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.
In this letter, an innovative technique is proposed to enhance the port-to-port isolation of two closely spaced dual-band radiating elements in the WLAN 2.4-2.5-GHz and 5.15-5.825-GHz frequency bands. This broadband technique consists in inserting an optimized parasitic element between the two antennas of a multiple-input-multiple-output (MIMO) set-top box. High port-to-port isolation is obtained, and the computation of the diversity performance shows suitability for enhanced diversity and MIMO applications.Index Terms-Diversity and multiple-input-multiple-output (MIMO) techniques, dual-band, isolation, multiantenna systems, parasitic element, WLAN.
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