated at 5.44 GHz for wireless local area network applications. The purposed bandstop is built with slot meander spurlines and symmetrically folded T-type slot lines that provide excellent S-parameter responses. The measured insertion loss (S21) and return loss (S11) are −28.7 and 0.7 dB, respectively, with a 3-dB fractional bandwidth of 11%. The experimental results nearly have a good agreement with the simulation results. The overall dimension of the proposed BSF is (1966 × 4984) µm2. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:168–172, 2015

In this article, a novel coplanar waveguide (CPW)-fed monopole antenna with three branch strips for wireless local area network (WLAN)/worldwide interoperability of microwave access (WiMAX) triple-band applications is proposed. The proposed antenna is simply composed of three branch strips. By carefully selecting the positions and lengths of these branch strips, the desired resonant modes excited at 2.46/3.6/5.4 GHz with less than −10 dB frequency responses to the impedance can be achieved. In addition, an acceptable agreement is obtained between the simulation and the experiment. Also, the compact design of the proposed antenna, which has enough impedance bandwidth, makes the antenna suitable for WLAN and WiMAX operations. This article further presents and discusses the 2D radiation patterns and 2D gains according to the experiment results. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:161–166, 2015

In this article, a combination of microstrip bandpass filter and antenna is presented to give sharp response at desired frequency bands along with very low insertion loss. Three single bandpass filters, designed at wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) frequency bands, are integrated into a tri-band bandpass filter. An ultrawideband antenna is further added to the structure. The antenna operates in 2.23–2.587, 3.468–3.816, and 5.345–5.607 GHz, suitable for WLAN 2.4 GHz and WiMAX 3.5/5.5 GHz applications. The proposed tri-band filtering antenna shows monopole-like radiation patterns in the desired frequency bands with high out-of-band rejection. Good agreement between simulated and measured results validates possible applications. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:233–237, 2015

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

The present work represents a dual-band microstrip-fed patch antenna in which the radiating structure is formed with a pair of inverted L-shape patches and ground plane is being modified to a -shape. Both the radiating patch and modified ground plane are perfect electric conductors. The patch is printed on a readily available Epoxy Glass (FR-4) substrate with thickness 1.6 mm, relative permittivity 4.4, and loss tangent 0.0024. The proposed microstrip patch antenna (MPA) design is capable of generating two distinct operating bands with 10-dB return loss as follows 3.34–3.54 GHz and 4.90–6.26 GHz with adequate bandwidth of 200 MHz and 1.36 GHz, respectively. The impedance bandwidths are wide enough to cover the required bandwidths of 3.3–3.5 GHz, 5.15–5.35 GHz, 5.725–5.825 GHz for wireless local area network, 3.3–3.5 GHz for multiple input multiple output, 5.25–5.85 GHz for world-wide interoperability for microwave access, 5.650–5.670 GHz for uplinks and 5.830–5.850 GHz for downlinks of Amateur Satellite, and 5.9 GHz wireless access in the vehicular environment (WAVE-IEEE 802.11p). Proposed MPA was simulated using Computer Simulation Technology Microwave Studio V9 based on the finite integration technique with perfect boundary approximation and effect of using different substrate materials was studied. Finally, the proposed antenna with optimized parameters was fabricated and some performance measurements were taken to validate against simulation results. The design procedure to achieve the required performance are presented and discussed. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:988–993, 2014; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.28206. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1965–1970, 2014

This article presents a low-profile dual band printed Inverted-L (IL) shaped monopole antenna with Parasitic Inverted-F (PIF) shaped element in the ground plane for 2.4/5.2/5.8 GHz wireless local area network applications simultaneously. Owing to coupling 006-Ff microstrip line-fed IL driven element and PIF element, a compact radiator of 8 × 12 mm2 is realized and tested. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1163–1167, 2014

