In this letter, a structural modification technique of simple monopole to improve the input impedance bandwidth by using multiple staircased parasitic rings is suggested. In addition, the shape and size of parasitic rings are optimized to enhance the antenna bandwidth. The final optimized parameter values have been obtained from the parametric studies of the antenna and simple equation evaluating the resonant frequency. The electrical performances of the proposed antenna are verified in terms of the return loss and the radiation pattern by using commercially available softwares, CST MW Studio, and HFSS based on FDTD and FEM algorithms, respectively.

This letter describes a design of an internal quad-band antenna resonating at Cellular (824 894 MHz), DCS/PCS (1710 1880 MHz/1850 1990 MHz), and WiBro (Wireless Broadband Internet, 2300 2390 MHzs) system band by inserting the spiral slits corresponding to the resonant frequencies. In order to accomplish this goal, double-spiral structures are suggested and analyzed by using a commercially available software package based on the finite-difference time-domain (FDTD) algorithm and basic equation for fundamental resonant frequency. In addition to that, the experimental results are compared with the predicted data obtained from the software package, CST MW Studio by considering the criterion of VSWR as 3:1. The proposed antenna and substrate are so small that they can be mounted and packaged in mobile phones. The measured radiation patterns are in good agreement with simulated results.

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This article deals with a design of compact six‐band internal antenna using two identically stacked periodic‐grooved patches and shorting plates and covering the frequency bands composed of cellular (824–894 MHz), GSM (880–960 MHz), DCS (1710–1880 MHz), PCS (1850–1990 MHz), UMTS (1920–2170 MHz), and ISM (2400–2480 MHz) under the criteria −7.3 dB for the first five bands and −6 dB for the last band, respectively. To accomplish this goal, the planar inverted‐F antenna (PIFA) with periodic grooves is suggested, analyzed, and verified by using two commercially available softwares, CST MWS and HFSS based on the FDTD and FEM algorithms, respectively, and carrying out the measurements in terms of return loss, radiation patterns, and gains. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2718–2722, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23776