Metamaterial superstrate-loaded meandered microstrip-based radiating structure for bandwidth enhancement

We have introduced metamaterial superstrate in microstrip-based radiating structure to increase its bandwidth. Split ring resonators are added as metamaterial metallic inclusion in superstrate of the conventional design. This changes the basic structure of the material. Material properties such as permittivity and permeability changed due to change in the structure. The change in its material properties enhances the bandwidth of the antenna. The antenna is meandered to achieve better performance at the edges which in a way improve the radiation path of the patch. Here, the proposed antenna works on three bands in the range 3–8?GHz. Maximum 60% bandwidth is enhanced in the third band. The voltage standing wave ratio and return loss (S₁₁) of the entire three bands are shown in the paper. The antenna works on 3.51, 4.86 and 7.8?GHz. Design results are obtained by high-frequency structure simulator which is used for simulating microwave passive components.     

Compact bandpass filter based on two meandered parallel-coupled lines in different lengths

A new compact bandpass filter based on two meandered parallel-coupled lines of different lengths in shunt is presented, using the signal-interference technique, this filter obtains a low insertion loss and sharp rejection. A set of analytical formulas and guidelines for the design of the bandpass filter are provided in two theoretical analysis methods. According to the number of attenuation poles of the reflection coefficients in the passband, it can be summed up two types of filters. To validated this topology, two wideband bandpass filters centered at 3 GHz are built to verify the theoretical prediction, the measured frequency response of the filter agrees excellently with the predicted result.     

A uniplanar printed antenna with an inverted L‐shaped coupling feed for LTE/GSM/DCS/PCS/UMTS operations

A novel uniplanar printed antenna with a total size of 115 × 40 mm² is proposed for mobile device application. By using an inverted L‐shaped feeding mechanism and a meandered shorting strip, a dual‐band operation with wideband characteristic can be achieved. Here, the lower operating band is able to cover the LTE 700 and GSM 850/900 operations, while the higher operating band allows DCS 1800, PCS 1900, UMTS, and LTE 2300 operations. Furthermore, in order to increase the bandwidth of the higher operating band so that LTE 2500 operation can also be covered, an additional parasitic stub is attached to the feed line to excite a resonant frequency at around 2.72 GHz. Parametric studies via simulation are carried out, and prototype of the proposed antenna is also experimentally investigated to validate the simulated results. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2012.     

Modeling and design of printed antennas using neural networks

A single neural network is developed to model the resonant frequency of rectangular patch printed on uniaxially anisotropic substrate with air gap using effective parameters in conjunction with spectral dyadic Green's function. Also, the strength of ANN models in antenna design is demonstrated by considering two case studies: the design of circular patch antenna and planar inverted‐F antenna. Results show good agreement with literature. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011.     

Multiband Meandered Monopole Antenna for Mobile Applications

A multiband meandered monopole antenna is proposed for digital video broadcasting handheld (DVB‐H), global positioning system, personal communications service, wireless broadband (Wibro), and wireless local area network (WLAN) applications. The proposed antenna consists of a meandered line, a shorted length strip line, and a conductor strip between a meandered line and a microstrip feed line. By tuning a short strip and a conductor, a multiband impedance matching is achieved. The proposed antenna has an omnidirectional radiation and yields an antenna gain of greater than ?3 dBi in the DVB‐H band and 4.5 dBi in the Wibro and WLAN bands. Details of the proposed antenna design and experimental results are presented.     

一种超高频射频识别读写器天线

本文提出了一种适用于我国UHF RFID读写器的宽带圆极化叠层微带天线,通过选用廉价FR4板、空气层介质和对角线切角的正方形贴片组成叠层结构,采用S型水平蜿蜒带条激励主辐射贴片的馈电方式,展宽了天线的阻抗带宽和轴比带宽.所提出的S型水平蜿蜒带条馈电技术,实现了对称的辐射方向性图.给出了天线设计思路,并利用电磁仿真软件分...     

多频段背腔式半模基片集成波导弯折缝隙天线

针对需要安装在金属平台上的天线应用,提出了一种具有定向辐射特性的新型多频段背腔式半模基片集成波导缝隙天线。利用半模基片集成波导谐振腔的多模式特性实现了该天线多频段工作,通过在谐振腔的金属顶面蚀刻弯折形状的缝隙实现对外辐射,并可以通过调整弯折缝隙尺寸参数来减小天线尺寸。仿真和测试结果表明,该天线能同时工作在5.7/10.7/11.9/12.5/13.1GHz,且在这5个频段的最低增益大于6.7 dBi。天线具有便于和平面电路集成、体积小、结构简单、成本低等优点,具有一定的工程应用价值。     

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.     

Miniaturized frequency-selective surface with reduced number of metallic vias for electromagnetic shielding

A miniaturized frequency-selective surface (FSS) for radio frequency (RF) filtering applications is reported in this paper. The proposed FSS is designed to operate with band stop property at 1.57 GHz. The FSS element is developed using highly convoluted lines running on either side of the substrate interconnected using via lines. This specific arrangement increases the electrical length of the resonator without increasing the physical size. Furthermore, the stability towards polarization variation and independence to different angles of incidence are other major concerns in the design of FSS. The FSS unit cell has rotational symmetry thereby providing polarization-independent operation. The angular independence is tested for various incidence angles, and the results are presented. The performance of the FSS is validated in real time, and the results are presented. The maximum realized transmission loss is 27 dB at 1.57 GHz, and the attenuation bandwidth with reference 10 dB shielding level is estimated to be 400 MHz centered around 1.57 GHz. The convolution technique along with shorting vias has offered this extreme miniaturization ranging from 7% to 95.7% with reference to most of the FSS reported for L-band services such as radio, telecommunications, military, and aircraft surveillance.