Sudhakar Sahu

Design & development of UWB notch antenna with fractal geometry

This paper presents the design of coplanar waveguide fed ultra wide band Antenna with fractal geometry having frequency Notch characteristics. The designed antenna shows a dual band notch characteristic. For increasing bandwidth Sierpinski fractal is responsible, which is etched from the circular radiator. Elliptical type of slot responsible for creating notched band centered at 5.2 GHz for wireless local area network rejection has been used in this work. The RFID rejection band centered at 7 GHz is achieved by using a opposite U shaped fractal curve at feed line. Sierpinski fractal slot on the radiator has contributed to the resultant bandwidth of 1.8-11.5 GHz with VSWR<;2 by increasing the characteristics of matching at lower frequencies with an exception of two notched bands. A theoretical formulation to calculate the notch frequency is also validated.

Frequency reconfigurable antenna inspired by metamaterial for WLAN and WiMAX application

A frequency reconfigurable antenna inspired by metamaterial for WLAN and WiMAX application was presented. Two different antenna was proposed namely antenna (1) & antenna (2). Antenna (1) is designed to resonates at 5.2 GHz(WLAN Band) with impedance bandwidth 1.4407 GHz. The Antenna (2) is the extension of antenna (1). Two resonating particles in antenna (2) excited by dynamic magnetic field which produces negative permeability due to coupling with the monopole antenna; the whole structure is now a tri-band antenna. The antenna (2) sometimes produces tri-band resonates at 3.5 GHz (middle WiMAX) & 5.56 GHz(Upper WiMAX band), 4.65 GHz having overall bandwidth 1.9356 GHz, sometimes produces dual bands 3.5GHz and 5.3 GHz(WiMAX and WLAN band) having overall bandwidth 1.6445GHz, sometimes at single band 5.15GHz (WLAN band) having impedance bandwidth 1.4917 GHz. By introducing a single switch at each metamaterial cell, their effect can be deactivated and their corresponding resonance can be eliminated, and that results a frequency reconfigurable antenna. The job of unit omega cell only to shift center frequency of monopole 5.2GHz(WLAN band) to 5.56 GHz(Upper WiMAX band application).All structures had simulated using Finite Element Method(FEM) based on HFSS.

Compact circular patch antenna for SWB applications

This present literature gives the overall performance characterization of a simple circular patch antenna for SWB applications. The proposed design has an impedance bandwidth of about 26 GHz (2.4-28.4 GHz) with a very small size 30×40 mm2. The quarter wave transformer matching of the feed line enables the antenna operation over the wide band (169% fractional bandwidth). The introduction of a rectangular open ended slot in the ground plane enabled the mid-band impedance matching. The simple design, satisfactory gain, far field radiation pattern and group delay characteristics fulfils the requirements of the presented to be used for different applications involving SWB spectrum.

Design of compact UWB hexagonal monopole antenna with frequency notch characteristics

This paper presents the design of compact coplanar waveguide fed ultra wide band antenna having frequency Notch characteristics. The designed antenna shows a dual band notch characteristic. Hexagonal star type of fractal responsible for creating notched band centered at 5.2 GHz for WLAN elemination has been used in this work. In order to avoid interference with X-band uplink satellite communication system at 8.2 GHz, an opposite W shaped fractal curve at feed line has been used. Hexagonal monopole radiator has contributed to the resultant bandwidth of 3.1-11.2 GHz with VSWR<;2 by increasing the characteristics of matching at lower frequencies with an exception of two notched bands. A theoretical formulation to calculate the notch frequency is also validated.

Compact tapered fed dual-band monopole antenna for WLAN and WiMAX application

In this paper a compact tapered fed dual band monopole antenna based on complimentary split ring resonators(CSRR) used for WLAN and WiMAX application. Two CSRR are placed side by side symmetrically, which produces a narrow stop band in a single band for which dual band observed. As over all bandwidth reduces the gain is improved. The composite metamaterial CSRR can provide dual band operation at 1.9-2.6 and 2.92-4.3 GHz with reflection coefficient less than -10 dB by the two resonant modes due to CSRR and length of the patch. The gain at lower resonant band -2-0.2 dB and at higher resonant band 0.5-2 dB. A 50 Ω microstrip line, followed by parabolic feed and rectangle step feed is adopted for impedance matching. The uniqueness of this design is that the CSRR generates a narrow stop band in a wideband produced by an element without having any CSRR, which makes the dual band antenna very compact. Antenna parameters like reflection coefficient, radiation pattern, gain are analyzed with numerical simulation.

Compact microstrip fed UWB antenna with dual band notch characteristics

A compact microstrip fed ultra-wideband(UWB) antenna with dual band notched characteristics is presented. The antenna comprises of an elliptical UWB patch antenna with partial arc shaped ground plane fed by micro-strip transmission line. Two open-ended quarter-wavelength straight slots are etched in the patch to generate the two notched band. The UWB antenna covers a wide impedance bandwidth ranges from 2.86GHz-14.9Ghz with two band notched properties in the Wimax (3.1GHz-4.8GHz) X-band satellite link(9.6GHz-11.2GHz). The proposed antenna has a compact dimension of 32×38 mm2 and nearby stable radiation patterns are obtained in the operating band.

Concentric three-layer cylindrical DRA for UWB applications

Here a Ultra wide band Concentric 3-Layer cylindrical dielectric resonator antenna has been designed and developed which is excited by a monopole. The effect of antenna parameters such as layer arrangement is investigated. The proposed antenna has measured bandwidth of 94.44% (S11 ≤ - 10 dB) at 6.8 GHz resonant frequency, which is ranging from 5.7 GHz - 15.9 GHz. The proposed antenna has good radiation pattern, which is very suitable for wideband wireless system applications.

Rotated stacked dielectric resonator antenna with sierpinski fractal for circular polarization

A new economic method for the generation of circular polarization in a dielectric resonator antenna is investigated. The proposed antenna consists of four rectangular dielectric layers, each one is rotated by an angle of 300 relative to its adjacent layers. Utilizing this type of approach produced a circular polarization over a bandwidth of 6.38% ranging from 9.67 to 10.3 GHz. The proposed antenna has impedance bandwidth of 25.32% over the frequency range of X-band(8-12 GHz). The radiation efficiency of the proposed circularly polarized DRA is more than 94.8% with gain more than 5dB in this frequency band of operation.

Design of a new compact UWB polarization diversity antenna with stepped CPW-feed

A new compact UWB polarization diversity antenna with stepped CPW fed is investigated. The antenna comprises two identical monopoles that are printed on a low loss substrate with 7 mm spacing and are placed orthogonal to each other. Results indicate that the proposed antenna has not only ultra wide bandwidth (122.83%for port 1 and 124.95% for port 2), but also good port isolation above 22dBover the entire band of interest. Moreover, radiation patterns demonstrate good orthogonal polarization operation, finally the envelop correlation coefficient has been calculated to evaluate the diversity performance. Results show that ρε ≤ -20 dB across the ultra wide bandwidth. These results identify the suitability of the proposed antenna for future UWB diversity application.

Optimization of skewed omega for left-handed material characteristics

Abstract. Artificial neural network and simulated annealing are applied to obtain optimized design parameters of skewed omega-shaped metamaterial unit cells for providing left-handed material (LHM) with a negative refractive index. The implemented numerical and experimental methods provide evidence for the validity and practicality of the technique. Simulation, with optimized parameters, using CST Microwave Studio, shows that skewed LHMs are low-loss materials.