Figure 5 shows the percentage error in calculated quality factor versus r max . For better illustration of the effect of the conductivity, this figure is plotted in a logarithmic scale. It is clear that for r max between 3310 4 and 1:5310 5 , the error is <1%. As depicted, same as the case of Figure 4, there is an optimal range of r max for a known AB width and k max . For ensuring the accuracy of the method and increasing the optimal range of the parameters, one can increase the AB width. Moreover, performance of the method can be tested by plotting the field distribution. CONCLUSIONBy introducing a radial AB medium and applying the onedimension finite-elements method, a precise method for the calculation of the quality factors and resonance wavelength of the WGM microresonators is proposed. The capability of the proposed method was proved by comparing the results with those obtained by full wave method. Electron 12 (2006), 15-32. 2. M. Mohammad-Taheri and D. Mirshekar-Syahkal, Accurate determination of modes in dielectric loaded cylindrical cavities using a onedimensional finite element method, IEEE Trans Microwave Theory Tech 37 (1989), 1536-1540. 3. E. Bagheri-Korani, M. Mohammad-Taheri, and M. Shahabadi, One dimension finite-elements method for the analysis of Whispering Gallery microresonators, J Opt Soc Am A 31, 1614-1622. 4. K. Sankaran, C. Fumeaux, and R. Vahledieck, Uniaxial and radial anisotropy models for finite-volume Maxwellian absorber, IEEE ABSTRACT: The present study demonstrates the designing and characterization of a circular patch antenna having an impedance bandwidth of 2.4-13.8 GHz with band notch at WLAN operating region. The small size (30 3 40 mm 2 ) and large bandwidth (140.7% fractional band width) makes it suitable for different UWB applications. Different size reduction and matching techniques are used in this model to achieve a better response. The Quarter wave transformer matching technique is used for broad band impedance matching between the radiating circular patch and the 50 ohm source impedance. The simple design and good agreement between the simulation and the experimental results makes the design a suitable candidate for practical applications.

This literature demonstrates the study of design and parametric characterization of a tree shaped microstrip patch antenna with dual band notch characteristic for Ultra wideband (UWB) applications. This proposed design is characterized by an enhanced impedance bandwidth of 2.2–19.5 GHz (159% Percentage bandwidth) with dual band notch characteristic at Wi‐MAX band (3.3–3.7 GHz) and upper WLAN band (5.15–5.85 GHZ). The wide impedance bandwidth is achieved by using a special tree shaped radiator with modified front and back ground plane. The band rejection in wireless local area network (WLAN) band is achieved by etching a Rectangular Split Ring Resonator (RSRR) structure in the radiator part and for Wi‐MAX, a Spiral shaped Defected Microstrip Structure (SDMS) in the feed mechanism. The overall dimensions of the proposed antenna are 28 × 35 × 1.6 mm3. The antenna is characterized by high gain (about 7.5 dB max) in the entire operating frequency band except the notched frequency bands. The simulated and the experimental results are in good agreement. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1658–1661, 2016

The design of a compact modified octahedron shaped dual band notched ultra wide-band antenna is presented in this article. The impedance bandwidth of the designed antenna has been enhanced by modifying the shape of the radiator by introducing fractal geometry and a modified ground plane. The proposed antenna offered an impedance bandwidth of 2.4 GHz-19.5 GHz (156% Fractional bandwidth). Two rectangular split ring resonator structures are introduced in the radiator to achieve two notched bands which ranges from 3.3 GHz to 3.7 GHz (WiMAX) and 5.15 GHz-5.85 GHz (WLAN) band. The antenna gain varies from 1 to 4 dBi over the operating band except the notched bands. The overall dimension of the designed antenna has a compact size of 33 3 40 mm

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This present study deals with the designing aspects of a planar hexagonal patch ultra wideband antenna on metamaterial substrate operating in the millimetre frequency band using fractal structure. The presented design is having a bandwidth of around 13 GHz (22.7 GHz -35.7 GHz). The CPW feeding system enables the design for a proper matching and signal distribution. The use of fractal structure enabled the intended current distribution around the edges of the proposed antenna structure with widened bandwidth.