A new miniaturized folded fractal based PIFA antenna design for MIMO wireless applications

Design of a new miniaturized FF-PIFA (Folded Fractal Planar Inverted F-antenna) with dual-band resonant behavior is introduced in this paper for use in the dual-band WLAN MIMO (multi-input multi-output) applications. Firstly, the fourth iteration Koch's fractal geometry has been applied to the edges of the conventional rectangular patch structure to create a single miniaturized antenna. Then for further miniaturization, the radiating patch is folded in its sides. A substrate with relative permittivity of 2.2 and thickness of 0.9 mm has been used. The proposed antenna is located at the corner of a copper ground plane of 0.05mm thickness and dimensions of 110 × 70 mm2. The dimensions of the single antenna are 12mm × 15mm × 6.2 mm, making it suitable for mobile terminal applications. The proposed antenna offers a dual-band resonance covering the two WLAN band standards. Modeling and performance evaluation of the proposed antenna have been carried out using the CST Microwave Studio. After that, the FF-PIFA antenna has been investigated in a 4 by 4 MIMO system suggested for use in dual band WLAN applications. Simulation results show that the MIMO system offers ≤ -10 dB impedance bandwidths of about 182.32MHz with an isolation more than 12.17 dB, for the lower band, and 400MHz with an isolation of higher than 20 dB, for the upper band. This makes the proposed system suitable for use in MIMO dual-band WLAN applications.