ﬂuctuation captured was very minimal with an average wave- length ﬂuctuation of 0.008 nm over a period of 60 min. The laser output power also shows a very good stability with an av- erage power ﬂuctuation of 0.0025 dB over a period of 60 min. ACKNOWLEDGMENT This project is sponsored by Ministry of Science, Technology and Innovation (MOSTI) through Science Fund grant scheme, 03-02- 03-SF0016 and Universiti Tenaga Nasional internal research grant scheme, J510050199. REFERENCES 1. T. Ferreira da Silva, D. Thomas, and J.P. von der Weid, Genera- tion of a narrow microwave carrier from a bimodal ﬁber laser, Microwave Opt Technol Lett 54 (2011), 451–454. 2. Q. Wang and Q. Yu, Continuously tunable S and CþL bands ultra wideband erbium-doped ﬁber ring laser, Laser Phys Lett 6 (2009), 607–610. 3. T.A. Haddud, M.H. Al-Mansoori, A.K. Zamzuri, S. Shaharudin, M.K. 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Arrebola 2 1 Universidad Polit ecnica de Madrid, ETSI Telecomunicaci on, Ciudad Universitaria s/n 28040 Madrid, Spain; Corresponding author: ctienda@etc.upm.es 2 Department of Electrical Engineering, Universidad de Oviedo Campus Universitario s/n, E-33203, Gij  on (Asturias), Spain; arrebola@tsc.uniovi.es Received 13 January 2012 ABSTRACT: An offset-fed reﬂectarray demonstrator with reduced cross-polarization has been designed, manufactured, and tested. It is demonstrated that the cross-polarization is signiﬁcantly reduced by using two layers of varying-sized patches and adjusting the patch dimensions not only to shape the beam in dual-linear polarization but also to produce a cancellation of the cross-polarized reﬂected ﬁeld in those zones in which the maximum cross-polarization is produced. The proposed technique provides a reduction better than 5 dB in the cross- polarization for both linear polarizations. The measured radiation patterns are in good agreement with the theoretical predictions, and show a cross-polar discrimination better than 30 dB in the 12.97–14.25 GHz frequency band. V C 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2449–2454, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27106 Key words: antennas; reflectarrays; low cross-polarization 1. INTRODUCTION Reﬂectarray antennas have demonstrated their capabilities to pro- vide high-gain focused beams in large apertures [1] and produce very accurate contoured beams for direct broadcast satellite (DBS) antennas using a ﬂat sandwich with appropriately opti- mized printed patches [2–4]. Contoured beams can be easily gen- erated using reﬂectarrays by implementing an appropriate phase- shift on the reﬂectarray elements and using printed circuit tech- nology and conventional sandwich manufacturing processes [4]. The manufacturing costs are much lower than in conventional shaped reﬂectors due to the elimination of the custom moulds. Reﬂectarrays provide lower cross-polarization than offset reﬂector antennas, mainly because they are ﬂat. Cross-polariza- tion is in the order 30 dB below the maximum for a focused beam reﬂectarray. However, in the case of contoured beams, the absolute level of cross-polarization remains practically the same, but the antenna gain is reduced to fulﬁll the contour Figure 6 Laser output power at different pressure for 150 mW pump power over 60 min DOI 10.1002/mop MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 54, No. 11, November 2012 2449