A frequency reconfigurable antenna for multiband mobile handset applications

A frequency‐reconfigurable antenna is presented for multiband (GSM850/900/GLONASS1616/DCS1800/PCS 1900/UMTS/LTE2300/2500/WLAN) mobile handset applications. It mainly consists of radiating elements with two PIN diodes. By switching the ON/OFF states of the PIN diodes, the proposed structure can operate in three states: OFF–ON, ON–OFF, and ON–ON. When PIN diodes are in the OFF–ON states, the proposed antenna can cover the GSM850/900, PCS1900, and UMTS2100 bands by operating in Invented‐F antenna (IFA) mode. When PIN diodes are in the ON–OFF states, the antenna can cover the LTE2300/2500 and WLAN2400 bands in monopole mode. Moreover, when PIN diodes are switched to the ON–ON states, the designed antenna works in loop mode and its resonant frequencies include the GLONASS1616, DCS1800/1900, and LTE2500 bands. With the reconfigurable technique, the proposed antenna achieves a compact size of 15 × 28.5 mm² with high efficiency from 34% to 84.86% in the total frequency range.     

A multi‐mode wideband omnidirectional monopolar patch antenna for indoor wireless communication systems

A wideband omnidirectional monopolar patch antenna merged multi‐mode with a simple structure is proposed in this article. The antenna consists of a circular patch and a concentric annular ring, which is coupled‐fed by a T‐shape monopole at its center. A wideband performance is achieved by converging multi‐mode: TM₀₂ mode of the circular patch, TM₀₂ mode of the annular ring and monopole mode of the T‐shape monopole. The measured results show that the proposed antenna has an impedance bandwidth of 55.3% from 4.45GHz to 7.85GHz. All of the three resonant modes lead to conical radiation patterns in the elevation plane and omnidirectional radiation patterns in the azimuth plane, and the measured peak gain varies from 6.1 to 10 dBi within the operating band, which verifies it can be a good choice for indoor wireless communication systems.     

Planar UWB antenna with modified slotted ground plane

A compact coplanar waveguide‐fed (CPW) monopole antenna for ultra‐wideband wireless communication is presented. The proposed antenna comprises of a CPW‐fed beveled rectangular patch with a modified slotted ground. The overall size of the antenna is 30 mm × 27 mm × 1.6 mm. The lower edge of the band is attained by properly decoupling the resonant frequencies due to the extended ground plane and the beveled rectangular patch of the antenna. The upper edge of the radiating band is enhanced by beveling the ground plane corners near the feed point. Experimental results show that the designed antenna operates in the 2.7–12 GHz band, for S₁₁ ≤ ?10 dB with a gain of 2.7–5 dBi. Both the frequency domain and time domain characteristics of the antenna are investigated using antenna transfer function. It is observed that the antenna exhibits identical radiation patterns and reasonable transient characteristics over the entire operating band. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2012.     

Multiband antenna for mobile terminals

In this paper, a multiband antenna composed of a tri‐mode monopole, an open‐slot etched on the ground, and a parasitic strip is proposed for mobile terminals. The tri‐mode monopole excites three modes including 0.25 λ, 0.25 λ, and 0.75 λ modes at 0.9, 1.85, and 2.4 GHz respectively, and can cover the desired frequency band 1.7 to 2.7 GHz. The open slot etched on the ground can obtain better impedance matching at 0.9 GHz to cover 0.82 to 0.96 GHz. To further broaden the bandwidth of the low frequency, a parasitic open‐ended strip is used to introduce a new resonance to extend the lower frequency band to 0.69 GHz. The proposed antenna is simulated, fabricated and measured. The impedance bandwidths with S₁₁ better than ?6 dB are 270 MHz (0.69‐0.96 GHz) and 1.06 GHz (1.7‐2.76 GHz). The consistency between the measured and simulated results indicates that the proposed antenna is available for mobile phone applications.     

A dual feed PIN diode based switchable multiband planar meandered antenna for intelligent transportation system application

This article presents a dual feed switchable coplanar linearly polarized multiband meandered microstrip patch antenna. The antenna provides multiband functionalities with switching allowable at one of the nine adjacent frequencies. The proposed antenna, loaded with two symmetric PIN diodes, comprises dual‐patch configuration and excited by coplanar microstrip feeds, it operates within 1 to 15 GHz frequency bands. The induced current of the antenna can be changed by switching the diodes, resulting in different operating frequency bands. The antenna has a nearly broadside radiation pattern and the impedance bandwidth is obtained up to 47% having a center frequency of 2.4 GHz for band range of 1 to 15 GHz. The measured gain of the antenna for 1.57, 2.4, 4.5, 4.71, 5.9, 6.53, 7.59, 10.8, and 11.87 GHz are 5, 5, 7, 6, 6.1, 4.4, 3.8, 3.5, and 1.87 dBi, respectively. The antenna has advantages of the simple biasing network, easy fabrication, and adjustment. It is suitable for many modern wireless communication systems like intelligent transportation system. This antenna is also useful in direct broadcast satellite applications.     

