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A novel frequency and pattern reconfigurable Yagi antenna is proposed. The antenna is formed by a driver, a reflector and two directors. The introduction of switches using a PIN diode at the arms of the driver element produces three switchable frequencies at 1.25 GHz, 1.85 GHz and 2.45 GHz. By controlling the switches at the directors and reflector, the radiation pattern can be configured to near omni-directional pattern or directional pattern at those three frequencies. Simulated and measured results are used to demonstrate the performance of the antenna. The simulated and measured return losses and the radiation patterns, are presented and compared. It was found that the gain of the antenna increases from 3.3 dB to 5 dB in a directional pattern, when compared to the near omni-directional pattern. [ABSTRACT FROM AUTHOR]

In this article, the design of log periodic fractal Koch antenna using the second iteration has been developed for ultra high frequency band applications. The ability to reduce the size as maintaining the performances of the antenna such as input return loss and radiation patterns brings fractal Koch and becomes enticing among researchers. The design of the log periodic fractal Koch antenna has been elaborated in this article. The computer simulation technology software has been used to analyze the performances of the designed antenna. This has been compared between simulation and measurement. The results show that this antenna has been reduced by up to 27% in size from the normal log periodic planar dipole antenna. The performance of the antenna has been compared in terms of return losses, bandwidths, and radiation patterns. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26111 [ABSTRACT FROM AUTHOR]

ABSTRACT A wideband antenna fed by a coplanar waveguide (CPW) with reconfigurable function is presented. The wideband function is achieved from 1.39 GHz to 8.11 GHz using an elliptical radiator with a CPW feed line. Meanwhile, three pairs of slot dipoles which are fed by CPW are used to achieve triple-band function at 2.4 GHz, 3.5 GHz and 5.2 GHz. Four ideal switches are placed on the proposed antenna. The proposed antenna is designed, simulated, fabricated and tested. All simulated and measured results of return loss, radiation pattern and gain are presented. Good results of return loss and radiation pattern are obtained thus verifying that the proposed antenna is suitable for future multimode radio systems. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:2079-2082, 2016 [ABSTRACT FROM AUTHOR]