Design and modeling of quasi-lumped planar inverted-f antenna for handheld devices
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Date
2016-02-01
Authors
Majid Rafiee
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Abstract
Nowadays, increasing demand for having high bit rate in wireless mobility has enabled the introducing Fourth Generation (4G) and beyond technologies. Realizing this fact, conformable, unobtrusive, lightweight, low cost, and ubiquitous equipment, which can be integrated into small terminals such as mobile handsets, are now crucial design con siderations. Recently, Planar Inverted-F Antenna (PIFA) is widely used as the main antenna in these small terminals due to its small electrical length and good SAR. How ever, having a 3D structure is the main challenge for antenna designers to fabricate
and use it as a small, compact integrated antenna. Although, in current phones, the main PCB is used as a ground plane, implementing many other electronic devices on the ground plane effect on the antenna performance. In addition, this height,makes the phone thicker. This forces antenna designers to find another ground plane such as phone body (none-ideal). However, this kind of ground plane also suffers by users’ hand. Therefore, the intent of this work is to develop an alternative antenna structure that meets the compact requirements in terms of size, without compromising the PIFA characteristics. Another challenge with the conventional PIFAs is its feeding struc ture. Therefore, a unique Two Dimensional (2D) antenna design configurations with single and dual CPW-fed quasi-lumped quasi-PIFA antenna is proposed in this work. The design is a simple, single CPW-fed quasi-lumped quasi-PIFA antenna arrange ment which was excited by the simplest feeding structure i.e. a microstrip line. The viantenna structure was photo-edged on a Duroid RO4003C with a permittivity of 3.38 and thickness of 0.813 mm. The size of the resonator is 15 × 11mm2 with conductor thickness of 0.035 mm. The design and radiation equations were presented followed by the modeled, simulated, fabricated, and measured results to determine its performance
characteristics thereby accrediting the inherent potential of the proposed structure as an antenna. The antenna was optimized to operate in 2.6 GHz, with a good agreement be tween the simulation results and experimental data over measured 13.65% impedance bandwidth. The antenna demonstrated an omnidirectional radiation pattern in the H plane and a dipole like pattern in E-plane at desired frequency. A dual elements MIMO
antenna was designed, modeled, simulated, fabricated and measured based on the per formance of the first configuration. ADS was used for modeling and CST and HFSS were used to simulate the design. The measured bandwidth of 10.73% for first element and 12.19% for the second element were obtained. Also, the simulated result for SAR were in agreement with European Union (EU) and United State (US) standards. Also, Matlab and Mathematica were used for plotting in order to an exact parameter study
on proposed structure. Findings indicate that all the experimental results are in good agreement with the modeled and simulated results. The proposed antenna has superior advantages of improved measured bandwidths, easy to fabricate, low cost and most importantly significant small size advantage which ensures its required compactness by having 2D structure while maintaining the advantage of PIFA i.e. having low SAR. Besides the aforementioned advantages, the proposed antenna has significant small
size advantage which ensures its required compactness.