A miniaturized ultra‐wideband planar monopole antenna with L‐shaped ground plane stubs

This article presents a miniaturized ultra‐wideband planar monopole antenna with an oval radiator. The proposed antenna is fed by a coplanar waveguide (CPW), and two L‐shaped stubs are extended from the ground plane of the CPW. This presented antenna is able to produce resonances in the lower frequency band and realize better impedance matching performance in the middle and higher frequency bands with the aid of the L‐shaped stubs. The antenna was built and tested. The total size of the proposed antenna is only 26 × 20 × 1.6 mm³. Its measured –10 dB impedance bandwidth is 10.1 GHz (3.1‐13.2 GHz). The measured far‐field radiation patterns are stable in the whole operating frequency band.     

Bandwidth and gain improvements of low‐profile H‐shaped microstrip patch antenna under quadruple‐mode resonance

A wideband low profile H‐shaped microstrip patch antenna (MPA) with reallocated quadruple‐mode resonance is presented for indoor wireless communication application. In this paper, the TM₂₀ (mode 1), TM₀₂ (mode 2), TM₂₂ (mode 3), and additionally notch mode 4 of the proposed MPA are simultaneously employed. First, the rectangular radiating patch is reshaped as an H‐shaped radiator so as to separate a pair of degenerate modes (mode 1 and mode 2). Then, a pair of linear notches is cut on the diagonal of the patch to excite an additional notch resonance (mode 4). Finally, in order to improve the frequency of mode 1, four shorting pins are placed at the four corners of the H‐shaped patch. Therefore, the bandwidth of the antenna is dramatically increased up by utilizing four resonant modes (modes 1, 2, 3, and 4). A prototype of H‐shaped patch antenna with notches and shorting pins is manufactured and measured. The results show that the antenna achieves a broad bandwidth of about 31.7% (2.31‐3.18 GHz), and its profile is only 0.036 wavelength of center frequency. It is particularly noticed that a relative high gain of around 9.8 dBi is successfully acquired, while keeping relative stable dual‐beam radiation patterns.     

A novel wideband circularly polarized modified square‐slot antenna with loaded strips

In this article, a novel inverted L‐shaped microstrip‐fed wideband circularly polarized (CP) modified square‐slot antenna is designed. By cutting a pair of triangle chamfers and introducing a pair of triangle patches at the square‐slot, the antenna achieves a wideband CP radiation. Moreover, CP performance of the antenna can also be remarkably enhanced by protruding an L‐shaped strip and embedding a tuning rectangle slot into the slot ground. The measured results demonstrate that the axial‐ratio bandwidth for AR < 3 is 75.1% (from 4.45 to 9.8 GHz) and the impedance bandwidth (|S₁₁| < ?10 dB) reaches 65.8% (from 4.95 to 9.8 GHz). In addition, surface current studies are performed to illustrate the operating mechanism of CP operation, and the antenna has bidirectional radiation characteristics with an average gain of ~4 dBic within the CP band.     

Multiband,miniaturized, maze shaped antenna with an air‐gap for wireless applications

A novel maze shaped multiband monopole antenna with a miniaturized size of only 6 × 4 × 1.6 mm³ is proposed. To further achieving excellent radiation performances across the desired operating bands, an air‐gap is set between the proposed antenna and system ground. To assess the performances of the antenna, simulations are initially carried out by loading a 1.6 mm thick nonconducting Polycarbonate material (analogous to an air‐gap) between the antenna and system ground, and a simplified equivalent circuit (EC) model of the proposed antenna is also derived. The proposed antenna has excited two different resonance frequencies, in which the lower band (f_L) and upper band (f_U) can yield broad 10‐dB impedance bandwidths of 6.5% (2.37‐2.53 GHz) and 16% (5.05‐5.90 GHz), respectively. Furthermore, desirable gain and radiation efficiency of 2.85 to 6.40 dBi and 57% to 85%, respectively across the two operating bands were also achieved. A practical experiment is also carried out by installing the proposed antenna into a real laptop computer (L412 Think Pad Lenovo).     

正方形嵌套分形多频印刷对称振子天线

设计了一类具有正方形嵌套结构的新型分形多频对称振子天线.振子由一系列相似的正方形单元嵌套组成.天线能够同时工作于多个频率,这些频率涵盖了WLAN系统所要求的2.4 GHz/5.2 GHz/5.8 GHz三个频率,采用三维电磁仿真软件CST MWS(R)软件进行了仿真研究,得到了平衡微带线馈电的对称振子天线的模型.制作了...     