A microstrip-fed slot antenna design for wireless local area network 2.4/5 GHz applications is proposed. To achieve dual-band operation that composed of four resonant modes located at approximately 2.28, 2.69, 5.36, and 5.94 GHz band, three separate slots are embedded into the ground plane, in which two of the slots are devised as step-impedance types, and one of the slots is an L-shaped slot type. By meticulously arranging the positions of these three slots located above the microstrip-fed line, two broad operating bands that operate between 2140–2750 MHz (∼25%) and 5050–6160 MHz (∼20%) are achieved. Detail process of designing the proposed antenna is explicitly shown, and vital parametric studies were also conducted by simulation. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:983–988, 2014

A novel reconfigurable band-pass filter for worldwide interoperability for microwave access (WiMAX)/wireless local area network (WLAN) applications is presented. By using an H-shaped strip with a pair of C-shaped slots in the band-pass filter two new resonances can be achieved. The proposed band-pass filter has three different switchable states: 2.25–10.72 GHz in WLAN mode, 3.34–3.71 GHz in WiMAX mode, and 1.65–1.89 GHz in narrowband mode. The band-pass filter which uses a switchable slotted structure for reconfigurability has a simple structure and smallest size in comparison to band-pass filters reported in literature (Kikkert, TENCON 2005 IEEE region 10, 2005, Fan et al., Prog Electromagn Res 75 (2007), 285–293, Wang et al., Prog Electromagn Res 77 (2007), 67–73, Ojaroudi et al., Advanced electromagnetics symposium, 2012, Zhao et al., Prog Electromagn Res B 3 (2008), 131–141). Also the proposed filter has a major advantage in providing tighter capacitive coupling to the line in comparison to known radiating strip. To generate DC isolation in the RF path, we use a pair of gap distances in the microstrip loop. Simulated and experimental results obtained for this band-pass filter show that the proposed band-pass filter has a good return and insertion loss within the WiMAX/WLAN frequency range. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:509–512, 2014

In this article, a method for simultaneously enhancing the gain and reducing the size of microstrip antennas using a spiral complementary openings resonance ring (CSRR) structure ground plane has been presented. The proposed antenna is successfully designed and measured, which provides frequency band from 5.145∼5.387 GHz. By adjusting the size of the spiral CSRR on the ground plane, small size antenna of 25 × 25 × 0.8 mm3 and 5.8 dBi of relative high gain are achieved. Comparing the simulated and measured results confirm the suitability of the proposed antenna for wireless local area network application. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:117–120, 2014

A new, small-sized, multiple-loop-antenna system easily constructed from a single metal plate and able to generate concurrent 2.4 and 5 GHz bands for wireless local area network (WLAN) operation is presented. The design comprises four one-wavelength loop antennas, arranged perpendicular to and set along a square antenna ground, and occupies overall dimensions 10 mm × 75 mm × 75 mm. The four loops and the antenna ground were all integrated into one-piece flat plate. The loop was bent few times in a compact fashion such that parts of the antenna resonance path were merged into the ground plane. In this case, a multiantenna system with a simple structure and compact size was achieved for the WLAN applications. Good radiation characteristics were also obtained. Details of the design are described in the article. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:208–215, 2014

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

A novel design of a dual-band array antenna for Wireless Local Area Network and Worldwide Interoperability for Microwave Access applications is presented in this article. The antenna operates at 3.5 dBi (the lower band) and 5.8 GHz (the upper band), with gains of 7.8 and 5.5 dBi, respectively. The corresponding percentage bandwidths are 2.85 and 2.40%. The overall length of the feeding network was reduced significantly because the elements in the array are closer to each other, with a separation of less than keff/4. There is good agree- ment between simulation and measurement results. The results of the surface current study also are presented. V C 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2680-2686, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27942

A novel printed microstrip-fed monopole ultra-wideband antenna with dual notch-band is presented in this article. By inserting a meandering slot between the feed-line and the radiation patch, a lower notch-band is generated at 3.3–3.7 GHz (worldwide interoperability for microwave access). And, with adding a pair of symmetrical C-shape strips to the feed-line, an upper notch-band at 5.15–5.85 GHz (wireless local area network) is also achieved. To adjust notch-band at proper position and with appropriate bandwidth, the two symmetrical strips are optimized and discussed. The prototype of the proposed antenna is fabricated and measured. The simulated and measured results, including voltage stand wave ratio, radiation pattern, and group-delay, match well. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2631–2636, 2013

