Dual-Port RHCP Compact Antenna at 868 MHz Using a 120° Hybrid Coupler

This work presents the design of a compact dual-port circularly polarized antenna based on the new coupler topology. The antenna can radiate a right-hand circular polarization (RHCP) in two opposite directions depending on the input port. In the proposed structure, the radiating system has three inverted F antennas connected to a 120° hybrid coupler. The modeling and design of the 5-ports hybrid coupler are described and experimentally validated. The antenna prototype is fabricated using two 1.6mm-thick low-cost FR4 Epoxy substrates assembled with metal wires, with a dimension of 80mm
$\times80$
mm
$\times12$
mm (ka
$ < 0.74$
). The proposed antenna provides the realized RHCP gain of 2.4 dBic and 1.8dBic at 868 MHz for Port 1 and Port 2, respectively.