Performance analysis of multiband frequency-reconfigurable antenna for cognitive radio applications

This work presents a multiband, frequency-reconfigurable antenna developed for cognitive radio systems. Cognitive radio is an advanced wireless communication framework capable of autonomously sensing vacant spectrum bands and reconfiguring its transmission parameters to enhance spectral efficiency and mitigate interference. The proposed antenna is implemented using a rectangular microstrip patch structure with Rogers RT5880 substrate material with overall dimensions of 45 × 45 × 1.5 mm 3 . Reconfigurability is facilitated by three PIN diodes integrated between the radiating sections, enabling discrete switching among multiple frequency modes. The antenna successfully covers several operational bands, including 1.9 GHz (4G LTE), 2.45 GHz (Wi-Fi), 5.4 GHz (WLAN), and 5.9 GHz for dedicated short-range communication (DSRC). Across all bands, the voltage standing wave ratio (VSWR) remains below 1.5, indicating excellent impedance matching. The design achieves an efficiency of 89% and a maximum gain of 3.5 dBi. A prototype of the antenna was fabricated and experimentally characterized, and the measured results exhibit close agreement with the simulation data, thereby confirming the reliability and practical viability of the proposed design.