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

In this article, a compact and small coplanar waveguide fed (CPW-fed) monopole antenna is proposed for wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications. In the proposed antenna, the main target is to present a compact structure with a step-by-step design procedure on the patch. The antenna consists of a slotted rectangular patch as radiator, a partial CPW-ground plane. To excite WiMAX/WLAN bands, two F-shaped slits are inserted into the rectangular patch that resonates at the frequencies of 3.5 and 5.4 GHz. By suitable adjusting the lengths of the F-shaped design, much wider impedance bandwidth can be produced, especially at the lower band of WLAN/WiMAX. The size of the antenna is 15 × 15 × 1.6 mm3. A prototype of the designed antenna is constructed and experimentally investigated. The −10 dB S11 bandwidths of them are (3.15–4.63 GHz) and (4.75–6.62 GHz), respectively, which can cover both the WLAN bands (5.15–5.35 GHz and 5.725–5.825 GHz) and the WiMAX bands (3.4–3.6 GHz and 5.25–5.85 GHz). Proper omnidirectional radiation pattern characteristics and enough gains are obtained over the operating bands. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2337–2340, 2013

Despite being widely used, branch-line couplers (BLC) still suffer from large size. This makes it difficult to incorporate BLC into miniature microwave devices. The work presented here is the design and implementation of a 3-dB reduced-size wide-band 3-branch-line coupler (3-BLC). By combining meander line, cross, and two-step stubs techniques, size reduction and bandwidth improvement is successfully achieved on 3-BLC design. The 3-BLC length was reduced along the horizontal branches using two-step reduction technique while the center vertical branch was reduced using cross stubs. A simple two-turn meander line is utilized at the two ends vertical branches of the coupler to obtain balanced length with the middle vertical branch. Hence, its width was optimized to maximize the coupler bandwidth. The 3-BLC was designed to operate at 2.45 GHz wireless local area network frequency band (IEEE 802.11 b/g) and fabricated on a 1.6 mm thick FR-4 board. The simulated and measured results are in very good agreement and show a fractional bandwidth of 50% and a sized reduction of 61.64% at the center of the frequency band. The proposed coupler design provides BLC that occupies less space, simple to implement, and wide-band BLC architecture with generic 3-BLC wide-band characteristics retained. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1810–1815, 2013

In this article, a novel compact and high performance microstrip diplexer is designed for global position system (GPS) and wireless local area network (WLAN) applications. The compact diplexer consists of two filters with short centered stepped impedance resonators (SCSIRs) and quarter-wavelength resonators (QWRs), operated at 1.575 GHz and 5.8 GHz, respectively. Due to the intrinsic characteristics and mutual loading effect of two filters, multiple transmission zeros can be generated to achieve sharp skirt, wide stopband, and high isolation of the diplexer. Moreover, more compact size can be obtained without the extra junction matching. Finally, a microstrip diplexer with 1 dB absolute bandwidth 100 MHz for GPS channel and 1 dB fractional bandwidth (FBW) of 3.45% at 5.8 GHz for WLAN channel is designed and fabricated. The simulated and measured results show a better agreement and validate the proposed theory. The size without the 50 Ω feedline is only 0.156 λg × 0.103λg, in which λg is the guided wavelength at 1.575 GHz. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1233–1237, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27550

A nonconcentric crescent slot antenna design for wireless local area network (WLAN) operation is proposed. The antenna has a single radiating slot for dual-band operation and a simple feeding structure for impedance matching. It provides two 10-dB impedance bandwidths of 115 MHz (ca. 4.7% centered at 2.45 GHz) and 1130 MHz (ca. 20.5% centered at 5.5 GHz). The nonconcentric crescent slot design covers the 2400–2484 and 5150–5825 MHz bands of WLAN operations. The return loss, radiation performance, and magnetic current distributions are studied and discussed. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1081–1085, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27491

