This letter presents a dual-band circularly polarized patch antenna dedicated to satellite communications. The dual-band behavior is obtained by inserting a small X-band microstrip patch antenna into a large L-band one. Both patches are printed on the same substrate and fed by electromagnetic coupling through two perpendicular slots etched in their ground planes. These slots are fed by two different 90 microstrip branch-line couplers printed on a stacked lower substrate. A prototype of the antenna was realized with a 1.5-mm-thick upper layer substrate and a 0.758-mm-thick feed layer substrate, both of the same dielectric material with a relative permittivity of r = 2 22. Simulation and measurement results are presented, showing this compact dual-band antenna achieves the required Meteosat specifications in terms of frequency bandwidth, circular polarization bandwidth, and isolation between the two communication bands.Index Terms-Circular polarization, dual-band antennas, hybrid branch-line couplers, microstrip patch antennas, satellite communications.

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International audienc

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This paper presents the design methodology, simulation and measurement results of a CMOS 12GHz Rotary Travelling Wave Voltage Controlled Oscillator. The different simulations (electrical using SPICE and electromagnetical using HFSS) are presented. These results are compared to a theoretical approach and measurements. The oscillator has been fabricated in a 0.13µm RF-CMOS technology. The phase noise at a 1MHz offset from the carrier is105dBc/Hz and the tuning range is 1.2GHz for a global consumption of 25mA.