Compact high-gain circularly polarized patch antenna based on TM30/TM03 mode

Area of Science:

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

Background:

• Microstrip patch antennas are widely used due to their low profile and conformability.
• Achieving high gain and circular polarization simultaneously in a compact form factor remains a challenge.
• Reducing back radiation is crucial for many antenna applications to minimize interference.

Purpose of the Study:

• To design and validate a circularly polarized (CP) microstrip patch antenna with high gain and compact dimensions.
• To investigate the use of high-order modes for enhanced radiation performance.
• To reduce back radiation using a substrate integrated waveguide (SIW) cavity.

Main Methods:

• Employed a high-order mode patch antenna design.
• Utilized diagonal feed and unequal center crossed slot to generate orthogonal TM03 and TM30 modes.
• Integrated a substrate integrated waveguide (SIW) cavity around the patch to reduce back radiation.
• Fabricated and measured an antenna prototype for validation.

Main Results:

• The proposed antenna achieved a compact size of 1.27λ x 1.27λ x 0.03λ at the center frequency.
• Measured operating bandwidth (S11 < -10 dB, AR < 3 dB) from 5.435 to 5.475 GHz.
• Achieved high gain radiation of approximately 12 dBi within the operating band.
• Reduced back radiation by two times compared to a similar antenna without the SIW cavity.

Conclusions:

• The developed high-order mode microstrip patch antenna effectively radiates high-gain CP waves.
• The integration of an SIW cavity is a viable method for achieving compact size and reducing back radiation.
• The prototype measurements validate the design's performance, demonstrating its suitability for applications requiring high gain and low back lobes.