A wideband rectifier array on dual‐polarized differential‐feed fractal slotted ground antenna for RF energy harvesting

This article reports a novel wideband rectenna for RF energy harvesting applications. A wideband fractal slotted ground antenna (SGA) is adopted. The operating frequency bands of the antenna are GSM, UMTS, Wi‐Fi, and LTE2600/4G bands. The antenna is fed by a dual‐polarized and differential‐feed (DP‐DF) microstrip lines disposed with an angle of 90° each relative to the other. The feed lines are etched on the bottom side of the substrate and connected to an array of four wideband RF‐to‐DC rectifiers. A nonuniform transmission lines filter ensures wideband behavior for each rectifier. The rectenna performances are simulated and measured. The experiments show an output DC voltage of 1 V at a power density of 26.6 μW/cm² over the frequency band of operation with a peak efficiency of 50%. The proposed rectenna is suitable for energy harvesting applications in urban environments.     

Wideband and compact horizontally polarized omnidirectional antenna using composite dipole elements

A wideband horizontally polarized (HP) omnidirectional antenna is constructed and experimented in this article. The antenna consists of four composite dipoles forming a circular array in the azimuth plane and four pairs of parallel strip lines as impedance transformer networks. Two kinds of dipoles compose the composite dipole to achieve a wideband operation. By utilizing the composite dipole, four resonances can be simultaneously excited and manipulated to increase the bandwidth. A prototype is manufactured to validate the method. The dimensions of the antenna are just 0.62λ₀ × 0.62λ₀ × 0.03λ₀ (λ₀ is the free‐space wavelength at center frequency). The measured results show that the presented antenna has a impedance bandwidth of 58.6% (1.63–2.98 GHz) for VSWR ≤2. The gain variations are less than 0.6 dB at the azimuth plane in the operating band. Meanwhile, the cross‐polarization is less than 20 dB and the peak gain reaches 1.7 dBi among in the band. These advantages of the antenna make it suitable for 4G mobile communication applications.     

Electrically coupled dual semicylindrical dielectric resonator antenna with inverted arrangement for wideband applications

In this article, an electrically coupled dual semicylindrical dielectric resonator antenna (SC‐DRA) is presented and discussed for wideband applications. The two SC‐DRAs are placed in an inverted arrangement and fed by a coaxial probe to excite the fundamental mode TM _11δ and higher order mode TM _21δ. In the proposed design, wideband performance is obtained by combining the fundamental and higher order mode. Proposed wideband antenna is showing simulated and measured input impedance bandwidth (|S₁₁| ≤ ?10 dB) of 57.94% (3.8‐6.9 GHz) and 64.4% (3.38‐6.6 GHz), respectively. The far field radiation patterns are found to be consistent and 3‐dB beamwidth of 49° and 30° has been achieved at 4.11 and 6.48 GHz, respectively within the working band. This design attains an average gain of 5.65 dBi and radiation efficiency of 97%, respectively.     

Miniaturized low‐profile antenna based on uniplanar quasi‐composite right/left‐handed metamaterial

In this article, a metamaterial‐based broadband low‐profile antenna is presented. The proposed antenna employed an array of uniplanar quasi‐composite right/left‐hand (CRLH) metamaterial cells. This structure contributes to exciting the operating modes in lower frequencies. The antenna has an overall electrical size of 0.75 × 0.60 × 0.07 λ₀³ (λ₀ is the center operating wavelength in free space) and provides a 25% measured bandwidth with the center frequency of 5.1 GHz and maximum gain of 6.6 dB. The proposed antenna is an appropriate candidate for WLAN, WiMAX, and other wireless communication applications.     

A metamaterial hepta‐band antenna for wireless applications with specific absorption rate reduction

Present article embodies the design and analysis of slotted circular shape metamaterial loaded multiband antenna for wireless applications with declination of SAR. The electrical dimension is 0.260 λ × 0.253 λ × 0.0059 λ (35 × 34 × 0.8 mm³) of proposed design, at lower frequency of 2.23 GHz. The antenna consists of circular shape rectangular slot as the radiation element loaded with metamaterial split ring resonator (SRR) and two parallel rectangular stubs, etched rectangular single complementary split‐ring resonator (CSRR) and reclined T‐shaped slot as ground plane. Antenna achieves hepta bands for wireless standards WLAN (2.4/5.0/5.8 GHz), WiMAX (3.5 GHz), radio frequency identification (RFID) services (3.0 GHz), Upper X band (11.8 GHz—for space communication) and Lower K_U band (13.1 GHz—for satellite communication systems operating band). Stable radiation patterns are observed for the operating bands with low cross polarization. The SRR is responsible for creating an additional resonating mode for wireless application as well as provide the declination in SAR about 13.3%. Experimental characteristic of antenna shows close agreement with those obtained by simulation of the proposed antenna.     

