A Substrate‐Integrated Suspended Line‐Based Circular Patch Antenna With Single‐/Dual‐Band Switching and Frequency Tuning Capability

ABSTRACT This letter presents a novel frequency‐reconfigurable aperture‐coupled circular patch antenna based on substrate‐integrated suspended line (SISL) technology, designed for single‐/dual‐band switching and frequency tuning in the C‐band. The proposed antenna consists of an aperture‐coupled circular patch with a sectoral slot and a biasing circuit to control a single PIN diode or a pair of varactor diodes. The characteristic mode analysis (CMA) was instrumental in the design of the reconfigurable patch and the feeding. The first antenna configuration can switch between single and dual‐band operation, with a single band operating at 5.6 GHz with 11.62% fractional bandwidth (FBW) and a peak realized gain of 9.01 dBi, and a dual‐band at 5.3/6 GHz with 6.04%/6.17% FBW and 8.57 dBi peak realized gain. The second antenna configuration (with the same physical structure) can tune the operational frequency between 4.84 and 5.89 GHz based on varactor diode reverse bias voltage with a frequency ratio (FR) of 1.22 and achieve a peak realized gain of 9.44 dBi within the tuning range. Both antenna configurations exhibited stable broadside radiation. The total antenna size is , where is the free space wavelength corresponding to the lowest operating frequency. This study provides a comprehensive solution for next‐generation wireless systems by combining a compact platform, innovative feeding mechanisms, and state‐of‐the‐art analysis techniques.