Search

A dual-band antenna with large frequency ratio for microwave and millimeter-wave applications based on the dual-mode coplanar waveguide (CPW) transmission line is investigated in this letter. The dual-mode operation of the transmission line is obtained by introducing a rectangular stub to traditional CPW, which can provide different phase shift in different frequency bands. In the millimeter-wave band, the dual-mode transmission line can support odd mode while it supports even mode in the microwave band. Based on this, the dual-band antenna which operates as monopole antenna in the microwave band and Vivaldi antenna in the millimeter-wave band is realized using the same aperture. Moreover, the radiation structure for monopole in the microwave band is designed to enhance the radiation performance of the antenna in the millimeter-wave band. For verifying, the prototype of the antenna is fabricated on a Rogers 4003 substrate with an overall size of 45 × 20 × 0.508 mm3 and the measured results agree well with the simulated ones.

In this letter, a high selectivity filtering magnetoelectric (ME) dipole antenna with harmonic suppression is investigated. By etching a complementary split resonant ring (CSRR) on shorted wall of ME dipole, a radiation null at upper passband edge can be obtained. The intrinsic radiation null at lower passband edge of ME dipole is utilized, together with the radiation null generated by CSRR, to obtain high selectivity. In addition, to suppress the third harmonic of the antenna, a stepped impedance resonator is loaded on the Г-shaped feeding structure. For verifying, a prototype operating from 1.44–2.79 GHz is designed, fabricated, and measured. Compared with the traditional ME dipole antenna, the proposed filtering antenna shows upper and lower stopband rejection levels as high as 16.61 and 17.84 dB, respectively. Furthermore, a third harmonic suppression level of 12.78 dB is obtained. Good agreement can be observed between the simulation and measurement.

A reconfigurable antenna with radiation pattern and polarization reconfiguration capabilities is investigated in this communication. The antenna consists of a central dielectric resonator antenna (DRA) and two parasitic DRAs made of a liquid solution with low dielectric loss. Utilizing the flowing of liquid, the existing of parasitic DRA can be changed to produce different patterns. An omnidirectional pattern can be realized when only the central DRA radiates, while a unidirectional pattern can be obtained using the parasitic DRAs. Furthermore, the polarization of the antenna with unidirectional radiation can be changed by forming different parasitic DRAs, which can be realized via liquid flowing. Based on this principle, three different radiation states, namely, omnidirectional radiation and unidirectional radiation with $x$ - or $y$ -polarization, can be obtained. To verify the design, a prototype of the antenna operating at 2.4 GHz was simulated, fabricated, and measured. The measurement results indicate that the antenna provides effective impedance matching over the band of interest as well as radiation pattern and polarization reconfiguration capabilities.

A broadband printed dipole fed by a balun with third-order impedance matching is proposed in this paper. Firstly, a circuit model of the antenna is given based on the principle of marchand balun. The balun is composed of a stepped impedance microstrip line and marchand balun, which form a three-stage match and its good broadband characteristics are verified by ADS. Furthermore, a printed dipole antenna is integrated using the proposed balun, and the results show that the antenna is obtained a wide impedance bandwidth of 72.7% for VSWR < 2.

In this paper, a new design method of microstrip series-fed array antenna for vehicle radar technology is proposed. The energy transmission and radiation between antenna elements are expressed and deduced using S-parameters in this method. A constant-amplitude and in-phase microstrip series-fed array antenna is designed through the analysis of this method. The results show that the bandwidth of the antenna ranges from 23.78 GHz to 24.27 GHz for| S 11 | < −10 dB and the gain is 12.35 dBi at the center frequency.

This paper presents $\mathrm{a}\pm 45$ degree polarization reconfigurable antenna based on liquid medium. The antenna consists of a central dielectric resonator antenna (DRA) and three liquid DRAs (The liquid medium is ethyl acetate with low dielectric loss and low toxicity). The DRA on the y-axis keeps the liquid filled, and the other two parasitic DRAs on the x-axis work through the flow of liquid medium to realize the unidirectional radiation. The polarization of the antenna changes with the selection of different parasitic DRAs, which is generated by the flow of liquid medium. Based on this principle, two polarization modes (the polarization is ± 45 degree to the positive direction of Y axis) perpendicular to each other can be obtained, which realizes the reconfiguration of polarization states. In order to verify the design of the antenna, an antenna operating at 2.4GHz band is simulated. The simulation results indicate that the antenna achieves effective impedance matching and sufficient antenna gain in the target operating frequency band, and also verifies its capability of polarization reconfiguration.