This paper presents a UWB low noise amplifier (LNA) for 3.1–10.6 GHz applications, with an excellent attenuation at 5–6 GHz for rejecting the wireless local area network (WLAN) interference. A method of canceling the on-chip inductive resistance has been employed in this work to make the inductor an extremely low loss inductor with a very high quality factor. The fully integrated UWB LNA is designed in the CMOS 0.18 μm Taiwan Semiconductor Manufacturing Company (TSMC) technology. Measurement results show that the LNA achieves attenuation of up to 39 dB at 5.4 GHz, while the 1 dB power gain is 10 dB. The measured return losses (S11 and S22) are better than −7.4 dB while the noise figure is 5–6.1 dB in the range of operation. The measured input P1dB and IIP3 measured at 6.5 GHz are −12.2 and 2 dBm, respectively. The designed LNA occupies an area of 1.105 × 0.68 mm2. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:894–899, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27464

A compact ultrawideband (UWB) antenna with two band-notched characteristics is presented and investigated in this article.Two conformal U type slots are etched on the patch to generate two notched bands at 3.5 and 5.2–5.8 GHz, which contribute good rejection of interference with WiMAX (3.5 GHz) and wireless local area network (5.2–5.8 GHz), each of which can be controlled independently. The presented antenna can provide an UWB bandwidth with expected notched band, and it has omnidirectional radiation pattern and stable gain at working frequencies according to simulation and measurement results. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:583–586, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27369

A coplanar waveguide fed ultra-wideband antenna with four band-notched characteristics is proposed in this letter.Two split ring slots are etched on the patch and two inverted L-shaped slots on the ground to generate four notched bands at 2.4, 3.5, 5.2, and 5.8 GHz, respectively, thus contribute good rejection of interference with WiFi (2.4 GHz), WiMax (3.5 GHz), and wireless local area network (5.2 GHz/5.8 GHz). The simulation and measurement show that the proposed antenna can guarantee a wide bandwidth from 2 to 12 GHz with stable gain and omnidirectional radiation pattern. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2862–2865, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27184

In this article, we propose a dual-band angled printed dipole antenna with wide beamwidth for use in the access points of wireless local area network operating in the 2.4- and 5-GHz bands.The antenna is fed by a novel integrated balun consisting of a curved microstripline and a circular slot for broadband operation. An angled dipole and two vertical copper plates on the ground plane are used to achieve wide beamwidth in the lower and upper bands, respectively. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2806–2811, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27176

In this article, a printed ring shaped monopole ultra-wideband antenna with band-notched feature is presented and investigated. To get the band-notched characteristic, a quarter wavelength tuning stub is embedded into the ring radiator. The measured results show that the proposed antenna meets the requirement of wide working bandwidth of 3.1–10.6 GHz with VSWR < 2, while avoiding the interference with the wireless local area network band (5.150–5.825 GHz). The transfer function (amplitude of S21/group delay) and time domain characteristic (fidelity/power spectrum density) are also studied in this article. The proposed antenna has a compact size, good radiation characteristics, ultrawide bandwidth, and good time-domain behaviors to satisfy the requirement of the current wireless communications systems. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2387–2392, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27067

This letter presents a developed ultrawideband bandpass filter with reconfigurable notches to suppress the interference from wireless local area network services.The filter with discrete tuning provision is built in microstrip line that consists of ring resonator, interdigital coupling, and embedded open stubs (EOS). The reconfiguration is realized using a pair of fast switching diodes that are placed between EOS and strip line. The filter provides an excellent wide bandwidth (from 1.8 to 7.8 GHz) and rejection performance of −41 dB at 2.6 GHz and −24 dB at 5.3 GHz. The total size of the developed filter with the above features is 39.2 × 6 mm2. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2423–2426, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27065

In this study, a novel dual-band planar monopole antenna for wireless local area network (WLAN)/ Worldwide Interoperability of Microwave Access (WiMAX) application was designed, fabricated, and measured. The proposed antenna consists of two hook- shaped strips, an asymmetric ground plane, and a rectangular slit in the ground plane. Acceptable agreements between the measured and simulated results are achieved. Numerical and experimental results demonstrate that the proposed antenna satisfies the 10 dB impedance bandwidth requirement while covering the WLAN and WiMAX bands simultaneously. This paper also presents and discusses the 2D radiation patterns and 3D gains according to the results of the experiment that was conducted.