The notch disappeared, but the transfer function is not totally flat, like in the simulations. The reason of this difference between simulations and measurements is caused by the imper- fections of the OSSB filter. After the experiments of the OSSB modulation, the effect of the mode filter is measured as well. The SMF patchcord theoret- ically filters off every mode groups except one. The simulations show that, the mode filter is very effective, so it should be tested by experiments as well. The transfer function of 1 km MMF is measured, and the impact of SMF patchcord is investi- gated. The results of these measurements are shown in Figure 7. As it can be seen, the transfer function of the 1 km MMF has a local minimum at 1 GHz and around 3 GHz. The SMF patchcord is capable to reduce the ripple of the transfer function, and it can emphasize the local minimums, and it makes the characteristics flat. This result shows that, SMF patchcord can improve the transfer function, and it can compensate the modal dispersion effects. According to these measurements, the pur- posed compensator is efficient and it can reduce the effect of the modal dispersion and the chromatic dispersion respectively in mm-wave over fiber systems. 5. CONCLUSION A dispersion compensator is purposed in this article, which applies an SMF patchcord as a mode filter, and a BPF as an OSSB filter. The OSSB filter is placed at the receiver, so this filter can work as an OSSB filter and a mode filter together. To prove its efficiency simulations and measurements are made, which show that the pur- posed compensator works efficiently. Both transfer function and EVM simulations show strong improvement in the connection. The compensator reduces the EVM to 15% at notch point of the transfer function. The experiments demonstrate that the purposed compen- sator can compensate both chromatic dispersion and modal disper- sion. 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PLANAR SQUARE MULTIBAND FREQUENCY RECONFIGURABLE MICROSTRIP FED ANTENNA WITH QUADRATIC KOCH-ISLAND FRACTAL SLOT FOR WIRELESS DEVICES Imen Ben Trad, 1 Hatem Rmili, 2 Jean Marie Floch, 1 Wassim Zouch, 2 and Mohamed Drissi 1 1 IETR, INSA, 20 Avenue Buttes des Co€ esmes 35043, Rennes, France 2 Electrical and Computer Engineering Department, King Abdulaziz University, Faculty of Engineering, P.O. Box 80204, Jeddah 21589, Saudi Arabia; Corresponding author: hmrmili@kau.edu.sa Received 27 May 2014 ABSTRACT: A planarprinted multiband microstrip fed antenna with reconfigurable frequency performance was designed for multistandard wireless communication systems. The antenna consists on a square shaped patch with an optimized centered Koch-Island fractal slot. The antenna allows a reconfigurability of the frequency bands by incorporat- ing 16 PIN diodes inside the fractal slot which is highly complex. That is why short and open circuits will be used to produce frequency agility instead of RF switches (for proof of the concept). The proposed antenna is capable to switch between 15 operating frequency bands centered at 1.7, 1.77, 2.36, 2.43, 3.30, 3.61, 3.67, 3.79, 4.05, 4.34, 4.59, 5.2, 5.27, 5.47, and 5.57 GHz through four operating modes M1–M4 over the wide range 1–6 GHz. Prototypes corresponding to different modes were manufactured and characterized. Simulated and measured results are presented and discussed. V C 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:207–212, 2015; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.28815 Key words: fractal slot; multiband antenna; frequency reconfigurable antenna; PIN diode DOI 10.1002/mop MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 57, No. 1, January 2015 207