In this letter, a design for broadband circularly slotted patch antenna fabricated on a single- layered printed circuit board (PCB) with unidirectional radiation is described. It is fed by a simple center-fed feeding scheme. Unlike conventional slotted patch antennas, the proposed antenna is loaded with four short pins such that both matching and axial-ratio (AR) bandwidths are improved. In addition to realize the CP radiation at higher frequencies, a cross-slot with different arm lengths, which is cut from the center-fed patch is used. Then, the proposed antenna operates as magnetic dipoles to generate circular polarization at low frequencies after four short pins are added to connect the patch to the ground. Thus, by combining the two modes, bandwidths of 30.2% (1.83-2.48 GHz) for |S11| < �10 dB and 21.2% (1.98-2.45 GHz) for axial ratio (AR) < 3 dB around the center frequency of 2.15 GHz are measured. Moreover, stable gain of over 8 dBic and good radiation patterns are also observed across the operating band.

A wideband Tightly Coupled Dipole Array (TCDA) is presented in this letter, which consists of a printed bowtie element, a wideband slot balun feeding network, a multi-section microstrip feedline and a wide angle impendence matching layer(WAim). This type of antenna utilizes the coupling between unit antennas to achieve a wide bandwidth. The bowtie element and the balun are printed on a vertical printed circuit board. The unit cell is 0.5λhigh×0.5λhigh (λhigh is the free wavelength at the highest end of the frequency band). Simulated results show that the antenna can achieve a 3.8:1 bandwidth with VSWR≤ 3 at broadside and achieve a 4:1 bandwidth within ±45° scanning range in E and H planes with VSWR ≤ 3.

A wideband horizontally polarized (HP) omnidirectional antenna is proposed in this communication, which consists of 12 printed arc dipole units, a wideband 1-to-12 feed network, 2 rows of parasitic arc strips, and a row of director elements. Based on the tightly coupled dipole array design, 12 printed arc dipoles (about $0.2 \lambda_{\rm L}$ , $\lambda_{\rm L}$ : effective wavelength at low frequency) are formed as a ring with their edge overlap for strong mutual coupling. Meanwhile, the two rows of parasitic arc strips are radially placed around these arc dipoles as an impedance matching layer. Owing to the strong mutual coupling and impedance matching layer, the proposed HP omnidirectional antenna has a wideband operating band. Additionally, a row of director elements is utilized to enhance the radiation in horizontal plane. The printed arc dipoles are fed by a wideband 1-to-12 power divider with identical magnitude and phase. Experimental results show that this antenna has a wide 10-dB return loss operating bandwidth of 70.2% (1.7–3.54 GHz) and good omnidirectionality performance with gain variation in horizontal plane being less than 1.2 dB among 1.7–3.2 GHz.

A tri-band multiple-input-multiple-output (MIMO) antenna that covers all frequency bands required for WLAN and WiMAX applications is presented. Three resonant bands are achieved by a folded monopole with a compact size of 11.5 × 15. 6m m 2 . The MIMO system consists of two symmetrically placed monopoles. A stepped slot ended with an ellipse on the ground plane is etched to reduce the mutual coupling between the two monopoles. The overall dimension of this MIMO system is 50 × 50 mm 2 . The prototype of the antenna is fabricated and measured. Measured results show that the antenna's impedance bandwidth is 450 (18%), 350 (10%), 1200 (21.8%) MHz at the three resonant frequency points (2.5 GHz, 3.5 GHz, 5.5 GHz) with mutual coupling between the antenna elements less than �18 dB in whole frequency band, making this antenna a good candidate for portable application.

A compact coplanar waveguide-fed tri-band monopole antenna for WLAN/WiMAX applications is proposed. By employing a pair of inverted-L slots etched on the ground plane and a split-ring resonator (SRR) and further carefully adjusting the lengths and positions of these structures, two notched bands can be obtained. Measured results show that a tri-band of 280MHz (2.28–2.56 GHz), 920MHz (3.29–4.21 GHz), and 860MHz (5.05–5.91 GHz) with reflection coefficient less than −10 dB is obtained covering all the 2.4/5.2/5.8 GHz WLAN bands and 3.5/5.5 GHz WiMAX bands. In addition, good dipole-like radiation characteristics over the required bands is achieved in both Eand H-planes.