A wideband frequency agile fork‐shaped microstrip patch antenna with nearly invariant radiation patterns

A wideband frequency agile fork‐shaped microstrip patch antenna is presented. Its operating frequency is tuned by incorporating four varactor diodes, which are placed symmetrically on the patch. The operating mechanism of this antenna is also briefly discussed. The full wave analysis simulated results show that the operating frequency can be tuned from 1.47GHz to 1.84GHz (frequency agility of 26.50%) with nearly invariant radiation patterns while achieving acceptable gain throughout the operating frequency range. Finally, the proposed fork‐shaped antenna was fabricated and measured for its impedance matching and gain radiation patterns. Measurement results show reasonable agreement with the simulated data. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:623–632, 2016.     

A high BDR microstrip‐line fed antenna with multiple asymmetric elliptical wide‐slots for wideband applications

In this study, a novel printed wide‐slot antenna for wideband applications is presented. The designed antenna consists of four merged elliptical wide‐slots (EWSs) of different dimensions in the ground plane. An open‐ended microstrip line having a characteristic impedance of 50 Ω is used to excite the EWS. Each EWS corresponds to the different frequency of operation and hence when merged together give a wideband response. The fabricated prototype of the designed antenna shows the 10 dB return loss bandwidth (RLBW) of about 157.72% ranging from 2.21 to 18.7 GHz. The peak gain varies from 0.1 to 6.5 dB within the RLBW is reported. An almost constant group delay, low variation (<?40 dB) in the transfer function S₂₁ and linear phase variation for both side by side and face to face orientations of the designed antenna shows its applicability for wideband applications. The electrical dimensions of about 0.176λ _L × 0.162λ _L (where λ _L is the lowest operating wavelength) give rise to the bandwidth dimension ratio of about 5505 which is highest among the antenna structures reported in the literature. The measured results are found in good concordance with the results obtained from numerical simulations.     

Compact tri‐band MIMO antenna based on quarter‐mode slotted substrate‐integrated‐waveguide cavity

A compact tri‐band multiple‐input‐multiple‐output (MIMO) antenna based on a quarter‐mode slotted substrate‐integrated‐waveguide (SIW) cavity is proposed. By etching a wide slot, a single SIW cavity is divided into two sub‐cavities with the same size. They are fed by coaxial ports to form two MIMO elements and high antenna isolation can be achieved by this slot. To obtain multi‐band operations, two narrow slots are cut in the upper sub‐cavity and the other two slots are etched in the lower sub‐cavity. Three eighth‐mode resonances with different areas can simultaneously occur in these antenna elements. A prototype with the overall size of 0.34λ₀ × 0.34λ₀ has been fabricated. The measured center frequencies of three operating bands are 2.31, 2.91, and 3.35 GHz, respectively. The measured gain at above frequencies is 4.52, 4.29, and 4.57 dBi, respectively. Moreover, the measured isolation is higher than 16.7 dB within the frequency of interest.     

Dielectric resonator array antenna for triple band WLAN applications with enhanced gain

An H‐shaped dielectric resonator array antenna is presented for wideband applications. The proposed antenna is excited by slot feed mechanism and investigated experimentally. The antenna covers the frequency ranges from 1.41 to 2.59 GHz, and 4.73 to 6.06 GHz with the corresponding impedance bandwidth of 59% and 24.65%, respectively. The simulation results fulfill the bandwidth requirements of IEEE 802.11a/b/g (2.4‐2.484 GHz/5.15‐5.35 GHz/5.725‐5.825 GHz) for Wireless local area network (WLAN) applications. The proposed antenna has simple structure, easy to fabricate and its measured radiation pattern shows a reliable performance in the desired operating bands.     

Design guidelines for single and dual wide band leaky periodic microstrip line antennas

Leaky wave antennas using periodic microstrip lines are natural choices for versatile beam scanning applications. In this work, a shorted stub and an open stub are simultaneously used in the same unit cell to generate resonant frequencies dependent on the stub dimensions. Placing one such resonant frequency at the second Bragg stop band, a single wideband response is obtained. Next, the stub lengths are tuned to obtain two resonant frequencies which are placed at the second and fourth Bragg stop bands, respectively to obtain a dual wideband response. Design guidelines are outlined for obtaining these wide bands and corresponding radiation regions. Two such geometries with single and dual‐band nature are fabricated. The single wide‐band antenna has a pass‐band from 5.89 to 11.57 GHz with a beam scanning range of ?56° to 33°. The dual‐band antenna has two pass‐bands radiating in the frequency range 5‐6.5 GHz and 10.7‐14.7 GHz. Beam scanning range in the first pass‐band is ?72° to ?5°. The second pass‐band, in part, demonstrates a dual‐beam nature with the forward beam scanning from 28.9° to 54.5° and backward beam scanning from ?54.5° to 14.76° as the frequency varies from 12 to 14.5 GHz.