A Broadband Circularly Polarized Reflectarray With Magneto-Electric Dipole Elements

This communication reports a broadband circularly polarized (CP) reflectarray operating at
$X$
-band. An asymmetric dual-polarized magneto-electric (ME) dipole is proposed as the reflectarray element to realize broadband cophasal far-field radiation based on the element rotation technique. Broad bandwidth and high-purity circular polarization are achieved. The fabricated prototype shows a 1.5 dB axial ratio (AR) and 3 dB AR bandwidth of 37% and 42%, respectively. Peak gain of 25.4 dBic and peak aperture efficiency of 60% are experimentally obtained. The aperture efficiency remains higher than 45% over a wide bandwidth spanning from 8.3 to 12.4 GHz. Specifically, the proposed element can be realized on an air gap-free low-profile single-board substrate configuration, owing to the wideband characteristic of the ME dipole. This comparatively robust and easy-to-fabricate structure would be desirable for many applications including broadband satellite communications.