Stepped impedance resonator (SIR) and asymmetric coupled-line sections are used to design a novel fifth-order wideband bandpass filter in this paper. Even- and odd-mode technique is introduced to design and analyze the filter. The proposed filter possesses the characteristics of spurious-free response up to the third harmonic frequency with two transmission zeros on each side of the passband, thus resulting in the improved selectivity. One prototype with 3-dB fractional bandwidth of 53% (2.2–3.79 GHz) is fabricated for demonstration, and good agreement can be observed between simulated and measured results.

A wideband planar printed quasi-Yagi antenna with band-notched characteristic is presented. The proposed antenna consists of a microstrip-to-slotline transition structure, a gradient driver dipole, and two parasitic strips as directors. Meanwhile, the arms of the driver and two directors are rotated in a certain angle to improve the gain. To avoid the frequency interference from WLAN operating in the frequency band from 5.15 GHz to 5.825 GHz, an L-shape slot etched on the driver dipole is adopted to achieve a notched band ranging from 4.8 GHz to 6.1 GHz. The ground plane is symmetrically added two stubs to implement the lateral size reduction. The measured bandwidth, determined by the reflection coefficient less than −10 dB, covers from 3 GHz to 10.8 GHz. Better than 8.1 dB F/B ratio and the measured antenna gain varying between 4.7 and 8.3 dBi are also achieved in the operating bandwidth excepting in the notched band.

A broadband CPW-fed circularly polarized square slot antenna for ultra-high-frequency (UHF) radio frequency identiflcation (RFID) applications is proposed. It consists of a square slot embedded with a spur line along diagonal and an F-shaped feeding structure. The proposed antenna achieves an impedance bandwidth about 307MHz (34.6% @886MHz) and a 3dB axial ratio (AR) bandwidth about 232MHz (24.3% @954MHz). The 3dB AR beam-width is about 96 degrees over the UHF band of 840{960MHz. The proposed reader antenna based on CPW structure is easy to integrate. With the symmetry and bidirectional radiation pattern, there are less readers needed in some applications, such as access control, than the reader with unidirectional pattern, which will deflnitely decrease the implemented cost. Therefore, this universal design with desired performance across the entire UHF RFID band (from 840MHz to 960MHz) can be applied to all the UHF RFID applications worldwide. Detailed considerations of the design and main parameters will be studied in this paper.

A closely spaced dual-band notched UWB MIMO antenna is proposed in this paper. A traditional semi-circular monopole with ultra-wideband operation is chosen as an element of the proposed MIMO antenna. When two of the UWB monopoles are put together closely, the mutual coupling between them is apparently strong. To reduce the coupling between the antenna elements, a T-shaped branch is inserted between them, which reduces the mutual coupling obviously over the entire operating band. Also, the T-shaped branch can perform as a compensating radiator which can lower the operating frequencies of the proposed antenna. In order to achieve dual band-notched characteristics, meandering slots are cut in the patches, and symmetrical C-shape strips are nearly placed to the monopoles' feed-lines. The meandering slot is for lower band notch (WiMAX, 3.3{3.7GHz) while the C-shape strips are for upper band (WLAN, 5.15{5.825GHz). The measured radiation e-ciencies, peak gains and radiation patterns are illustrated and show good agreement as anticipated.

A novel compact UWB antenna with 3.5/5.5GHz dual notch-band characteristics is presented. The proposed antenna has a simple structure and compact size of 30 £ 35mm 2 . Firstly, a compact modifled rotated monopole antenna that covers UWB band is achieved. Then by inserting a ‚/4 stub and etching two symmetrical ‚/4 L-shape slots on the UWB antenna achieved before, a dual band-notched ultra-wideband antenna is obtained. The prototypes of UWB antenna with and without notched bands were fabricated and measured. Good performance of dual notched bands, stable gain and omnidirectional radiation patterns make the proposed antenna promising for UWB application.

Equilateral-triangular slot antennas with modifled edges for wideband circular polarization are proposed in this paper. Circular polarization was flrstly obtained by adding two asymmetric perturbations to two edges of triangular slot. Then fractal-like boundaries were adopted in the antenna design for size reduction and broadband operation. Two antenna prototypes for RFID readers were fabricated to cover RFID UHF band and ISM 2.4GHz band, respectively. Measured results show that the presented antennas obtain fairly wide 3-dB axial ratio bandwidths of 15.7% (820{960MHz) and 19.8% (2.18{2.66GHz).

