This paper presents a tunable balanced antenna covering WLAN frequency bands near 2.4 GHz (2.4–2.4835 GHz) and 5 GHz (5.15–5.35 GHz & 5.650–5.925 GHz), for mobile application. The design is based on loading two variable capacitors onto the planar balanced antenna to electronically tune its resonant frequency; the higher frequency was tuned with the capacitance varying from 0.1pf to 0.3pf, while the lower frequency band remains constant. Performance of the proposed antenna was analyzed and optimized against the two targeted frequency bands. For validation, the antenna prototype was fabricated and tested then the measured results were compared to simulation ones. The performance of this proposed antenna was verified and characterized in terms of the antenna reflection coefficient |S11|, radiation pattern and power gain.
[Show abstract][Hide abstract] ABSTRACT: A new technique for designing dual-band reconfigurable slot antennas is introduced. The technique is based on loading a slot antenna with a lumped capacitor (or varactor) at a certain location along the slot. Given a fixed capacitor location along the slot, decreasing the capacitance results in increasing the first and second resonant frequencies of the slot antenna. However, the changes in the resonant frequencies are significantly different for the first and second resonances and, hence, a dual-band antenna with considerable frequency ratio tuning range can be obtained. Based on this technique, an electronically tunable dual-band antenna with a frequency ratio in the range of 1.2-1.65 is designed and fabricated using a single varactor with a capacitance range of 0.5-2.2 pF. The antenna has similar radiation patterns with low cross-polarization levels at both bands and across the entire tunable frequency range.
IEEE Transactions on Antennas and Propagation 03/2006; 54(2-54):401 - 408. DOI:10.1109/TAP.2005.863373 · 2.18 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: As commercial needs have expanded the functions of the wireless cellular handsets, multiantenna development in one handset has become more and more common. This paper addresses a multiantenna solution for the wireless handset application. A planar inverted "F" antenna (PIFA) was designed as the main antenna of the handset to cover the 800 MHz band (824 MHz-894 MHz) and the 1900 MHz band (1850 MHz-1990 MHz). A side-mounted inverted "F" antenna (IFA) was designed as the 1575.42 MHz global positioning system (GPS) antenna. The location of the feed/ground pins of both antennas affected not only the total antenna efficiency, but also the polarization of the GPS IFA. The length of the GPS IFA affected the isolation between the two antennas and the specific absorption rate (SAR) of the PIFA at the 1900 MHz band. A three-dimensional efficiency measurement of the prototypes in both free space and against-head position will be presented. Measurement of SAR and its distribution will also be presented to demonstrate the impact of the IFA on the near field of the PIFA.
IEEE Transactions on Antennas and Propagation 06/2005; 53(5-53):1770 - 1778. DOI:10.1109/TAP.2005.846807 · 2.18 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: There are two novel printed inverted-F antenna (PIFA) related dual-band antennas for 2.45 and 5.25 GHz wireless local area network (WLAN) applications introduced in this paper. One is designed by spiraling the tail of the PIFA and the other is by modifying the feed structure of the PIFA into a coupling configuration. An equivalent transmission line model is proposed to explain the dual-band operation of the spiraling PIFA. The measurement results show that the former antenna has a 10 dB return loss with bandwidth 140 MHz in the 2.45 GHz frequency band and bandwidth 756 MHz at 5.25 GHz, whereas the latter one has the bandwidth 240 MHz at 2.45 GHz and bandwidth 672 MHz at 5.25 GHz. In addition, omnidirectional radiation patterns are achieved at those operating frequency bands with average antenna gains near 0 dBi. The proposed antenna possesses the properties of good performance, compact size (about 50% of a typical PIFA), low profile, and low cost; hence, it is suitable for practical applications in a combo WLAN system
IEEE Transactions on Antennas and Propagation 04/2007; 55(3-55):805 - 811. DOI:10.1109/TAP.2007.891843 · 2.18 Impact Factor
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