Design and Performance Analysis of a Low-Profile Spiral Antenna for C-Band Cognitive Radio Applications

This paper presents the design of a low-profile spiral antenna specifically for C-band cognitive radio applications. Spiral antennas, while traditionally recognized for their broad frequency response, can be optimized for narrowband use, maintaining consistent polarization and radiation patterns within a targeted frequency range. The design process, executed using CST Microwave Studio Suite, involves detailed analysis and optimization of the antenna's geometric parameters. Key performance metrics-including return loss, radiation pattern, voltage standing wave ratio (VSWR), gain, and directivity-are systematically evaluated. The proposed spiral antenna achieves a return loss of −25.307 dB, a VSWR of 1.1148, a gain of 5.38 dBi, and a directivity of 6.621 dBi, centered at a narrow bandwidth of 6.864 GHz. These results highlight the antenna's suitability for effective long-range communication in fixed satellite service applications, emphasizing its role in enhancing spectrum utilization in cognitive radio networks.