Broadband polarization-adjustable antenna realized by waveguide circular polarizers

Area of Science:

• Electromagnetics and Wave Propagation
• Antenna Theory and Design
• Microwave Engineering

Background:

• Traditional antennas often have fixed polarization, limiting their adaptability in diverse communication scenarios.
• Achieving broadband operation with multiple polarization modes typically requires complex antenna structures.

Purpose of the Study:

• To propose and validate a broadband antenna capable of adjusting its polarization state.
• To demonstrate switching between horizontal, vertical, left-hand circular, and right-hand circular polarization modes.
• To assess the antenna's performance for potential high power microwave applications.

Main Methods:

• Design of a broadband antenna incorporating a rectangular-to-circular transition waveguide, two rectangular slot circular polarizers, and a conical horn.
• Analysis of the polarization adjustment principle through polarizer rotation.
• Simulation, optimization, fabrication, and measurement of an X-band prototype.

Main Results:

• The antenna achieved a reflection coefficient below -18 dB across all polarization modes from 9.2 to 10 GHz.
• Linear polarized modes exhibited gains exceeding 10.5 dBi.
• Circular polarized modes showed comparable gains with an axial ratio under 1 dB within the operating band.

Conclusions:

• The fabricated antenna successfully demonstrated broadband operation with adjustable polarization.
• Measured results validated the simulation, confirming excellent polarization adjustment performance.
• The proposed antenna design shows significant potential for high power microwave systems.