A novel broadband planar rotated cross monopole antenna, which consists of a vertical patch (area A) and a rotated horizontal patch (area B), is proposed. By rotating the horizontal patch, the bandwidth of the proposed antenna can be signiflcantly enhanced. The efiect of the rotated angle of the horizontal patch on the bandwidth has been deeply studied. The measured results show that the proposed antenna with compact size of 50 £ 50mm 2 can achieve a wide impedance bandwidth (10-dB re∞ection coe-cient) as large as 8.76GHz (2.33{11.09GHz) or about 130%, which is nearly two times of what the corresponding conventional cross monopole antenna was.

A compact multiple-input-multiple-output (MIMO) antenna that covers the WLAN (2.4GHz) and UWB (3.1{10.6GHz) bands for wireless device applications is presented. The proposed antenna consists of two open L-shaped slot (LS) antenna elements and a narrow slot on the ground plane. The antenna elements are placed perpendicularly to each other to obtain a high isolation, and the narrow slot is added to reduce the mutual coupling between antenna elements at the WLAN band (2.4GHz). The presented MIMO antenna has a small size of 40£40mm 2 , and the prototypes of antenna is fabricated and measured. The measured results show that the antenna has an impedance bandwidth of larger than 2.4{10.6GHz with the mutual coupling less than 20dB in WLAN band and 18dB in 3.1{10.6GHz, making the antenna a good candidate for portable applications.

A dual circularly polarized (CP) antenna is proposed in this paper. By employing suspended strip line to feed the patch at the two diagonal positions with 90 ◦ phase difference, single circular polarization is firstly obtained. Then dual circular polarization is excited by an L-shaped strip. The two feeding ports near the edges of the L-shaped strip arms provide the conversion between left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP). Measured results show that the proposed antenna has 10-dB return loss bandwidth of 30.5% (2.08-2.83 GHz), 10-dB isolation bandwidth of 15.7% (2.29-2.68 GHz), 3-dB axial ratio (AR) bandwidth of 25.1% (2.16-2.78 GHz).

This study proposes a difierential-fed microstrip antenna, which is characterized with an ultra-wideband of 120% (3{12GHz), improved radiation patterns, stable gains, and compact size. Two symmetrical trapezoid shaped slots and four triangle-cut corners on the ground are used to improve the impedance matching over the UWB frequency band. To clarify the improved radiation characteristics, the simulated radiation patterns of the proposed antenna are compared with the conventional single- ended feed UWB antennas. The measured results show that, in the entire frequency band, the designed antenna exhibits a stable radiation patterns and the gain variation is less than 2dB. Furthermore, the polarization purity are increased compared with the conventional ones, especially in the high frequency band.

A novel wideband bandpass filter (BPF) based on signal-interaction concepts is presented in this paper. Two transmission paths with a wideband double-sided parallel-strip line 180° inverter and a 3λ/4 transmission line are employed to transmit signals from Port 1 to Port 2. By introducing two λ/4 shorted lines, the passband transmission performance of the BPF can be improved effectively. The experimental results demonstrate that the proposed BPF can achieve three transmission zeros and good harmonic suppression in the whole operating band ranging from 1.35 to 3.41 GHz, with 3-dB fractional bandwidth of 86%.

A simple wideband antenna with parasitic element is proposed in this paper. The printed antenna is comprised of an L-shape monopole and a parasitic element. By optimizing geometrical parameters of the parasitic element structure, a good impedance bandwidth which covers DVB (470MHz»702MHz) for return loss being higher than 5dB and LTE/700 (704MHz»787MHz), GSM850/900 (824MHz»894MHz/880MHz»960MHz) for return loss being higher than 10dB is achieved. The protype of the antenna is in size of 150mm £ 56mm. The measured and simulated e-ciency, gain and radiation pattern which is quasi omni-directional in the yoz plane make it to be a good candidate of mobile communicational terminals.

In this paper, a novel miniaturized branch-line coupler (BLC) operating at 1.675GHz is proposed. Partially meandered lines and dual transmission lines equivalent technology are used as the coupler's shunt arms, producing signiflcant reduction by more than 68% compared with the conventional coupler. Moreover, the coupler can equally divide the input signal with 90 - phase of difierence while maintaining the initial power from the source with a simple structure. The simulated and measured results are in good agreement, thereby verifying the design concept.

