Broadband Circularly Polarized Antenna Array with Sequential Rotation Feeding and a Windmill-Shaped Defected Ground...

Area of Science:

• Electrical Engineering
• Antenna Theory and Design
• Wireless Communications

Background:

• Wireless Local Area Network (WLAN) systems require antennas with high gain, wide bandwidth, and stable circularly polarized (CP) radiation.
• Existing antenna solutions may not fully meet these demanding requirements for modern wireless applications.

Purpose of the Study:

• To propose and implement a broadband circularly polarized array antenna for the 2.4-2.484 GHz ISM band.
• To enhance antenna performance in terms of gain, bandwidth, and polarization stability for WLAN applications.

Main Methods:

• Design of a coplanar waveguide fed broadband CP monopole antenna as the radiating element.
• Utilization of a sequential rotation technique to create a four-element array.
• Introduction of a windmill-shaped defected ground structure to extend bandwidth.

Main Results:

• Achieved -10 dB impedance bandwidth of 1.22-2.78 GHz (87.1% relative bandwidth).
• Obtained 3-dB axial ratio bandwidth of 1.85-2.66 GHz (35.0% relative bandwidth).
• Measured peak gain of 8.2 dBic with left-hand circular polarization at 2.45 GHz and cross-polarization discrimination better than 20 dB.

Conclusions:

• The proposed array antenna demonstrates a robust solution for WLAN access points and Internet of Things gateways.
• The antenna exhibits wide bandwidth, high gain, and strong anti-interference capabilities, outperforming traditional linear-polarized antennas in multipath environments.