In this study, a novel dual band-notched ultra-wideband (UWB) antenna has been proposed and discussed. The proposed antenna is fed by a micro-strip line and in the square-etched radiation patch a T-shape parasitic stub is attached. On the other hand, a pair of parasitic parallel micro-strip lines are also added on the ground plane, one of which is shorted to the radiation patch by a short-pin through dielectric substrate. The two parasitic units are to achieve band- notched characteristics at 3.3{3.7GHz and 5.15{5.85GHz, respectively. In order to realize impedance matching over the ultra-wideband, two arc-shape cuts are made symmetrically at the junction of feed-line and radiation patch. The simulated and measured results, including return loss, radiation pattern, group-delay and peak gains are in good agreement with theory analysis which validates our design concept.

Square slot antennas with modifled edges for broadband circular polarization are presented. Slots with only stubs or notches are studied and it is found that the axial ratio (AR) bandwidth is quite sensitive to the perturbations of the stubs and notches. To further enhance the AR bandwidth, slot antennas with combination of stubs and notches are proposed and wide 3-dB AR bandwidth of 15.5% (2.45{2.86GHz) is obtained. By placing a conducting re∞ector at the rear of the slot, another modifled square slot antenna is designed for practical applications, which achieves a 3-dB AR bandwidth of 6.5% (2.38{2.54GHz) and peak gain of 8.7dBic. Agreement between simulated and measured results is satisfactory.

A novel inductively loaded monopole for future ultra-wide- band (UWB) applications is presented. The antenna is compact and of small size (16mm £ 20mm £ 0:8mm), and ofier a very simple geometry suitable for low cost fabrication and straight forward printed circuit board integration. More speciflcally, the impedance matching of the classic printed inductively loaded monopole is improved by employment of the tapered microstrip feed line between K-connector and the printed monopole. By using this technique, impedance bandwidth (S11 < i10dB) from 3.03GHz to over 40GHz is obtained. Measured and simulated return loss curves are provided along with radiation patterns and gains, as a function of frequency. Compared to the recently reported UWB antennas, the presented antenna have smallest size, widest bandwidth, and simple conflguration to realize the application in UWB communication systems. Furthermore, symmetric radiation patterns and satisfactory gains make the presented antenna a suitable candidate for practical UWB applications.

A novel compact dual band-notched ultra-wide band antenna with hexagonal slotted ground is proposed. By inserting two pairs of L-shaped branches symmetrically into the slotted ground plane, two notched bands, 3.3–3.7 GHz for worldwide interoperability for microwave access and 5.15–5.825 GHz for wireless local area network, are achieved, respectively. A prototype of the proposed antenna is designed, fabricated, and tested. By optimizing the length of the L-shaped branches and the gap between them, the desired bandwidth of VSWR (voltage standing wave ratio) less than 2.0 can be achieved, ranging from 2.5 to 11 GHz, except two stop-bands of 3.1–4.0 and 5.0–6.0 GHz. The simulated and measured results of the proposed antenna have shown a reasonable agreement between them. The proposed antenna has a compact size, ultra wide bandwidth, good radiation characteristics, and good time-domain behaviors. It is very suitable for modern wireless communication applications.

A novel dual-band dual-polarized antenna design with high isolation and low cross-polarization is presented. An arc-coupled annular ring and a special coaxial-fed slot patch are employed as the radiating elements at lower and upper bands, respectively. Measurements show that the 10-dB impedance bandwidths reach 27.9% (1.66–2.19 GHz) and 18.4% (5.09–6.12 GHz). The port isolation for both bands is better than 30 dB. Moreover, stable and symmetrical radiation patterns at slanted polarizations are achieved, and the measured cross-polarization level is less than dB within the above-mentioned bands.

A novel coaxial-feed dual-polarized slot antenna with high isolation and low cross-polarization is presented. Special slots are employed for symmetrical radiation patterns at slanted polarization and low cross-polarization under dB, which include two pairs of T-shaped slots and two pairs of cross-shaped slots in the radial directions of a circle patch. Moreover, high isolation of more than 36 dB between the two feeding ports is achieved by introducing two shorting pins. The experimental results demonstrate the proposed antenna is capable to operate over the frequency range of 2.23–2.91 GHz, suitable as the base station antenna for WiMAX applications.

The design of a novel printed dipole antenna with bandwidth enhancement is proposed for wideband applications. The antenna consists of an integrated balun, two rectangular radiating arms and a modified inductive coplanar stripline (CPS) impedance tuner. By adjusting the parameters of the CPS-tuner and the balun properly, a good performance of bandwidth enhancement is achieved. The measured results indicate that the impedance bandwidth of the proposed antenna, defined by 10-dB return loss, is about 73.9% from 2.54 to 5.52GHz. In addition, good omnidirectional radiation characteristics are also obtained over the whole operating band. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1585–1590, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26883

A novel multiband rhombic slot antenna with a truncated corner is proposed for wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications simultaneously. By introducing a pair of straight strips and two etched ∩-shaped slots, the proposed antenna can operate in multibands. The prototype of the proposed antenna has been successfully constructed and tested. The 10 dB return loss bandwidths of them are 550 MHz (3.15–3.70 GHz) and 920 MHz (5.05–5.97 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). In addition, good monopole-like radiation characteristics with sufficient antenna gains are obtained over the operating bands. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1466–1469, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26837

In this article, a novel compact UWB antenna with dual band-notched characteristics is proposed. The original UWB antenna is realized by etching an open-slot on the ground plane. The 5.2- and 5.8-GHz WLAN rejected bands are achieved by inserting a slot on the ground plane and a slot-type split ring resonator inside a circular exciting stub on the front side, respectively. The antenna has a compact structure with an area of 16 × 27 mm2. The small size makes it an excellent candidate for UWB operation. Prototype of the antenna are fabricated and tested. The simulated and measured results show that the proposed antenna achieves a wide impedance bandwidth (VSWR 2) are 4.85–5.37 GHz and 5.68-5.98 GHz. Radiation patterns and antenna gains are also given in this article. Detailed design steps, parametric studies and experimental results for the antenna are investigated in the following section. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1159–1163, 2012

A novel microstrip-fed ultrawideband elliptical antenna with dual band-notched characteristics is proposed and fabricated. Dual band-notched characteristics are achieved by a defected ground structure and using a tuning stub embedded in the microstrip feed line. The operation bandwidth of the designed antenna is from 2.6 to 12 GHz for voltage standing wave ratio less than 2, except two frequency notched bands of 3.2–4.1 GHz for WiMAX and 4.9–6.0 GHz for wireless local area network. Moreover, the proposed antenna provides a good radiation pattern and a relatively flat gain over the entire frequency band excluding the rejected bands. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:780–783, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26625

In this paper, an electromagnetic band-gap (EBG) structure is proposed to achieve tri-band operation for a novel circular slot patch antenna, which is suitable for WLAN and WiMAX applications. The proposed antenna consists of a rectangular radiation patch with an etched circular slot, a circular ring, and a mushroom-like EBG structure, all of which are printed on the top side of the substrate. By embedding a circular ring in the circular slot, the antenna can generate two impedance bandwidths. With the use of EBG structure, the proposed antenna can operate in three separate bands. Simulation results are compared with the measurements, and a good agreement is obtained. The measured results show that the 10 dB return loss bandwidths of the proposed antenna are 530 MHz (2.28–2.81 GHz), 470 MHz (3.29–3.76 GHz) and 1250 MHz (4.87–6.12 GHz), which can cover all the 2.4/5.2/5.8 GHz WLAN bands and 2.5/3.5/5.5 GHz WiMAX bands. In addition, a design evolution and a parametric study of the proposed antenna are prese...

A printed microstrip-line-fed slot antenna with a pair of parasitic patches for bandwidth enhancement is proposed in this letter. By using the parasitic patches along the microstrip feed line, an additional resonance is excited, and a good performance of bandwidth enhancement can be obtained. The proposed antenna is designed and manufactured successfully. The measurement shows a good agreement with the simulation. From the measured results, the enhanced impedance bandwidth, defined by voltage standing wave ratio (VSWR) less than 2, is about 136% ranging from 2.1 to 11.1 GHz. In addition, stable and nearly omnidirectional far-field radiation patterns are observed over the entire operating band.

This article presents a compact multiband planar inverted-F antenna design for mobile phone applications. The proposed antenna comprises dual twisted lines, a shorting strip and an L-shaped coupling strip. The dual twisted lines are excited by the coupling strip to generate four resonance modes around 900, 1800, 2100, and 3500 MHz and covers six bands including the global system for mobile communication 850/900 (824–894 MHz), (880–960 MHz), digital communication system (1710–1880 MHz), personal communication system (1850–1990 MHz) universal mobile telecommunication system (1920–2170 MHz) and worldwide interoperability for microwave access (3400–3600 MHz). The antenna shows a planar structure and occupies a very small-size of 15 × 26 mm2, making it especially suit for mobile phone applications. This research performed simulation by high frequency structure simulation and CST to design and analyze the antenna, and a practical structure was fabricated and tested. The measured and simulated return loss show good agreement. Moreover, the radiation patterns and the specific absorption rate are discussed too. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:1233–1236, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25996